Aerosol Envelope Sealing 

of New Residences

December 2020
NOTICE

This work was prepared as an account of work sponsored by an agency of 

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ii
iii

Aerosol Envelope Sealing 

of New Residences

Prepared for:

U.S. Department of Energy Building America Program

Office of Energy Efficiency and Renewable Energy

Prepared by:

Dave Bohac

Center for Energy and Environment

212 3rd Avenue North, Suite 560

Minneapolis, MN 55401

Curtis Harrington

UC Davis Western Cooling Efficiency Center

215 Sage St., Suite 100

Davis, CA 95616

December 2020

Suggested Citation

Bohac, Dave, and Curtis Harrington. 2020. Aerosol Envelope Sealing of New 

Residences. Minneapolis, MN. DOE/GO-102020-5475. www.nrel.gov/docs/

fy21osti/78112.
iv

This material is based upon work supported by the 

Department of Energy’s Office of Energy Efficiency and 

Renewable Energy (EERE) under the Building Technologies 

Office under Award Number EE0007573.

The work presented in this EERE Building America report 

does not represent performance of any product relative to 

regulated minimum efficiency requirements. 

The laboratory and/or field sites used for this work are not 

certified rating test facilities. The conditions and methods 

under which products were characterized for this work differ 

from standard rating conditions, as described. 

Because the methods and conditions differ, the reported 

results are not comparable to rated product performance 

and should only be used to estimate performance under 

the measured conditions.
In cooperation with the Building America Program, 

the Center for Energy and Environment team is 

one of many Building America teams working 

to drive innovations that address the challenges 

identified in the program’s Research-toMarket Plan.

This report, Aerosol Envelope Sealing of New 

Residences, explores the process for integrating 

aerosol envelope sealing in new homes, and 

evaluates sealing performance relative to 

conventional sealing methods. A total of eight 

builders in Minnesota and California participated 

in the research, providing homes for testing and 

feedback on appropriate stages of construction 

to apply the sealing.

As the technical monitor of the Building America 

research, the National Renewable Energy 

Laboratory encourages feedback and dialogue 

on the research findings in this report as well as 

others. Send any comments and questions to 

building.america@ee.doe.gov.

v

FOREWORD

The U.S. Department of Energy (DOE) 

Building America Program has been 

a source of innovations in residential 

building energy performance, durability, 

quality, affordability, and comfort for 

more than 20 years. This world-class 

research program partners with industry 

to bring cutting-edge innovations and 

resources to market.
ACKNOWLEDGMENTS

The work presented in this report was funded by the U.S. Department of Energy (DOE), 

Office of Energy Efficiency and Renewable Energy, Building Technologies Office. 

Photo Credits

Cover, from top to bottom: Photos from iStock 182149008, 178447161, 184944590, 467972591;

Page ii and iii: Photo from iStock 182149008;

Page v: Photo by Dennis Schroeder, NREL 28764;

Page vi: Photo from iStock 183245764;

Page vii: Photo from iStock 496703961;

Page viii: Photo from iStock 148484827;

Page ix and xi: Figures from Center for Energy and Environment;

Page x, xii, xiii, xiv: Photos from Center for Energy and Environment

vi
ACH50 leakage flow rate in air changes per hour at an induced pressure 

of 50 pascals

CFM50 leakage flow rate in cubic feet per minute at an induced 

pressure of 50 pascals

cfm cubic feet per minute

DOE U.S. Department of Energy

HERS Home Energy Rating System

HVAC heating, ventilating, and air conditioning

ICC International Code Council

IECC International Energy Conservation Code

WCEC Western Cooling Efficiency Center at UC Davis

LIST OF ACRONYMS

vii
apply the sealing. The cost of the aerosol 

sealing and resulting house tightness were 

compared to a similar group of houses that 

used conventional sealing methods. Aerosol 

sealing produced tighter houses overall. 

Researchers also evaluated conventional 

sealing methods to determine whether they 

can be eliminated or reduced to improve 

cost-effectiveness.

Methodology

The project team used a stepwise, iterative 

approach to develop and refine aerosol 

envelope sealing guidelines. This approach 

allowed experience from sealing each 

builder’s initial set of houses to inform 

and refine sealing methods for their second 

set of houses, as shown in Figure 1.

Visual inspections of the homes showed 

an overall high quality of sealing work. 

Several locations were identified as 

being appropriate to seal with the aerosol 

approach. Although aerosol sealing can seal 

leaks that have a width of up to 0.5 in., the 

method is most effective and efficient at 

sealing narrower, distributed leaks of 0.25 

in. or less. With aerosol sealing, hundreds 

of linear feet of these narrow leaks can all be 

sealed simultaneously, reducing the amount 

of time needed for manual inspection 

and sealing.

Results

Aerosol sealing was performed on 11 homes 

in California and 15 homes in Minnesota. 

The sealing was very effective at sealing 

air leaks in the homes. Many of the 

The project team worked directly with 

builders to identify the best stages for 

incorporating aerosol sealing from 

the perspectives of cost, performance, 

and seamless integration into the 

construction process. A total of eight 

builders in Minnesota and California 

participated in the research, providing 

homes for testing and feedback on 

appropriate stages of construction to 

EXECUTIVE 

SUMMARY

This project investigated the use of an 

aerosol-based sealing method to reduce 

air leakage of new homes in the United 

States. The process involves pressurizing 

the building while dispersing an aerosol 

sealant “fog” to the building interior. As 

air escapes the building through leaks 

in the envelope, the sealant particles are 

carried to the leaks where they make 

contact and stick, sealing the leaks. A 

standard blower door and connected 

laptop are used to facilitate the sealing 

process and to provide real-time feedback 

and a permanent record of the sealing. 

The technology is thus capable of 

simultaneously measuring, locating, and 

sealing leaks in a building automatically. 

viii
demonstrations resulted in a tightness below 1.0 ACH50, which is well 

below the California Energy Code target of 5.0 ACH50 and Minnesota 

Energy Code requirement of 3.0 ACH50. Furthermore, the low air leakage 

was often achieved at an early stage of construction before much of the 

manual sealing was performed. This project demonstrated the ability to 

seal homes at various stages of construction, including before or after 

drywall is installed.

California Homes

In California, the aerosol sealing demonstrations were split into two 

categories: homes with unvented attics and homes with vented attics. 

The unvented attic demonstrations looked at the performance of aerosol 

sealing when applied in conjunction with both open-cell spray foam 

insulation at the roof deck as well as with cellulose insulation at the roof 

deck. In both cases, the homes were sealed before wall insulation and 

drywall was installed and after all of the exterior penetrations were made. 

Results showed that the aerosol sealing did a better job of air sealing the 

homes, allowing the builder to choose lower-cost insulation products. 

The combination of open-cell spray foam and aerosol sealing resulted in 

tighter homes overall compared to homes insulated with cellulose. The 

homes with spray foam achieved leakage rates of 1.1 ACH50 compared 

to 2.6 ACH50 for the homes with cellulose; however, challenges with 

integrating the aerosol sealing process due to the cellulose-insulated 

homes’ design differences contributed to the higher leakage rates. The 

control homes that were not sealed with aerosols showed higher leakage 

rates for the homes using cellulose, with an average leakage of 5.1 ACH50

compared to 1.8 ACH50 for the homes with open-cell foam. 

ix

Figure 1. Iterative approach to evaluating aerosol sealing options
The vented attic demonstrations in California were performed after drywall 

was installed and taped, because that is when the air barrier is in place. 

The aerosol sealing process was very effective at this stage of construction, 

sealing more than 70% of the envelope 

air leakage. The homes sealed with 

aerosols were 33% tighter (3.1 ACH50) 

than the control homes (4.6 ACH50). 

There were significant increases in 

the measured leakage from the test 

conducted after the aerosol sealing 

was complete to the test at the end of 

construction. The vented attic homes 

showed significant increases in leakage 

after the aerosol sealing installation. 

Several leak sites were taped over and 

unsealed by aerosol sealing material, 

including fire sprinklers and exhaust 

ventilation systems. Fire sprinklers are 

required in homes built in California, 

and air leakage measurements were 

taken on a small sample of sprinklers in 

the homes, showing an average air leakage of around 10 cfm50 each. These 

sprinklers had to be taped over during the aerosol sealing installation to 

prevent damage and maintain functionality of the equipment. Considering 

that homes can have more than 10 sprinklers, this results in 100 cfm50 of 

leakage to the attic that cannot be sealed. For homes with unvented attics, 

the air barrier is at the roof deck, above the sprinklers, so the air leakage of 

sprinklers to the attic does not affect the overall leakage rate. Leakage was 

found through the backdraft dampers in the exhaust systems, with 200–300 

cfm50 of leakage. These leaks accounted for a significant fraction of the 

increase in leakage measured and cannot be sealed by design; rather, betterdesigned ventilation and sprinkler systems are needed to accommodate 

tighter homes.

Minnesota Homes

The homes sealed in Minnesota all had vented attics, but a strategy was 

developed for aerosol sealing the homes before insulation and drywall. 

x
The builder’s standard practice is to install reinforced polyethylene 

(poly) sheets on the second-floor ceiling to complete the house’s air 

barrier and allow pressurization for the aerosol sealing to be performed. 

The poly installation was at a slightly different stage of construction 

than occurs normally, and for some houses required an additional visit 

to the house by the insulation contractor. Prior to the aerosol sealing, 

spray foam was applied at the rim joists and can foam was used to seal 

around windows and attic 

penetrations. The California 

builders do not install poly 

sheets on the interior, so this 

was not an option for the vented 

attic homes without incurring 

additional costs. Additionally, 

some sealing demonstrations in 

Minnesota residences occurred 

after drywall toward the end 

of construction.

The first builder was a large, national builder with multiple developments 

in the Minneapolis-St. Paul metropolitan area. Seven houses were sealed, 

all before drywall was installed and after reinforced poly was installed 

at the second-floor ceiling. This builder had already been achieving 

high levels of air sealing, with the initial assessment showing leakage of 

1.2–1.5 ACH50, so the goal was to find opportunities to reduce the costs 

of conventional sealing work. Several features or products were identified 

as possible to eliminate from the conventional sealing process. Two of 

the homes had wall insulation installed prior to the aerosol installation, 

which significantly reduced the effectiveness of the sealing process 

and increased the injection time. For the houses without wall insulation 

present, the aerosol sealing reduced leakage by 80%, and the houses 

ended up 70% tighter than the 3.0 ACH50 code requirement. 

The second builder was a midsize residential builder with multiple 

developments in the Minneapolis-St. Paul metropolitan area. This builder 

already had a high quality of air sealing with four of their homes, with 

xi
manual sealing testing of 0.9–2.0 ACH50 during the 

initial assessment. Four homes were sealed for this 

builder, including one demonstration. The sealing 

demonstration performed at the end of construction was 

extremely successful. The house leakage was reduced 

from 0.7 ACH50 to 0.35 ACH50. The remaining three 

homes were sealed at a similar stage of construction as 

the first builder, before drywall was installed and after 

reinforced poly was placed at the second-floor ceiling. 

The aerosol sealing successfully reduced the house 

leakage by more than 70%. The end-of-construction 

testing for four of the homes showed an average air 

leakage of 0.8 ACH50 compared to 1.4 ACH50 for the 

control homes that were not sealed with aerosol. 

The project also included homes for four additional 

builders that had a type of construction or an air sealing 

approach that was used somewhat often in Minnesota 

that had not already been included in the houses of the 

first two builders. This included houses with slabon-grade foundations, flat roofs, and spray foam wall 

insulation. The sealing was successful in each of these 

cases, sealing nearly 80% of the leakage and achieving an average leakage 

of 0.8 ACH50 at the end of construction. 

Builder Interviews

The builders who participated in this study were interviewed after 

completion of the project to get their feedback on the advantages 

and disadvantages of aerosol sealing and how they could see it being 

incorporated into the construction process. The builders in Minnesota 

generally saw the value of the aerosol sealing service to get their homes 

well below code. Additionally, they identified sealing processes and 

materials that could potentially be removed when applying aerosol sealing, 

but they were hesitant to change their construction methods for a small 

number of their production houses. The primary concern was around vapor 

intrusion, which has been mitigated in part by using poly wrap on the 

interior of the home. Removing poly wrap was one suggestion, but one 

xii
builder mentioned that they already deal with a number of warranty issues 

that include moisture intrusion and would be concerned about removing 

that product. 

The California builders had a very different perspective, considering that 

the California Building Energy Efficiency Standards do not require a 

specific level of measured air leakage. Instead, there is a process through 

which the state inspects air sealing processes in the home, and based on 

that process it is assumed that the builders achieve 5.0 ACH50 for their 

homes. There are performance credits 

and utility incentives for verifying 

that their homes are getting below 5.0 

ACH50; however, the builders perceived 

that these benefits did not justify the 

additional cost of air sealing. If the 

models used to evaluate the performance 

of a home design associated more 

energy savings to building envelope 

sealing, then there could be costeffective tradeoffs that builders could 

use to justify the additional cost (i.e., 

downsized heating, ventilating, and airconditioning [HVAC] equipment).

Energy Savings

Energy savings from air sealing homes 

in the United States is highly dependent on climate zone. The project 

team performed a BEoptTM analysis that looked at the impact on heating 

and cooling energy use when sealing a 2,400-ft2 home in 16 U.S. climate 

zones. The results showed that colder climates had the highest source of 

energy savings, with 18% total savings in Fairbanks, Alaska (climate zone 

8), when sealing the home from the B10 Benchmark of 7.0 ACH50 to 2.0 

ACH50. Climate zones 4A, 5A, 5B, 6A, 6B, and 7 achieved total energy 

savings of 10% or higher in the same scenario, whereas the remaining 

climate zones saved 1%–8%. The savings ranged from 1%–10% when 

sealing homes from 5.0 ACH50 to 2.0 ACH50.

xiii
The primary driver for energy savings is reduced heating energy use in 

the homes, which is why colder climates show a higher percentage of 

savings. Cooling energy use for climate zones 3B-CA, 3C, 4C, 5B, 6B, 

7, and 8 went up due to the reduced infiltration during periods when the 

air temperature outside was cooler than inside during the 

cooling season; however, the relative amount of energy used 

for cooling was small compared to that for heating. Only one 

climate zone (3B-CA) showed an increase in total electricity 

energy use for the home. Opening the windows in the cooling 

season at times when the outdoor air is cooler than inside 

would minimize or eliminate increased cooling energy use.

Conclusions and Recommendations

Aerosol envelope sealing was very effective at sealing air 

leaks in new homes. Many of the demonstrations resulted in a 

tightness below 1.0 ACH50, which is well below the California 

and Minnesota Energy Code requirements of 5.0 ACH50

and 3.0 ACH50, respectively. The technology demonstrated 

versatility in sealing homes at various stages of construction, 

including before and after drywall is installed. Even with 

changes to installation protocols, the process consistently 

reduced envelope leakage by 70% or more when evaluating 

the leakage before and after sealing.

The aerosol envelope sealing process produced tighter homes 

and demonstrated a potential opportunity for cost savings in 

the construction process. A review of the standard air sealing 

efforts performed by U.S. builders shows several areas where 

efforts can be reduced or eliminated by applying aerosol 

sealing. By reducing other sealing work, builders can: (1) 

minimize material used for sealing a building, because aerosol 

sealing only applies material where leaks are present; (2) 

reduce the possibility of redundant sealing (e.g., sealing on 

both external and internal wall surfaces) while ensuring a 

continuous air barrier is applied; and (3) reduce the number 

of trades involved in the air sealing process so that the 

responsibility for creating a successful air barrier is clearly 

xiv
defined; fewer trades need to be trained and supervised; and less time is 

wasted sealing leaks that do not impact envelope leakage.

This research has demonstrated that builders can use the aerosol sealing 

technology to meet their air leakage targets without requiring close 

attention to detailed air sealing work. The technology seals smaller, 

distributed leaks in a home very efficiently, and these leaks are harder to 

address with conventional sealing techniques. Builders still have concerns 

about cost and a hesitancy to reduce current sealing efforts, but the ability 

for the aerosol sealing process to meet even the most stringent leakage 

targets gives builders the confidence that their air leakage goals can be 

met without fundamental changes to their regular construction practices. 

As codes become more stringent, it is expected that builders will be more 

likely to adopt the aerosol sealing technology as a cost-effective tool for 

meeting future air leakage goals.

xv
Aerosol Envelope Sealing of New Residences

xvi

Table of Contents

1 Introduction ............................................................................................................................. 1

2 Background ............................................................................................................................. 2

2.1 Development of the Aerosol Envelope Sealing Method .................................................. 4

2.1.1 Envelope Sealing of the Honda Smart Home ........................................................... 6

2.1.2 Production-Scale New Home Envelope Sealing....................................................... 8

2.1.3 Aerosol Sealing Commercialization ....................................................................... 10

2.2 Non-Energy Impacts ...................................................................................................... 10

2.3 Envelope Air Leakage Requirements ............................................................................. 11

2.3.1 International and Minnesota Energy Conservation Codes ...................................... 11

2.3.2 California Energy Code .......................................................................................... 12

3 Objectives ............................................................................................................................. 13

4 Methodology ......................................................................................................................... 16

4.1 House Selection Criteria................................................................................................. 16

4.2 Technical Approach ....................................................................................................... 17

4.3 Envelope Leakage Assessment ...................................................................................... 19

4.3.1 House Envelope Leakage Test ................................................................................ 20

4.3.2 Visual Inspection .................................................................................................... 21

4.3.3 Individual Leakage Sites ......................................................................................... 22

4.3.4 Guarded Leakage Test of Triplex Units .................................................................. 23

4.3.5 Infrared Inspection .................................................................................................. 25

4.3.6 Sealing Cost Estimates ............................................................................................ 25

5 Results and Discussion ......................................................................................................... 27

5.1 California Houses ........................................................................................................... 29

5.1.1 Unvented Attics: Phase I ......................................................................................... 29

5.1.2 Unvented Attics: Phase II ....................................................................................... 34

5.1.3 Unvented Attics: Discussion ................................................................................... 38

5.1.4 Vented Attics .......................................................................................................... 39

5.2 Minnesota Houses .......................................................................................................... 44

5.2.1 First Minnesota Builder (#3) ................................................................................... 46

5.2.2 Second Minnesota Builder (#4) .............................................................................. 62
Aerosol Envelope Sealing of New Residences

xvii

5.2.3 Phase I Aerosol Sealing .......................................................................................... 63

5.2.4 Phase II Aerosol Sealing ......................................................................................... 64

5.2.5 End-of-Construction Leakage ................................................................................. 65

5.2.6 Minnesota Builders 5–8 .......................................................................................... 65

5.3 Illinois Triplex ................................................................................................................ 71

5.3.1 End-of-Construction Leakage ................................................................................. 77

5.4 Builder Interviews .......................................................................................................... 78

5.5 Energy Modeling ............................................................................................................ 86

5.5.1 Energy Savings ....................................................................................................... 88

6 Conclusions and Recommendations ..................................................................................... 92

References ..................................................................................................................................... 95

Appendix A. Builder Interview Script and Questions .................................................................. 98

Appendix B. Code Requirements for Vapor Retarders and Air Barriers ................................... 100

Appendix C. Air Sealing Assessment Tables ............................................................................. 106

Appendix D. Content for the Building America Solution Center ............................................... 111
Aerosol Envelope Sealing of New Residences

xviii

List of Figures

Figure 1. Iterative approach to evaluating aerosol sealing options ................................................ ix

Figure 2. Measured envelope leakage of new homes in six states; the red dashed lines indicate 

the code requirement....................................................................................................................... 3

Figure 3. Distribution of envelope leakage of new homes in Maryland ......................................... 4

Figure 4. The progression of the sealing process from the start (left) to the end (right) ................ 5

Figure 5. Photos of the Honda Smart Home before aerosol envelope sealing application ............. 6

Figure 6. Photos of aerosol sealing installation on a single-family home, including examples of 

seals formed .................................................................................................................................... 7

Figure 7. Summary of results from the aerosol envelope sealing demonstration in the Honda 

Smart Home .................................................................................................................................... 8

Figure 8. Iterative approach to evaluate aerosol sealing options .................................................. 19

Figure 9. Test equipment configuration for a compartmentalization leakage test. ....................... 23

Figure 10. Test equipment configuration for guarded leakage test .............................................. 24

Figure 11. Photos of homes sealed under Option A showing open-cell spray foam at roof deck 

(left) and rim joist (right) .............................................................................................................. 30

Figure 12. Sealing profile for both houses under Option A .......................................................... 30

Figure 13. Photos of houses sealed under Option B ..................................................................... 32

Figure 14. Sealing profile for both houses sealed under Option B (pre-foam) ............................. 32

Figure 15. Air leakage results summary for all homes at each stage of the process .................... 33

Figure 16. Large gaps at eaves between foam and roof structure were sealed prior to aerosol 

sealing ........................................................................................................................................... 34

Figure 17. Bibs attached to roof deck left hanging (left); photo of home sealed with ridged foam 

on exterior (right) .......................................................................................................................... 35

Figure 18. Air barrier wrap above drywall to seal house attic from garage attic ......................... 36

Figure 19. Sealing profile for both houses sealed for Phase II with California Builder 2 ............ 37

Figure 20. Phase II air leakage results for all homes, including end of construction ................... 38

Figure 21. Air leakage results summary for all homes for Phase I and II at each stage of process

....................................................................................................................................................... 39

Figure 22. State of vented attic homes at time of sealing ............................................................. 40

Figure 23. Aerosol equipment set up in garage with kerosene heater (left); houses 10 and 11 

sealed during rain (right) ............................................................................................................... 41

Figure 24. Additional preparation required in houses 9, 10, and 11 to protect installed trim, 

including baseboards and shelves (left) and windowsills (right) .................................................. 41

Figure 25. Sealing profile for all five homes with vented attics sealed with California Builder A

....................................................................................................................................................... 42

Figure 26. Air leakage results for all vented attic homes, including end of construction ............ 43

Figure 27. Damaged seal in electrical outlet after aerosol sealing installation ............................. 44

Figure 28. Closed-cell spray foam at rim joist and duct penetrations (left); caulk at seams where 

wood is joined (right) .................................................................................................................... 45
Aerosol Envelope Sealing of New Residences

xix

Figure 29. Can foam at wire penetrations (left); foam gasket/caulk at sill plate and airtight 

electric box (right)......................................................................................................................... 46

Figure 30. Interior poly sheet on top floor ceilings and exterior walls ......................................... 46

Figure 31. Typical air sealing details: can foam around bottom plate duct and electrical 

penetration (left), airtight electric box at exterior wall and caulk bottom plate/subfloor (middle), 

and can foam at plumbing penetration and caulk between framing ............................................. 47

Figure 32. Temporary sealing preparations: shower base, 1-in. holes in subfloor over garage, and 

exhaust fan outlet .......................................................................................................................... 48

Figure 33. Manual sealing prior to aerosol: poly on second floor ceiling, foam at electrical 

penetrations to garage, and foam gap at top of garage drywall .................................................... 48

Figure 34. Sealing profile for Minnesota Builder 3 (House #12) demonstration sealing ............. 49

Figure 35. Example aerosol seals: gap between drywall sheets (left), gap between framing and 

sheathing (middle), and rim joist gaps (right) ............................................................................... 50

Figure 36. Sealing profile for the first four houses in Minnesota Builder 3’s Phase I ................. 53

Figure 37. Air leakage results for Minnesota Builder 3................................................................ 55

Figure 38. Example aerosol seals: between framing (left); between sill plate/sheathing; between 

sill plate/subfloor .......................................................................................................................... 55

Figure 39. Sealing profile for House #14 (no wall insulation) and #15 (insulated) ..................... 57

Figure 40. Poly sheet pulled away from framing .......................................................................... 58

Figure 41. Sealing profile for two Phase II houses ....................................................................... 60

Figure 42. Sealing profile for three houses for Minnesota Builder #4 ......................................... 62

Figure 43. Air leakage results for Minnesota Builder #4.............................................................. 64

Figure 44. Sealing profile for Minnesota Builder 5 (House #23), 6 (#24), and 8 (#26) ............... 67

Figure 45. Air leakage results for Minnesota Builders 5–8 .......................................................... 68

Figure 46. Sealing profile for Minnesota Builder #7 (House #25) ............................................... 70

Figure 47. Sealing profile for Minnesota Builder #8 house (#26) ................................................ 71

Figure 48. Sealing profile for Illinois Triplex ............................................................................... 74

Figure 49. Air leakage results for Illinois triplex .......................................................................... 75

Figure 50. Builder-reported typical (top) and target (bottom) leakage rates ................................ 79

Figure 51. Biggest challenge to using aerosol sealing .................................................................. 80

Figure 52. Current sealing that could be eliminated ..................................................................... 82

Figure 53. Best type of construction for aerosol sealing .............................................................. 83

Figure 54. Energy-efficient home marketing ................................................................................ 84

Figure 55. Beneficial information for home buyers...................................................................... 85

Figure 56. Use home comfort and/or energy efficiency as talking point with potential 

homeowners .................................................................................................................................. 86

Figure 57. Geometry of home used for infiltration modeling ....................................................... 88

Figure 58. Total energy savings from reducing air leakage in the model home in each U.S. 

climate zone .................................................................................................................................. 89
Aerosol Envelope Sealing of New Residences

xx

Figure 59. Cooling energy savings from reducing air leakage in the model home in each U.S. 

climate zone .................................................................................................................................. 90

Figure 60. Heating energy savings from reducing air leakage in the model home in each U.S. 

climate zone .................................................................................................................................. 90

Figure 61. Cooling energy intensity reduction from reducing air leakage in the model home in 

each U.S. climate zone .................................................................................................................. 91

Figure 62. Heating energy intensity reduction from reducing air leakage in the model home in 

each U.S. climate zone .................................................................................................................. 91

Figure 63. Aerosol sealing process ............................................................................................. 112

Figure 64. Aerosol fog from spray head ..................................................................................... 113

Figure 65. Aerosol sealant build-up on edge of leak .................................................................. 114

Figure 66. Blower door, sealant pump, and sealant setup in attached garage ............................ 114

Figure 67. Temporary cover over sprinkler head........................................................................ 115

Figure 68. Temporary cover over open plumbing pipes ............................................................. 115

Figure 69. Temporary cover over tub and plumbing fixture ...................................................... 116

Figure 70. Seal (gray material) formed between gap in foam .................................................... 117

Figure 71. Seal around electric box on exterior wall .................................................................. 117

Figure 72. Seal between electrical box and drywall; the seal on the sides of the box is made 

further back in the crevice and not visible on the surface ........................................................... 118

Figure 73. Seal between plumbing penetration and drywall ....................................................... 118

Figure 74. Seal gap between framing ......................................................................................... 119

Figure 75. Seal between sheathing and framing ......................................................................... 119
Aerosol Envelope Sealing of New Residences

xxi

List of Tables

Table 1. Summary of Aerosol Envelope Sealing Results ............................................................... 9

Table 2. Summary of Time Required for Each Step in Sealing Process ...................................... 10

Table 3. Visual Inspection Checklist: Categories and Components ............................................. 22

Table 4. Key Characteristics and Leakage Results for Aerosol-Sealed Residences ..................... 28

Table 5. Time and Materials Used to Manually Seal Homes Prior to Aerosol Sealing ............... 31

Table 6. Summary of Phase I Sealing Results .............................................................................. 33

Table 7. Summary Table of Aerosol Sealing Results: Phase II—Before Drywall ....................... 37

Table 8. Summary Table of Aerosol Sealing Results ................................................................... 42

Table 9. Current Air Sealing That Could Possibly Be Eliminated With Aerosol Sealing ........... 51

Table 10. Summary of Minnesota Builder 3 Sealing Results ....................................................... 54

Table 11. Summary of Minnesota Builder 4 Phase I Sealing Results .......................................... 63

Table 12. Summary of Sealing Results for Minnesota Builders 5–8 ............................................ 67

Table 13. Summary of Sealing Results for Illinois Triplex .......................................................... 74

Table 14. Detailed Illinois Triplex Leakage ................................................................................. 76

Table 15. Benefits of Using Aerosol Sealing................................................................................ 81

Table 16. Table R702.7.1: Class III Vapor Retarders Permitted For the Following .................. 102

Table 17. Table R402.4.1.1: Air Barrier and Insulation Installation Criteria ............................. 104

Table 18. California: Air Unvented Attics With Spray Foam Insulation ................................... 106

Table 19. California: Air Unvented Attics With Netted Insulation ............................................ 107

Table 20. California: Vented Attics ............................................................................................ 108

Table 21. First Minnesota Builder (#3)....................................................................................... 109

Table 22. Second Minnesota Builder (#4) .................................................................................. 110
Aerosol Envelope Sealing of New Residences

1 

1 Introduction

In many parts of the United States, house envelopes are notoriously leaky with unintended flows 

between conditioned and unconditioned spaces that result in additional space heating and cooling 

equipment loads. Although voluntary codes and standards for envelope tightness have existed for 

decades, only recently have these codes included mandatory envelope leakage requirements with 

verification by performance testing. Builders now need to integrate envelope sealing into their 

construction process. Current state-of-the-art methods for envelope air sealing rely on contractor 

personnel to manually seal typical leakage locations. The achieved airtightness levels can be 

highly variable and are based on the time allotted, accessibility of leaks, as well as the vigilance 

and experience of the contractor who performs the work. Although mid-construction leakage 

testing and diagnostics can help identify air barrier deficiencies earlier in the construction 

process, it is common for airtightness verification to be performed by a different contractor after 

the sealing and after the construction is mostly or entirely complete. This provides limited 

opportunity for feedback on the effectiveness of the air sealing, making it difficult for the sealing 

contractor to ensure that a specific level of leakage has been achieved. If the house leakage is 

greater than acceptable, additional sealing at later stages of construction is more expensive and 

may not be possible or effective. 

The aerosol envelope sealing technology developed by the Western Cooling Efficiency Center 

(WCEC) at UC Davis uses an automated method to satisfy the envelope sealing requirement. 

The process involves pressurizing the building using a standard blower door for an hour or two 

while multiple spray nozzles are used to disperse an aerosol sealant “fog” to the building interior. 

As air escapes the building through leaks in the envelope, the sealant particles are carried to the 

leaks where they impact and stick, sealing the leaks. The blower door is used to facilitate the 

sealing process, and provide real-time feedback and a permanent record of the sealing. The 

technology is thus capable of simultaneously measuring, locating, and sealing leaks in a building. 

At the start of this project, the WCEC technology was in the early stages of commercialization. 

The project team worked directly with builders to identify the best stages for incorporating 

aerosol sealing, from the perspectives of cost, performance, and seamless integration into the 

construction process. In addition to producing tighter houses, conventional sealing methods were 

evaluated to determine whether they could be eliminated or reduced to further improve costeffectiveness. A stepwise, iterative process was used with multiple builders, so that lessons 

learned from the first houses could be applied to later ones. The ultimate outcome of this project 

was to provide builders with procedures to easily integrate the aerosol sealing technique into 

standard construction practices. This will economically produce more consistent sealing 

performance and improved house airtightness to reliably meet stringent air leakage requirements. 
Aerosol Envelope Sealing of New Residences

2 

2 Background

The residential sector is responsible for about 23% of energy use in the United States, and 43% 

of that is due to heating and cooling (DOE 2014). For homes, 29% of space conditioning use is 

due to air infiltration—which means that about 12% of total use, or 2.85 quads, is due to air 

infiltration (DOE 2014). In many parts of the United States, this unintended air infiltration results 

in excess space heating and cooling equipment energy consumption. For example, the 135,000 

U.S. homes in Lawrence Berkeley National Laboratory’s Residential Leakage Database (ResDB) 

had a geometric mean leakage of 11 air changes per hour at a pressure difference of 50 pascals 

(ACH50) (Chan et al. 2013). 

Although voluntary standards for measured envelope tightness have existed for decades, these 

have only recently become a code requirement in some states, and tightness requirements are 

typically moderate. The 2009 version of the International Energy Conservation Code (ICC 2009) 

included an option for measured envelope air leakage testing less than 7.0 ACH50. The 2012 

version changed to a mandatory testing requirement with leakage less than 3.0 or 5.0 ACH50

depending on climate zone. A 2015 Department of Energy (DOE) six-state residential energy 

code study (DOE 2015) reported that for the five states with a code tightness requirement of 5.0 

or 7.0 ACH50, the state level compliance ranged from 70% to 97% (see Figure 2). For five states 

combined, there was a relatively high compliance rate of 87%. For the state of Maryland, which 

had recently implemented a lower requirement of 3.0 ACH50, the compliance rate was only 

48%—almost a third of the houses exceeded the code requirement by 50% or more (i.e., 4.5 

ACH50), and none of the houses had a leakage less than 1.9 ACH50 (Figure 3). In addition, only 

10% of the houses in the six states would have met the DOE Zero Energy Ready tightness 

requirement of 1.5 to 3.0 ACH50 (DOE 2019).1 

The results suggest that although mainstream contractors can achieve 5.0 or 7.0 ACH50, they are 

often not able to seal houses to a required tightness level of 3.0 ACH50, and that there is 

significant potential for tighter new houses with better sealing methods. Custom homebuilders 

can meet the Passive House standard of 0.6 ACH50, but this typically requires comprehensive 

sealing methods and quality control that could be achieved more easily with aerosol sealing. 

Aerosol sealing has the potential produce tight homes with reduced labor and material costs 

compared to conventional sealing, in addition to reducing contractor training and quality control 

for assuring that target house tightness values are achieved. This would reduce the need for 

skilled or experienced labor. 

1 The requirement is 3 in climate zones 1 and 2, 2.5 in zones 3 and 4, 2 in zones 5 to 7, and 1.5 in zone 8.
Aerosol Envelope Sealing of New Residences

3 

Figure 2. Measured envelope leakage of new homes in six states; the red dashed lines indicate the code 

requirement

Source: Building Energy Codes Program, Single Family Residential Energy Code Field Study, DOE 2015
Aerosol Envelope Sealing of New Residences

4 

Figure 3. Distribution of envelope leakage of new homes in Maryland

Source: Building Energy Codes Program, Single Family Residential Energy Code Field Study, DOE 2015

2.1 Development of the Aerosol Envelope Sealing Method

Aerosol sealing has been used successfully for residential duct sealing for more than 15 years, 

where it has been shown to seal duct leaks with a width of up to 5/8 in. (Modera et al. 1996). 

This technology was adapted by the WCEC for sealing leaks in the building envelope. The 

process involves pressurizing the building while dispersing an aerosol sealant “fog” to the 

building interior (see Figure 4). As air escapes the building through leaks in the envelope, the 

sealant particles are carried to the leaks where they make contact and stick, sealing the leaks. The 

sealant particles require an impact to adhere to a surface, so sealant material does not deposit on 

walls or ceilings except for at leak sites; sealant will settle onto horizontal surfaces due to 

gravity, so to avoid unwanted deposition these surfaces should be covered. Initial proof-ofconcept testing of the aerosol sealing process showed excellent results, sealing 40 in.2 of leakage 

in a small-scale enclosure in less than 10 minutes (Harrington and Modera 2012). 
Aerosol Envelope Sealing of New Residences

5 

Figure 4. The progression of the sealing process from the start (left) to the end (right)

When the process is applied to envelopes, all openings not intended to be sealed are blocked with 

tape or plastic (e.g., exhaust ducts, gaps around doors, and open plumbing connections). 

Depending on the condition of the house during application, horizontal surfaces such as floors 

and countertops may need to be covered with plastic to protect them from sealant that settles 

during the process. There is usually no noticeable deposition on vertical surfaces or on the 

underside of horizontal surfaces. A standard blower door fan is used to pressurize the house, and 

provides real-time feedback and a permanent record of the sealing that occurred. 

The sealant used for this project is a diluted version of a synthetic acrylic elastomeric material 

used as a spray or roll-on exterior air barrier. The sealant is GREENGUARD Gold Certified, 

meaning that it meets the strict certification criteria required for use in California schools and 

healthcare facilities. The sealant is tested according to various ASTM standards; however, 

because the sealant is atomized, the contractor should wear appropriate personal protective 

equipment and avoid entering the building during installation if possible. If entering the building 

is necessary, the contractor should wear a fitted respirator to prevent breathing the aerosol. No 

one else should be in the building during the sealing. When the installation is complete, the 

remaining aerosol is flushed out of the home by continuing to pressurize the space for several 

minutes after stopping the sealant injection.

Subsequent field demonstration projects showed the viability of the technology in larger spaces 

and practical application in real buildings. Because this project focused on new home 

construction, the following sections describe two single-family field demonstrations. However, 

there have also been demonstrations of the technology for multifamily applications (Bohac et al. 

2016; Maxwell et al. 2015), showing the potential for larger-scale application of the technology 

to different building types as well as modularity of the process for isolating individual 

compartments within a building. 
Aerosol Envelope Sealing of New Residences

6 

2.1.1 Envelope Sealing of the Honda Smart Home

Several projects were completed during the development of the aerosol sealing method, 

including work on the Honda Smart Home in Davis, California. The Honda Smart Home is a net

zero energy, two-story single-family home built to showcase some of the most advanced 

strategies to reduce the carbon footprint of U.S. homes. WCEC worked with Honda Motor 

Company to design the mechanical systems for the home and to demonstrate the aerosol 

envelope sealing process to reduce building shell leakage for better ventilation control and lower 

infiltration loads. 

This building was initially sealed using standard methods, and the following photos show areas 

where the aerosol sealant found and sealed leaks that had not been properly sealed with foam and 

caulk. A demonstration of the aerosol envelope sealing process on the Honda Smart Home 

achieved a reduction in building air leakage from 5.5 ACH50 to 1.0 ACH50.

2

 Photographs from 

this installation, including examples of seals formed, are shown in Figure 5 and Figure 6. The 

ultimate goal was to meet the very aggressive Passive House standard of 0.6 ACH50 (Passive 

House Institute 2016), which requires that the air barrier be applied to the external building 

envelope. 

Figure 5. Photos of the Honda Smart Home before aerosol envelope sealing application

2 These envelope sealing results have not been published.
Aerosol Envelope Sealing of New Residences

7 

Figure 6. Photos of aerosol sealing installation on a single-family home, including examples of seals formed

The contractor was asked to use standard methods to seal leaks with a gap width greater than 

0.25 in. (smallest dimension), because the time required to aerosol seal a leak has been shown to 

increase with the square of the smallest dimension (length or width) of the leak (e.g., it takes four 

times longer to seal a leak that is 0.5 in. across than to seal a leak that is 0.25 in. across). Figure 7

summarizes the results of the demonstration, highlighting the three discrete phases in the sealing 

process. The first aerosol sealing application used an airless nozzle injection system with five 

injection points and without any temperature/humidity control. This injection reduced the 

building leakage from 4.2 ACH50 to 2.6 ACH50. After the first application, three contractors 

spent 24 person-hours attempting to further seal the building manually with expanding foam and 

caulk, resulting in an almost negligible impact on the overall tightness of the building shell. 

Finally, the aerosol envelope sealing process was applied again, this time using air-atomization 

nozzles and temperature/humidity control. That process reduced the building leakage from 2.6 

ACH50 to 0.8 ACH50 in about 4 hours of total injection time. In summary, the Honda Smart 

Home demonstration revealed the advantage of using the aerosol envelope sealing process over 

standard manual sealing methods. Relying on manual sealing to accomplish the level of 

airtightness desired would have required a substantial amount of time and labor. 
Aerosol Envelope Sealing of New Residences

8 

Figure 7. Summary of results from the aerosol envelope sealing demonstration in the Honda Smart Home

This demonstration provided a superb comparison of the performance difference between airless 

and air-atomization nozzles, as well as the impact of temperature/humidity control. Researchers 

found that while the airless atomization nozzles created a uniform particle size distribution, the 

air-atomization nozzles projected the aerosol with more initial momentum, allowing the aerosol 

to better fill the building space and promote evaporation of water from the sealant particles. 

However, the largest performance improvement resulted from controlling the relative humidity 

within the space. This was accomplished during the air-atomization application by simply 

heating the inlet air and controlling the liquid sealant flow rate. Evaporation of water contained 

in the sealant mixture is critical to allow the particles to reach the proper size and to adhere to 

leak sites.

In subsequent demonstrations, the performance of the air-atomization system significantly

improved as work was expanded to multiple injection points, compared to the single injector 

nozzle that had to be moved around in the Honda Smart Home. 

2.1.2 Production-Scale New Home Envelope Sealing

Another Building America-funded project was conducted to evaluate production-scale envelope 

sealing of new single-family homes (Harrington and Springer 2015). Table 1 presents the house 

leakage measurements performed pre- and post-aerosol sealing. The envelope leakage of the 

houses was reduced by 62% to 85%, with an average of 74%. Because the process was applied at 

a rough-in stage of new construction, it would be expected that a significant amount of the 

3.0

4.2

2.6 2.6

0.8

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

2012 IECC Pre Test 1 Post Test 1 Pre Test 2 Post Test 2

ACH50

Manual sealing accomplished by 3 contractors over 8 hours
Aerosol Envelope Sealing of New Residences

9 

existing leakage would be sealed manually in later stages of construction, the exception being 

duct leakage. The leakage data presented in Table 1 show the leakage measurement performed 

with HVAC ducts blocked and large holes temporarily covered. 

Table 1. Summary of Aerosol Envelope Sealing Results

Test # Pre-Sealing 

Leakage (ACH50) 

Post-Sealing 

Leakage (ACH50) 

Leakage Reduction 

(%)

1 9.1 3.4 62%

2 13.7 5.0 63%

3 11.5 1.7 85%

4 8.5 1.8 79%

5 12.4 2.5 80%

6 13.2 3.2 76%

Average 11.4 2.5 74%

The time required for setup, sealing, and cleanup was closely tracked. Most of the installation 

crew was the same for each installation. The process required an average of 11 person-hours to 

complete (see Table 2). It is reasonable to assume that with experienced personnel and 

commercialized equipment, the time required could be reduced to two people working 4 to 5 

hours. 
Aerosol Envelope Sealing of New Residences

10

Table 2. Summary of Time Required for Each Step in Sealing Process

Test # # Floors

Floor Area 

(ft2) 

Time Required (person-hrs)

Setup Sealing Cleanup Total

1 2 3,550 6.3 1.5 5.0 12.8

2 1 2,019 5.9 1.4 3.4 10.6

3 1 2,324 6.7 1.2 4.2 12.1

4 2 3,550 6.9 1.9* 4.0 12.8

5 1 2,324 3.5 1.4 1.9 6.8

6 1 2,324 4.6 1.3 3.4 9.3

Average 1.3 2,682 5.7 1.4 3.7 10.7

* The air compressor ran out of fuel, causing a pause in the sealing.

2.1.3 Aerosol Sealing Commercialization

Following the success of initial demonstrations of the aerosol sealing process, WCEC pursued a 

licensing agreement with the sealing company Aeroseal. In 2014, UC Davis’s intellectual 

property office marketed the process to look for companies interested in licensing the 

technology. Aeroseal beat out several other entities based on their proposed business model for 

the technology. The aerosol envelope sealing technology was officially licensed to Aeroseal 

in 2016 and received the International Air-Conditioning, Heating, Refrigerating Expo 

(known as AHR Expo) “Product of the Year” award. It also received the 2018 International 

Builders’ Show “Best in Show” and “Most Innovative Building Product” awards. The 

technology is being commercialized under the name AeroBarrier. There are currently more 

than 75 dealers in the United States and Canada.

2.2 Non-Energy Impacts

In addition to lower energy costs from reduced heating and cooling loads, a tighter house 

envelope may have numerous other effects: 

• The control of air movement with a tight assembly is necessary for proper moisture 

control. High-R building envelope assemblies are commonly designed to withstand 

moisture diffusion through the assembly. However, water vapor diffusion is often an 

insignificant source of envelope moisture transport (Straube 2007). Moisture 

condensation from winter exfiltrating air and summer infiltrating air through air leaks in 

wall and other envelope cavities is one of the two major sources of moisture in abovegrade enclosures (rain is the other). In other words, “vapor is principally transported by 

air flow not by vapor diffusion” (Lstiburek 2015). Aerosol sealing of envelope air leaks 
Aerosol Envelope Sealing of New Residences

11

will reduce the convective movement of air and moisture through envelope cavities. This 

will help assure that high-R enclosures perform as predicted, therefore improving wall 

moisture control and reducing risks for long-term moisture damage.

• A tighter envelope reduces air infiltration, which can improve occupant comfort by 

reducing drafts. Reducing infiltration can improve indoor air quality by reducing the 

intrusion of outdoor air contaminants into the house. For example, Logue et al.’s (2012) 

estimate of the health impact of indoor air pollutants found that particulate matter 

(PM2.5), acrolein, and formaldehyde accounted for more than 80% of the health impact 

(e.g., disability-adjusted life years lost), and that indoor PM2.5 is due to both indoor 

sources and infiltration of outdoor PM2.5. Reducing outdoor PM2.5 infiltration and 

improved filtration of indoor air can greatly reduce indoor PM2.5. However, air 

infiltration can significantly reduce concentrations of pollutants that are predominantly 

due to indoor sources when there is not sufficient mechanical ventilation. Mechanical 

ventilation is required for the Minnesota and California houses in this study, and in 

Minnesota the ventilation system must be balanced. This project did not monitor indoor 

pollutant levels to evaluate the impact of house tightness and mechanical ventilation 

system operation, as that was beyond the project scope. 

• A tighter envelope can create greater house depressurization when exhaust fans and 

appliances are operated. This can lead to combustion spillage issues for natural and 

induced draft combustion appliances. However, builders are typically aware of this 

concern and have not included natural or induced draft combustion appliances in 

moderately tight or tighter houses. For example, power and direct vent combustion 

appliances are now the norm for Minnesota new construction. 

2.3 Envelope Air Leakage Requirements

2.3.1 International and Minnesota Energy Conservation Codes

The 2009 version of the International Energy Conservation Code (IECC 2009) was the first 

version to include envelope air leakage testing. Air sealing details could be confirmed with 

visual inspections or an air leakage test performed to confirm that the leakage is less than 7.0 

ACH50. In 2012, the International Energy Conservation Code (IECC) changed the envelope 

leakage test from being an option to a requirement (IECC 2012): 

R402.4.1.2 Testing. The building or dwelling unit shall be tested and verified as having an air 

leakage rate of not exceeding 5 air changes per hour in Climate Zones 1 and 2, and 3 air changes 

per hour in Climate Zones 3 through 8. Testing shall be conducted with a blower door at a 

pressure of 0.2 inches water gauge (50 Pa). Where required by the code official, testing shall be 

conducted by an approved third party. A written report of the results of the test shall be signed by 

the party conducting the test and provided to the code official. Testing shall be performed at any 

time after creation of all penetrations of the building thermal envelope. 
Aerosol Envelope Sealing of New Residences

12

The 2015 and 2018 versions (IECC 2015 and IECC 2018) of the testing and leakage requirement 

is identical to 2012 version, except the phrase “with a blower door” is replaced with “in 

accordance with ASTM E 779 or ASTM E 1827 and reported...” 

A Minnesota state law was enacted in 1975 to require building design and construction standards 

consistent with the most efficient use of energy (Minnesota Department of Labor and Industry 

2017). In response, an energy code became effective on January 30, 1976, as part of the state 

building code. In 1979, individual counties outside of the seven-county Minneapolis-St. Paul 

area as well as incorporated cities with populations of less than 2,500 were given the option of 

enforcing a statewide building code. Many elected to have no enforcement within their area. 

Currently, enforcement occurs for about 80% of the population base. In 2015, Minnesota adopted 

the 2012 version of the International Energy Conservation Code with state amendments. Section 

R402.4.1.2 was adopted without amendments. Because Minnesota is in climate zones 6 and 7, all 

new single-family houses must be tested for envelope leakage and have an air leakage rate no 

greater than 3.0 ACH50. 

A majority of the homes built in Minnesota are served by utilities that have residential new 

construction energy efficiency programs. In general, the programs provide a tiered financial 

incentive for high-efficiency houses based on a modeled comparison of the house’s annual 

energy use vs. the use for the same house that only meets code-minimum requirements. 

Reducing the envelope leakage to below the code-required level of 3.0 ACH50 will make it more 

likely that a house will qualify for the program and produce a higher incentive. For example, the 

current Xcel Energy Efficient New Home Construction program provides incentives for houses 

that exceed Minnesota’s energy code and baseline requirements by at least 10% (Xcel 2019). For 

natural gas heated houses, the incentive starts at $250 and increases to $2,000 for houses with 

total energy savings that are at least 35% above the baseline. 

2.3.2 California Energy Code

California’s Title 24 building codes have been around for more than 40 years and reduce 

building energy consumption in the state. The code is updated on a three-year cycle, with 2019 

code going into effect in January 2020. Title 24 code has yet to require specific levels of air 

leakage in new single-family homes. The default value used in the compliance modeling 

software is 5.0 ACH50, and builders can earn additional energy credits by reducing leakage 

below 5.0 ACH50. Although air leakage testing is not required for standard construction, air 

leakage testing is required when claiming credits for reducing air leakage below the default 

value. Additionally, California utilities offer incentives for builders achieving a highperformance home. The California Advanced Home Program provides builders with up to 

$1,950 in incentives for reducing energy use compared to the baseline model, with an additional 

$100–$300 for reducing building air leakage. 
Aerosol Envelope Sealing of New Residences

13

3 Objectives

Almost all previous new construction applications of aerosol sealing involved applying the 

sealant after wall and ceiling drywall was installed and taped. Aerosol sealing had been used to 

augment manual sealing methods used to create a tight envelope. This process resulted in limited 

surface preparation, an air barrier at interior surfaces, and 60% to 90% improvements in 

envelope tightness. This project was designed to address a number of questions to optimize the 

application of aerosol sealing for the single-family new construction process:

• In what situations is it effective to perform aerosol sealing prior to drywall?

Performing the aerosol sealing while the interior surface of the exterior wall sheathing is 

still exposed (i.e., before insulation and drywall is installed) creates an air barrier at the 

sheathing. Because a large fraction of the seals will be encased in the wall cavity after the 

drywall is installed, the seals will be well protected for the remainder of the construction 

process. Seals encased in cavities may have greater long-term durability, but that was not 

studied as part of this project.3 In order to perform pre-drywall aerosol sealing, an air 

barrier must be in place at the top of the house, and that may not occur until the ceiling 

drywall is installed. That may require modifications to the builder’s construction process. 

If this is feasible, there would be a trade-off between any negative impact on the 

construction process and the benefit of the aerosol sealing occurring at the exterior wall 

sheathing. 

As noted previously, the two major sources of wall moisture are rain and condensation 

from winter exfiltrating air and summer infiltrating air through air leaks (Straube 2007). 

A tighter envelope will reduce the convective movement of air and moisture from the 

inside to the outside (or vice versa) of the envelope regardless of whether the air barrier is 

located at the exterior or interior portion of the envelope. However, air can move into and 

out of a wall cavity from the same side of the cavity. Wind-washing occurs when outside 

air enters one section of the wall and exits back to the outside through another due to 

differences in wind-induced pressure at the different locations. An air barrier located at 

the exterior portion of the envelope will help reduce wind-washing, which can be a 

concern for air-conditioned residences in hot-humid climates. 

Pre-drywall aerosol sealing is not the only approach that creates an air barrier at the 

exterior portion of walls. Exterior air barriers can be created with sealed house wraps and 

exterior sheathing sealed with joint tapes, liquid-applied membranes, or fully adhered 

membranes. The drawback to exterior air barriers is that air can move into and out of 

cavities from the inside of the house, leading to the potential of condensation occurring 

on the exterior sheathing under cold ambient conditions. However, significant pressure 

3 Long-term sealant durability is an important issue that was studied in a separate WCEC project (Modera and 

Harrington 2018). That project measured the change in house leakage from the time the sealant is applied to the end 

of the construction process.
Aerosol Envelope Sealing of New Residences

14

differences between envelope cavities and the house interior are only likely to occur 

when cavities are used as ducts or leaky ducts are located in envelope cavities.

• In what situations is it effective to perform aerosol sealing after drywall? The 

amount of construction work completed before aerosol sealing impacts sealing costs and 

envelope tightness. Sealing immediately after drywall installation minimizes surface 

preparation and clean-up times, but maintaining the achieved tightness requires manual 

sealing of any additional penetrations to the air barrier or disturbances to the aerosol 

seals. The additional penetrations can be due to additional electrical (e.g., recessed can 

lights), HVAC (e.g., exhaust fans), or plumbing (e.g., shower fixtures) work. Completed 

seals can be disturbed by numerous construction activities that come in contact with the 

seals, including final wiring of devices in electric boxes and installing trim. Delaying the 

aerosol sealing reduces manual sealing and increases the labor and material costs for 

protecting any finished horizontal surfaces that are in place when the sealing is 

performed. The optimal time for the aerosol sealing depends on the trade-off between 

manual sealing and surface protection costs. 

• What conventional sealing can be eliminated? Aerosol sealing is highly effective at 

sealing narrow diffuse envelope leaks, producing tightness levels well below code 

requirements. The cost-effectiveness of aerosol sealing can be improved by eliminating 

conventional manual sealing methods, particularly those used to seal small gaps in air 

barrier penetrations and joints between sections of air barriers. For example, minor leaks 

that are sealed by caulk or foam are good candidates to be sealed by the aerosol method 

when applied at the appropriate stage of construction. Spray foam insulation of rim joists 

could potentially be replaced by aerosol sealing and less expensive batt insulation and 

vapor retarder. The aerosol sealing would provide the air barrier, so the vapor retarder 

would not need to be air sealed. Aerosol sealing has the potential to reduce labor and 

material costs for conventional sealing, in addition to reducing contractor training and 

quality control for assuring that code required tightness is achieved.

• Can aerosol sealing address “challenge” areas? Another opportunity is to examine 

specific sections of the air barrier that are often a challenge (e.g., areas with numerous 

penetrations, surfaces that do not intersect at right angles, and staircases or other framing 

that interrupt the air barrier surface) to determine ways that the aerosol method can more 

reliably and effectively seal those sections. Aerosol sealing of single-family new 

construction houses has been performed on a limited sample of houses. Not all types of 

challenge areas have been included in previous studies. This project performed aerosol 

sealing on a greater variety of challenge areas.

• Can the aerosol sealing process be improved? Experience from aerosol envelope 

sealing of the test houses in this project helped improve aerosol sealing protocols and 

equipment. The process in place at the start of the project evolved with feedback from 

additional field demonstrations. There had been recent, significant improvements to allow 
Aerosol Envelope Sealing of New Residences

15

for automated control of each component. It was expected that automated variation of the 

injection rate would more reliably produce the desired relative humidity of the inside air 

while reducing technician oversight. Experience from test houses helped refine the 

automation process and equipment. Feedback provided additional guidance on issues 

such as injection nozzle placement and the maximum and minimum areas for each 

nozzle. Finally, for many homes, aerosol sealing continued after the code required or 

target leakage was achieved. When the sealing rate was above a specified level, the 

sealing continued to determine the feasibility and cost-effectiveness of sealing beyond 

code requirements.
Aerosol Envelope Sealing of New Residences

16

4 Methodology

This project provided the research needed to successfully integrate aerosol envelope sealing into 

the home building process. The project team worked directly with builders to identify the best 

stages for incorporating aerosol sealing, from the perspectives of net cost, performance, and ease

of integration into the construction process. The cost of the aerosol sealing and resulting house 

tightness was documented for a sample of houses and compared to a similar group of houses 

using conventional sealing methods. Conventional sealing methods were evaluated to determine 

whether they could be eliminated or reduced to further improve cost-effectiveness while still 

achieving the required house tightness. For typical builders, the tightness goal is the level 

required by code—5.0 ACH50 is the assumed building airtightness in California when following 

the prescriptive sealing process, and 3.0 ACH50 is the code requirement in Minnesota. These 

were the target values for the two California builders and most of the Minnesota builders, but 

two of the Minnesota builders had a target of 1.0 ACH50, and the project had a stretch goal of 0.6 

ACH50 for all of the Minnesota builders. The different levels of required tightness helped 

identify the difference in sealing approaches (i.e., the extent of conventional sealing and quality 

control) needed to achieve each level. The results should better inform sealing approaches 

needed to achieve tightness levels required for high-performance houses. 

4.1 House Selection Criteria

The objective was to work with national and local production home builders that use common 

construction methods so that results would be applicable to a large percentage of new 

construction houses. The number of houses sealed for this project was not expected to provide a 

statistically representative sample to determine the distribution of house tightness for various 

house types. Instead, the number of houses was expected to determine the feasibility of achieving 

a tightness target for the aerosol sealing applied at a particular time of construction and 

eliminating some conventional sealing. Standard air leakage test methods were used to 

accurately measure pre/post changes in leakage. Systematic inspection procedures documented 

the location and quality of the seal of individual envelope air leaks. 

The project did not apply a rigid definition of “common construction,” but the team expected that 

the houses would be site-built, wood-framed, cavity-insulated structures with conventional 

sheathings, typical exterior water management (such as building paper or house wrap), and 

interior air barrier and vapor retarder (such as poly or smart vapor retarder). Researchers wanted 

the houses to include air sealing details that were well suited for aerosol sealing as well as

“challenge” areas where aerosol sealing may have a competitive price advantage over 

conventional sealing. These areas could include rim joists that are being sealed with spray foam, 

bump outs, cantilevers, tuck-under garages, and attached garages.
Aerosol Envelope Sealing of New Residences

17

The initial target was single-family detached houses. Houses with the following construction 

types were not included: 

1. Structural insulated panels 

2. Exterior air barrier using self-adhered modified bituminous membrane sheets 

3. Exterior air barrier using liquid-applied sealant

4. Exterior air barrier system using precast, site-cast or tilt-up concrete panel. 

Builders selected for the project needed to have a sufficient number of houses under construction 

that met the construction type requirements described above. The first builder in each state 

needed to provide seven houses of similar construction that could be sealed within a 10-month 

period and four control houses of similar type that would be constructed during the same period. 

In order to provide scheduling flexibility, it was expected that the builder would be constructing 

at least 40 to 60 houses per year. The second builder in each state could be a lower-volume 

builder—they only needed to provide four houses to be sealed over 10 months and four control 

houses. Each builder needed to be willing to provide sealing cost estimates and to eliminate some 

sealing methods from their test houses. Researchers initially recruited builders who attended a 

builder kick-off meeting and others who expressed interest in the aerosol envelope sealing 

technology. 

4.2 Technical Approach

The project team used a stepwise, iterative approach to develop and refine aerosol envelope 

sealing guidelines. This approach allowed experience from an initial set of houses sealed for the 

first builder to refine sealing methods for a second set of houses for the same builder. The work 

was staged so that as the second set of houses was being completed for the first builder, the 

planning started for an initial set of houses for the second builder. Parallel efforts were used for 

two builders in California and two in Minnesota. The work in Minnesota was later expanded to 

include an additional five builders to evaluate sealing methods for types of construction that were 

not included with the first two builders. 

The multistep process for each builder is shown in Figure 8 and described in more detail here: 

1. Hold initial meeting and assess houses. The project team met with the builder to 

discuss their typical manual air sealing practices and review the field work timeline. 

The project team then performed air leakage assessments and tests on two or three 

representative houses.4 At least one of the houses was at the pre-drywall stage of 

construction, after the insulation and air sealing had been completed. When feasible, 

the second house was at the framing inspection stage to identify air leakage locations, 

and the third house was close to occupancy. Additionally, the builder provided 

4 Section 4.3 Envelope Leakage Assessment provides a description of the assessments.
Aerosol Envelope Sealing of New Residences

18

available air leakage test results for houses built within the past year that were in 

close proximity and type to the houses used in the study. 

2. Demonstrate aerosol sealing. Aerosol envelope sealing was demonstrated on one 

house that was under construction. It was preferred that the demonstration house 

would be at the same stage of construction as that for the first set of houses for the 

builder. Appropriate builder representatives were on-site to observe the sealing 

process and participate in the visual identification of remaining leakage after the 

sealing was complete. The demonstration was not performed for builders that already 

had experience with the aerosol envelope sealing process. 

3. Develop options for aerosol sealing. Project team members met with builders to 

review findings and identify sealing options. The options considered the findings 

from the baseline leakage assessment, the initial feedback from the builder, and the 

results from sealing work conducted on houses already sealed for the project. The 

protocol considered the stage of construction during which the aerosol sealing was

applied and the conventional sealing that was eliminated. Although the sealing 

options were specific to each builder, experience from one builder was applied to 

improving the process for the others. Two sealing options were identified for the first 

builder in each state, and one option was used for the other builders. 

4. Perform aerosol sealing and evaluate impact. Each of the aerosol sealing options 

was applied and evaluated. Assessments of the aerosol-sealed houses were performed 

(1) prior to sealing, (2) immediately after sealing, and (3) after construction was 

complete. An assessment was also conducted after construction was complete for 

each control house that received conventional sealing. Sealing experience, 

pre/post/finished assessments, and pre/post/finished leakage tests of aerosol and 

conventionally sealed houses were summarized in a report for the builder’s houses. 

5. Review results with builder and generate updated sealing option. An in-person 

meeting was conducted with the builder to get feedback from the first set of houses 

sealed. The project team and builder considered the advantages and disadvantages of 

the sealing options. The sealing options were revised as necessary to establish an 

updated approach. 

6. Perform aerosol sealing and evaluate impact. The revised aerosol sealing options 

were applied and evaluated. Similar to Step 4, assessments of the aerosol-sealed 

houses were performed (1) prior to sealing, (2) immediately after sealing, and (3) 

after construction is complete. An assessment was also conducted after construction 

was complete for each control house that received conventional sealing. Sealing 

experience, pre/post/finished assessments, and pre/post/finished leakage tests of 

aerosol and conventionally sealed houses were summarized.
Aerosol Envelope Sealing of New Residences

19

7. Review results with builder. An end-of-project interview was conducted with each

builder to get their feedback about the aerosol envelope sealing process. The 

objectives were to get the builder’s perceptions of the advantages and disadvantages 

about the process as well as how they see it being incorporated into their construction 

process. Project staff conducted the interviews using 12 open-ended questions to 

initiate an informal discussion. The script and questions are included in Appendix A. 

For the first builder in each state, four or five houses were sealed in Step 4 to accommodate two 

different sealing options. The refined method for Step 6 was applied to two or three houses. It 

was expected that the sealing options would be narrowed for the second builders in each state. 

For those builders, one or two houses were sealed for Step 4 and another two or three for Step 6. 

It was expected that at least 11 houses would be sealed in each state. Ultimately, the sealing 

included 11 houses in California, 15 houses in Minnesota,5

 and one triplex in Illinois. The 

experience from all the sealing was used to identify best sealing practices based on the type of 

construction and builder’s air sealing goals. 

Figure 8. Iterative approach to evaluate aerosol sealing options

4.3 Envelope Leakage Assessment

Short-term house assessments used quantitative and qualitative methods to evaluate envelope 

leakage at three points in the construction process: (1) prior to aerosol sealing, (2) after aerosol 

sealing, and (3) after construction is complete. In addition, staff worked with AeroBarrier to 

estimate the cost of aerosol sealing and with the builders to determine avoided cost of 

conventional sealing. No continuous monitoring was conducted for this project.

Every house envelope air leakage assessment included a quantitative whole-house envelope 

leakage (e.g., blower door) test and qualitative visual assessment of leakage. When weather 

conditions and house availability allowed, an infrared scan was used to assist with leakage 

identification. Additionally, the leakage of individual spots or sections of the envelope was

measured by guarded leakage tests, or individual leakage site tests. These additional 

measurements were conducted when conditions allowed, and there was significant value in the 

more detailed information. The following subsections provide a description of the assessment 

methods. 

5 The 15 houses in Minnesota included two demonstration houses.
Aerosol Envelope Sealing of New Residences

20

4.3.1 House Envelope Leakage Test 

A whole-house envelope leakage test (i.e., blower door test) was the primary method for 

quantifying house leakage. Almost all of the tests were conducted as a multipoint test in 

accordance with either the RESNET 380 Procedure for Measuring Air Tightness of Building 

Enclosure (RESNET/ICC 380 2016) or ASTM E 779-10 Standard Test Method for Determining 

Air Leakage Rate by Fan Pressurization (2010).

6

 All tests of California houses and end-ofconstruction tests of Minnesota houses were conducted as depressurization tests, because a 

depressurization test is most commonly used to measure house envelope leakage. The pre- and 

post-aerosol sealing tests of Minnesota houses were conducted as pressurization tests to avoid 

damaging the exposed poly sheets on the second floor ceilings.7 The envelope leakage was 

reported as the leakage rate at a pressure difference of 50 Pa (CFM50). The leakage was divided 

by the house volume to generate a normalized house leakage in units of air changes per hour at 

50 Pa (ACH50).

The house setup and test procedures were followed as specified in the test standards. However, 

in some cases, the house mechanical and plumbing systems were not complete at the time of the 

aerosol sealing. For the pre- and post-aerosol sealing tests it was necessary to temporarily seal 

openings such as clothes dryer exhaust vents, heat recovery ventilator terminations and inlets not 

connected to the system, exhaust fan ducts, supply ventilation ducts, and open plumbing waste 

pipes without filled traps. Except for inlet and exhaust ducts without dampers of continuously 

operating ventilation systems, the temporary seals in place at the time of the aerosol sealing were 

not in place for the end-of-construction tests. Consequently, for each house the setup and type of 

test (e.g., pressurization or depressurization) was always the same for the pre- and post-aerosol 

sealing tests. There was no change in test procedure that biased the reduction in house leakage 

due to aerosol sealing. However, the unsealed openings could have been a source of increased 

leakage at the end-of-construction test, and for the Minnesota houses the switch from a 

pressurization to depressurization test could have impacted the leakage measurement. All 

baseline and depressurization or pressurization measurements were averaged over a period of at 

least 15 seconds. Each multipoint leakage test typically included eight points for pressure 

differences ranging from 20 to 60 Pa. The change in pressure between points was usually 10 Pa, 

with 5 Pa differences for measurements closer to 50 Pa and a duplicate measurement at 50 Pa. A 

common sequence was to record measurements at 20, 30, 40, 45, 50, 50, 55, and 60 Pa. The 

baseline pressure difference was recorded before and after the fan-on points. The elevation, 

inside air temperature, and outside air temperature were used to adjust the flow rates to standard 

conditions. The multipoint analysis specified by ASTM E 779-10 for a power law relationship 

was used to report the leakage flow rate at a pressure difference of 50 Pa.

6 A single-point test at 50 Pa was used to measure pre-aerosol sealing leakage for half of the Minnesota houses. The 

accuracy of the leakage at the start of the process was less important than the leakage after sealing and at the end of 

construction. 7 There were two houses where the poly sheeting was covered by drywall, but a pressurization test was performed 

for those houses so that the procedure was consistent for all Minnesota houses.
Aerosol Envelope Sealing of New Residences

21

The envelope leakage tests were conducted using two types of variable-speed calibrated test fans. 

The larger fan (TEC Model 3 fan) has a capacity from approximately 300 to 6,300 cfm, and the 

capacity of the smaller fan (TEC Duct Blaster) is approximately 10 to 1,500 cfm. The fans have 

a manufacturer-specified accuracy of 3% of the flow rate. Pressure measurements were 

performed using a two-channel digital micromanometer (TEC DG-1000 or DG-700) that was 

calibrated in accordance with manufacturer guidelines and has a specified accuracy of the greater 

of 0.15 Pa or 1.0% of the measurement. 

4.3.2 Visual Inspection

The visual inspections qualitatively evaluated the tightness of the house air barrier. The 

inspection included the use of a smoke puffer to help estimate the relative magnitude of the air 

leakage. Researchers developed a checklist of common leakage sites to guide the inspection 

process and provide structure to the results. The visual inspection checklist is based on the Air 

Leakage section of the EPA ENERGY STAR® Rater Field Checklist (EPA ENERGY STAR

2015) and the 2015 IECC Table R402.4.1.1 Air Barrier and Insulation Installation Air Barrier 

Criteria. 

Table 3 shows the seven categories and 26 components that were included in the checklist. The 

inspections provided information about the quality of sealing work (excellent, acceptable, poor, 

no attempt), who performed the sealing, what material was used, and the potential for aerosol 

sealing to replace traditional methods. A list of predefined responses was provided to reduce data 

collection time and aide the interpretation, normalization, and reporting of results. Field staff 

recorded notes and pictures of key sealing details. The results for one of the builders are included 

in Table 3, and Appendix C includes the results for all of the builders.
Aerosol Envelope Sealing of New Residences

22

Table 3. Visual Inspection Checklist: Categories and Components

Category Component Who Does 

Sealing?

Material Used for 

Sealing?

Can 

AeroBarrier 

Replace?

Quality 

of Seal 

Work

Ceiling/Attic

Attic access panels N/A Gasketed door No Excellent

Drop down stairs N/A N/A N/A N/A

Whole-house fans N/A N/A N/A N/A

Recessed lighting 

fixtures N/A Gasketed fixture Yes Excellent

Drop ceiling/soffit Insulation contractor Closed cell spray 

foam Yes Excellent

Walls

Exterior walls Insulation contractor Gasket/OSB N/A Excellent

Sill plate Carpentry contractor Gasket/OSB Yes Acceptable

Top plate Insulation contractor Gasket Yes Acceptable

Drywall to top plate Insulation contractor Gasket Yes Excellent

Interior partition wall to 

exterior wall

Carpentry contractor/ 

Insulation contractor

Solid blocking/

can foam Yes Excellent

Knee walls Carpentry contractor OSB N/A Excellent

Windows, 

Skylights and 

Doors

Rough openings Insulation contractor Can foam Yes Excellent

Rim Joists Insulation contractor Open-cell spray foam Yes Excellent

Shafts, 

Penetrations

to 

Unconditioned 

Spaces

Ducts Insulation contractor Can foam/

open-cell spray foam No Excellent

Flues Insulation contractor Can foam/

open-cell spray foam No Excellent

Shafts Insulation contractor Can foam/

open-cell spray foam No Excellent

Plumbing Insulation contractor Can foam/

open-cell spray foam Yes Excellent

Piping Insulation contractor Can foam/

open-cell spray foam Yes Excellent

Wiring Insulation contractor Can foam/

open-cell spray foam Yes Excellent

Exhaust fans Insulation contractor Can foam/

open-cell spray foam Yes Excellent

Other N/A N/A N/A N/A

Garage 

Separation 

Walls

Floor cavities aligned 

with garage separation 

walls

Carpentry contractor/ 

insulation contractor

Blocking/

open-cell spray foam No Excellent

Other

Shower/tub on exterior 

wall

Carpentry contractor/ 

insulation contractor

OSB/ 

open-cell spray foam Yes Excellent

Stair stringer on exterior 

wall N/A None Yes N/A

Fireplace on exterior wall N/A N/A N/A N/A

Electrical/low voltage 

boxes on exterior walls Insulation contractor Can foam/open-cell spray foam Yes Excellent

HVAC register boots that 

penetrate building 

thermal envelope

Insulation contractor Open-cell spray foam Yes N/A

4.3.3 Individual Leakage Sites

The leakage of individual isolated sites located on a flat surface can be measured by placing an 

airflow metering device over the area during a whole-house depressurization leakage test. This is 

an accepted method to measure the leakage of a variety of sites, including plumbing penetrations, 

duct penetrations, recessed light cans, and electric outlet boxes. A flow measurement device was 

placed over the leakage site at the house interior (e.g., wall or ceiling surface) while a blower 

door was used to depressurize the house to -50 Pa. Leakage flow rate measurements greater than 

10 cfm were conducted with a TEC FlowBlaster airflow device, a powered flow hood that 
Aerosol Envelope Sealing of New Residences

23

creates approximately zero pressure difference across the meter during the measurement. 

Consequently, the measured flow rate is the flow through the leak at the induced envelope 

pressure. A custom calibrated TEC Exhaust Fan Flow Meter was used for lower flow rates. An 

orifice plate with multiple 1-in. diameter holes was placed over the standard opening. The 

relationship between the pressure across the plate and the flow rate was determined for one and 

multiple open holes. For the leakage measurement, a sufficient number of holes were opened to 

minimize the pressure difference across the box while still providing a reasonably accurate 

measurement.

4.3.4 Guarded Leakage Test of Triplex Units

A compartmentalization air leakage test measured the total (exterior and interior) air leakage of 

the triplex units. The change in total leakage was the primary assessment to determine the impact 

of the air sealing on envelope leakage of the unit. A TEC Duct Blaster was installed in the 

hallway door of the unit being tested, and the adjoining units were opened to the hallway, which 

in turn was opened to the outside (see Figure 9). A multipoint leakage test was conducted in 

accordance with the RESNET 380 Procedure for Measuring Air Tightness of Building Enclosure 

(RESNET/ICC 380 2016). All tests (e.g., pre-aerosol sealing, post-aerosol sealing, and end of 

construction) were conducted as depressurization tests. The mechanical system penetrations 

(e.g., clothes dryer vent, exhaust fans, heat recovery ventilator ducts, combustion air) were 

configured according to RESNET 380. If an appliance or damper was not in place for the test, 

the opening was temporarily sealed. The envelope leakage was reported as the leakage rate at a 

pressure difference of 50 Pa (CFM50). The leakage was divided by the unit volume to generate a 

normalized leakage in units of air changes per hour at 50 Pa (ACH50), and was divided by the 

envelope surface area to generate a per area leakage (CFM50/ft2

). The compartmentalization test 

does not distinguish between the exterior and interior leakage. 

Figure 9. Test equipment configuration for a compartmentalization leakage test.

Figure from Paul Morin, TEC

dP= 50Pa
Aerosol Envelope Sealing of New Residences

24

A guarded air leakage test measured the air leakage through the exterior portion of the envelope. 

The diagram in Figure 10 shows the building and test equipment setup for conducting a guarded 

test of an individual unit (top/center) using additional fans located in a main entry. To measure 

the exterior leakage of the test unit, the main entry fans are operated to depressurize the whole 

building by 50 Pa. Except for the test unit, the hallway doors to all of the units are opened so that 

the building acts as a single zone. A blower door fan is located in the hallway door of the test 

unit. That fan is operated to maintain a zero pressure difference between the test unit and the 

hallway adjoining the test unit. With this configuration, the only airflow into the test unit is from 

the exterior. Consequently, the flow through the test fan in the unit is equal to the exterior 

envelope leakage of the unit. 

Figure 10. Test equipment configuration for guarded leakage test
Aerosol Envelope Sealing of New Residences

25

Figure from Paul Morin, TEC

There are no standards that provide a protocol for conducting guarded leakage tests. Procedures 

developed for a DOE-funded project to conduct whole-building guarded tests of low-rise 

multifamily buildings were adapted for this project. 

4.3.5 Infrared Inspection

An infrared scan assists in the identification of significant envelope air leaks. The infrared scan 

covers large sections of the enclosure surface in a relatively short amount of time to identify 

likely leakage locations. When an infrared scan was conducted for this research, it was typically 

performed from the house interior as a two-step process to differentiate between insulation 

deficiencies and envelope air leaks (ASTM E1186-17 2017). For the first step of the process, a 

scan of the interior surface of the envelope was performed with the house in “as-found” 

conditions. This documents thermal anomalies from insulation deficiencies (e.g., voids) and 

significant air leakage from wind and stack effects. The scan was then repeated with the house 

depressurized 15 to 25 Pa by a test fan. When the outside temperature was lower than the inside 

temperature, surfaces that were colder than observed during the initial scan indicated air leakage. 

When the outside air was warmer than inside, air leaks appeared as new warm spots. Depending 

on the sensitivity of the infrared camera and other variables (e.g., wind speed and solar heating 

of exterior surfaces), a difference in outdoor to indoor air temperature of at least 10°F was 

needed for the scan to be useful. Although an infrared scan cannot quantify air leakage, it is 

sometimes useful for quickly identifying leakage locations. Infrared scans were occasionally 

used in this research as a method for documenting envelope leakage, although aerosol sealing 

contractors do not typically use infrared scans for their sealing process. 

4.3.6 Sealing Cost Estimates

Sealing costs were estimated for both conventional and aerosol sealing methods in order to 

determine the potential cost savings of replacing some conventional sealing work with the 

aerosol sealing technology. Based on past experiences, it was expected that the cost breakdown 

for conventional sealing in a home would be difficult to determine. Subcontractor bids for work 

generally do not include the details on labor and materials for specific tasks related to air sealing. 

In addition, the sealing can be conducted by multiple trades (e.g., insulation/air sealer, drywall 

installer, carpenter, electrician, plumber, and siding installer), and the trade responsible for the 

sealing tasks can vary by builder. 

During the first round of builder meetings, there was a discussion of what sealing work is 

performed in a typical home. The research team conducted visual inspections of the leakage sites 

and asked the builder which trade was responsible for each of the sealing methods. The project 

staff estimated conventional sealing costs by speaking with the various trades responsible for air 

sealing work. 

Because aerosol sealing is now a commercialized service available from AeroBarrier dealers, 

AeroBarrier staff and the dealers who participated in this project were consulted regarding their 
Aerosol Envelope Sealing of New Residences

26

cost estimating strategy. In general, the cost is primarily based on the house floor area. Similar to 

many construction tasks, there are other variables that also impact aerosol sealing costs, 

including: (1) manual pre-sealing to be performed by the dealer, (2) extent of surface protection 

required prior to sealing, (3) air leakage target, (4) pre-sealing air leakage, (5) stage of 

construction, (6) the proximity of a second house so that two houses can be sealed on the same 

day, (7) travel time, (8) single-family versus multifamily, and (9) the number of houses or 

multifamily units to be sealed. Currently, AeroBarrier estimates that aerosol sealing cost ranges 

from $1 to $2 per square foot of floor area for typical new home construction. The range and 

typical time to perform aerosol sealing were estimated for a subset of the homes by recording the 

time required to prep, seal, and cleanup. 
Aerosol Envelope Sealing of New Residences

27

5 Results and Discussion

Aerosol sealing was performed on 11 houses in California, 15 houses in Minnesota, and a triplex 

in Illinois. Table 4 displays key characteristics and sealing results for the project residences. For 

the two builders in California and first two builders in Minnesota, the sealing work was first 

conducted on a group of one to four houses that were designated as the Phase I group. 

Experience gained from the Phase I houses was used to adjust sealing approaches or house 

characteristics for the group of Phase II houses. That work was performed for two builders in 

California on slab-on-grade houses with unvented and vented attics. The initial work with two 

builders in Minnesota for vented attic houses with basements was expanded to a total of six 

builders in order to help evaluate sealing methods for types of construction that were not 

included with the first two builders. Finally, a residence in Illinois was included to document the 

effectiveness of aerosol sealing process for slab-on-grade, two-story triplexes for which the 

builder historically had difficulty meeting an envelope leakage requirement. Table 4 also 

includes the stage of construction for the application of the aerosol sealing. In general, the 

sealing was either performed at a relatively early stage (e.g., before installation of wall insulation 

and drywall) or near the end of construction (e.g., post-drywall).
Aerosol Envelope Sealing of New Residences

28

Table 4. Key Characteristics and Leakage Results for Aerosol-Sealed Residences

House 

# 

Builder 

# 

Sealing 

Phase

Floor 

Area 

(ft2) 

Attic 

Type

Foundation 

Type

Const. 

Stage for 

Sealing

Aerosol 

Leakage 

Reduction

End 

Const. 

Leakage 

(ACH50)

Sealing 

Time 

(Hours)

CA

1 1 I-A 2,569 Unvented Slab 

PreDrywall & 

PostFoam

75% 1.24 1.6

2 1 I-A 2,032 Unvented Slab 

PreDrywall & 

PostFoam

73% 1.16 1.0

3 1 I-B 2,569 Unvented Slab 

PreDrywall & 

PreFoam

86% 1.00 3.1

4 1 I-B 2,223 Unvented Slab 

PreDrywall & 

PreFoam

84% 1.07 2.4

5 2 II 2,100 Unvented Slab PreDrywall 80% 1.77 1.1

6 2 II 1,900 Unvented Slab PreDrywall 81% 3.42 1.5

7 1 I 2,223 Vented Slab PostDrywall 80% 3.35 1.4

8 1 I 2,223 Vented Slab PostDrywall 80% 1.69 1.5

9 1 II 2,569 Vented Slab PostDrywall 54% 3.97 1.1

10 1 II 1,595 Vented Slab PostDrywall 70% * 0.9

11 1 II 1,595 Vented Slab PostDrywall 66% 3.26 1.1

MN

12 3 Demo 3,338 Vented Basement PreDrywall 84% 0.76 2.4

13 3 I-A 4,361 Vented Basement PreDrywall 72% 0.90 2.3

14 3 I-A 3,913 Vented Basement PreDrywall 82% 0.92 1.8

15 3 I-B 4,186 Vented Basement

PreDrywall & 

Post-Wall 

Insul

46% 0.82 4.8

16 3 I-B 4,428 Vented Basement

PreDrywall & 

Post-Wall 

Insul

66% ** 4.6

17 3 II 3,972 Vented Basement PreDrywall 83% 0.77 1.8

18 3 II 4,360 Vented Basement PreDrywall 79% 1.09 1.6

19 4 Demo 4,135 Vented Basement PostDrywall 50% 0.61 0.6

20 4 I 4,603 Vented Basement PreDrywall 78% 0.42 1.1
Aerosol Envelope Sealing of New Residences

29

21 4 II 3,698 Vented Basement PreDrywall 82% 1.07 2.1

22 4 II 3,243 Vented Basement PreDrywall 70% 1.08 1.2

23 5 I 2,592 Vented Basement PostDrywall 73% 0.96 1.5

24 6 I 2,074 Flat Roof Slab PreDrywall 74% 0.96 1.8

25 7 I 3,334 Vented Basement

PreDrywall & 

PreFoam

88% 0.70 2.0

26 8 I 3,882 Vented Basement PreDrywall 81% 0.77 1.2

IL

27 9 I 778 NA1 Slab PostDrywall 54% 3.82 1.5

28 9 I 778 NA Slab PostDrywall 52% 2.97 2.1

29 9 I 1,282 Flat Roof NA2 PostDrywall 73% 2.51 1.2

5.1 California Houses

The houses sealed in California were split into two groups: unvented attics and vented attics. The 

unvented attic design is not commonly adopted by home developers but results in significant 

performance credits for meeting California code energy requirements, whereas the vented attic 

design is much more common for single-family homes. The iterative approach for working with 

contractors differed slightly from the approach described in the Methodology section (see Figure 

8). Phase I for the homes with unvented attics was performed with California Builder 1, and 

Phase II was performed with California Builder 2. There were some differences in general 

construction style and insulation approach for the two builders, which impacted the aerosol 

sealing strategy. All homes sealed with vented attics were performed with California Builder 1. 

5.1.1 Unvented Attics: Phase I

The project team conducted visual inspections of homes under various stages of construction, 

from installation of exterior sheathing to the drywall stage. The inspections, which were based on 

the ENERGY STAR Rater checklist for building air sealing, showed a high quality of air sealing. 

The homes were designed with unvented attics and used open-cell spray foam at the rim joist and 

under the roof deck to both insulate and provide air sealing. After the initial assessment, the 

project team met with the builder and determined two options for applying the aerosol sealing. 

Four homes were sealed, two using Option A and two using Option B (described next). The 

homes were all two stories and ranged in size from 2,030–2,570 ft2

. 

Option A 

Aerosol envelope sealing for Option A occurred after open-cell spray foam was installed at the 

rim joist and below the roof deck, but prior to the installation of drywall on the walls and ceiling 

(see Figure 11). No additional sealing was performed prior to the aerosol sealing. The pre-sealing 

results showed air leakage of 4.39 and 3.47 ACH50 for the two homes during this stage of 

construction. 
Aerosol Envelope Sealing of New Residences

30

Figure 11. Photos of homes sealed under Option A showing open-cell spray foam at roof deck (left) and rim 

joist (right)

The aerosol sealing proved very successful. The overall time to seal each home, including prep 

and cleanup, took about 3 hours to complete. The leakage at the start of the sealing was between 

3.5 and 4.4 ACH50. Figure 12 shows the sealing profile for both sealing demonstrations under 

Option A. There were slight differences in the time required for sealing and the starting leakage 

rate, which is likely due to differences in the floorplan for the homes. For both houses, the rate of 

sealing is greatest at the start of the sealing and gradually decreases over time. The unique 

feature of aerosol sealing is that all leaks are sealed simultaneously as long as the sealant is 

dispersed uniformly though the house. Narrower leaks are quickly sealed, and wider leaks take 

longer to seal. The greater rate of sealing at the start of the process suggests that both houses had 

a large length of narrow gap leaks. The leakage dropped by 50% within 30 to 35 minutes. In both 

cases, the aerosol sealing reduced the leakage by about 75%, bringing them down to 1.11 and 

0.95 ACH50, which is roughly 80% below the California target of 5.0 ACH50. 

Figure 12. Sealing profile for both houses under Option A

0

200

400

600

800

1,000

1,200

1,400

1,600

0 10 20 30 40 50 60 70 80 90 100

House Leakage (CFM50)

Elapsed Time (minutes)

House #1 House #2
Aerosol Envelope Sealing of New Residences

31

Option B 

For Option B, the aerosol envelope sealing occurred before open-cell spray foam was installed 

and represents the first opportunity to seal the homes, because the building shell is largely 

complete (Figure 13). Some manual sealing prior to aerosol sealing was required to block larger 

penetrations that would not be sealed efficiently with the aerosol. The time and materials 

required to perform that sealing were documented. There were some issues coordinating the 

sealing demonstrations with the home builder, which led to gaps at the eaves of the home that 

would normally have been blocked prior to the aerosol sealing. Additionally, there was manual 

sealing of other large penetrations. In the first house (#3) the pre-sealing effort was focused 

primarily on penetrations that were much too large to seal with the aerosol technology, whereas

in the second house (#4), more care was taken to seal all gaps that were easily identifiable (could 

see daylight penetrating) regardless of whether the leak could be sealed with the aerosol 

technology. The time required and materials used are outlined in Table 5. 

Table 5. Time and Materials Used to Manually Seal Homes Prior to Aerosol Sealing

 Sealing Penetrations Sealing Gap at Eaves

Stage House 

# 

Time for Manual 

Sealing (personhrs.)Cans of 

Foam Used

Time for Manual 

Sealing (personhrs.)Cans of Foam 

Used

Pre-Foam 3 1.5 3 1.5 4 

Pre-Foam 4 4.5 6 1 4 

After the two pre-sealing efforts, the leakage of the homes was 15.14 ACH50 and 9.01 ACH50 for 

houses #3 and #4, respectively. Clearly, the additional manual sealing effort for House #4 

resulted in improved initial airtightness with an increased cost. Ultimately, builders and their 

AeroBarrier contractor need to evaluate the additional cost of manual sealing compared to the 

aerosol sealing performance differences and cost for their specific houses. 

The aerosol sealing proved very successful at this stage of construction. The sealing injection 

time increased from the sealing under Option A, requiring 2–3 hours to complete. The overall 

time to seal each home, including prep and cleanup, took 4–5 hours to complete. Due to slight 

changes in the manual pre-sealing efforts in each building, the leakage at the start of the sealing 

was around 5,800 CFM50 in one case and about 3,000 CFM50 in the other. Figure 14 shows the 

sealing profile for both sealing demonstrations under Option B. The rate of air sealing was faster 

at the beginning of the installation and slowed as the process continued. The aerosol sealing 

reduced the leakage in both cases by about 85%, bringing them down to 2.15 and 1.43 ACH50

before spray foam installation was installed. That is roughly 60%–70% below the California 

prescriptive target of 5.0 ACH50. 
Aerosol Envelope Sealing of New Residences

32

Figure 13. Photos of houses sealed under Option B

Another leakage test on each home was performed after the spray foam installation to determine 

the additional sealing due to the insulation. After spray foam, the measured air leakage of the 

homes were 1.25 and 1.06 ACH50, representing an additional leakage reduction of 6% and 4%, 

respectively, relative to the initial leakage of the homes. This result is only slightly higher than 

the result for using aerosol sealing after the spray foam installation under Option A. 

Figure 14. Sealing profile for both houses sealed under Option B (pre-foam)

Table 6 and Figure 15 provide a summary of all aerosol sealing results for the first round of tests 

for the Phase I homes. Overall, nearly 10,000 CFM50 of air leakage was sealed in 8 hours of total 

injection time over 2 days. The average airtightness achieved was 1.09 ACH50 before drywall 

was installed in the homes. Final air leakage tests were performed after the end of construction, 

showing very little change in air leakage (average of 1.12 ACH50). The homes sealed with 

aerosol sealing were 39% tighter than homes sealed with only conventional methods. All homes 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0 20 40 60 80 100 120 140 160 180 200

House Leakage (CFM50)

Elapsed Time (minutes)

House #3

House #4
Aerosol Envelope Sealing of New Residences

33

were under 2.0 ACH50, suggesting that the open-cell foam did a good job of sealing. Postoccupancy tests were not within the scope of this project. However, lab durability testing showed 

an overall increase of less than 0.1% of the sealed area when aerosol seals were subjected to 

1,900 cycles of 100 Pa pressure change (Modera and Harrington 2018). The sealant is a diluted 

version of a synthetic acrylic elastomeric material that is typically used as an exterior air barrier 

and is expected to “flex” with movement in building materials. 

Table 6. Summary of Phase I Sealing Results

Stage/

House 

# 

Floor 

Area 

(ft2) 

Volume 

(ft3) 

Pre-Seal Post-Seal After Foam

CFM50 ACH50 CFM50 ACH50

% 

Reduction CFM50 ACH50

% 

Reduction

PostFoam: 1 2,569 23,121 1,690 4.39 429 1.11 75%

PostFoam: 2 2,032 22,215 1,286 3.47 351 0.95 73%

PreFoam: 3 2,569 23,121 5,836 15.14 828 2.15 86% 483 1.25 42%

PreFoam: 4 2,223 20,007 3,005 9.01 477 1.43 84% 352 1.06 26%

Figure 15. Air leakage results summary for all homes at each stage of the process
Aerosol Envelope Sealing of New Residences

34

5.1.2 Unvented Attics: Phase II

Phase II of the aerosol sealing demonstrations aimed at further developing the air sealing 

approach for homes designed with unvented attics. The homes sealed for Phase II were built by a 

different builder (#2) in California than in Phase I, but many of the same sealing strategies were 

used by both builders. The Phase II homes were designed with blown-in cellulose insulation at 

the roof deck, which differed from the spray foam insulation used in the Phase I testing. In both 

cases the air barrier is formed at the roof deck. This allowed researchers to assess the airtightness 

achieved under both approaches. It is understood that spray foam does a better job than blown-in 

cellulose of sealing air leaks, in addition to providing insulation for the homes. The Phase II 

demonstrations assessed whether the aerosol sealing process could achieve high levels of 

airtightness without using spray foam insulation. 

Builder 2 for Phase II took some specific measures in order to facilitate the aerosol sealing in 

their homes. They modified the schedule to allow the insulation to be installed after exterior rigid 

foam as opposed to before, which would normally be the case. Additionally, the builder installed 

drywall earlier in the construction process than normal between the garage and the living space 

to complete the air barrier of the home (the garage is not typically included in air leakage 

assessments of homes). An air barrier wrap was installed to block the garage attic from the house 

attic. These modifications were fairly minor and could be avoided if aerosol sealing was planned 

for the homes at the design phase.

Based on our experience in Phase I, the exterior rigid foam was expected to close the gaps left at 

the eaves where the roof meets the wall; however, observations at homes for California Builder 2 

showed that some of the gaps were still larger than expected (Figure 16). The areas where large 

gaps existed were manually foamed by the aerosol contractor prior to the aerosol sealing process. 

The contractor was able to address this leakage in about 0.5 person-hours.

Figure 16. Large gaps at eaves between foam and roof structure were sealed prior to aerosol sealing

The aerosol envelope sealing demonstrations were completed by a local aerosol distributor on 

July 24–25, 2018, for houses located at a net zero energy community in Clovis, California. 
Aerosol Envelope Sealing of New Residences

35

Building America project team members Curtis Harrington and Daniel Reif were present, and 

they performed pre- and post-aerosol sealing air leakage testing as well as assisting with building 

preparation activities. Two single-story homes with attached garages were sealed and ranged in 

size from 1,900–2,100 ft2. Figure 17 shows the stage of construction the homes were in at the 

time of the aerosol sealing.

Figure 17. Bibs attached to roof deck left hanging (left); photo of home sealed with ridged foam on exterior 

(right)

During the initial pressurization for the first home, the team uncovered a significant air leak 

between the home and garage. It was not noticed initially, but was uncovered when the team had 

trouble pressurizing the home. The construction methods did not allow aerosol sealing to be 

applied without minor modifications and resulted in the builder having to install an air barrier 

wrap to block the garage attic from the home attic spaces (Figure 18). There was a relatively 

small section of this barrier that was not installed continuously up to the roof. The bib material 

for insulation and the house wrap looked similar, and in one section there was a significant leak 

through the porous bib netting. After identifying the leak path, the project team installed poly 

wrap to block the leak. 
Aerosol Envelope Sealing of New Residences

36

Figure 18. Air barrier wrap above drywall to seal house attic from garage attic

After addressing the bulk air leakage, the aerosol sealing process went very well. The sealing 

was conducted for about 1–1.5 hours. The overall time to seal each home including prep and 

cleanup was about 7 hours for the first home (due to the additional prep required to block the 

attic leak) and about 5 hours for the second home. The leakage of the homes started at 5,900 

CFM50 and 6,900 CFM50, and they were sealed by about 80% to 1,200 CFM50 and 1,300 CFM50, 

respectively. Figure 19 shows the sealing profiles for both homes sealed in Phase II, and the 

results of the air leakage tests performed by the Building America team are summarized in Table 

7.
Aerosol Envelope Sealing of New Residences

37

Figure 19. Sealing profile for both houses sealed for Phase II with California Builder 2

Table 7. Summary Table of Aerosol Sealing Results: Phase II—Before Drywall

Stage/

House #

Floor 

Area (ft2) 

Volume 

(ft3) 

Pre-Seal Post-Seal

CFM50 ACH50 CFM50 ACH50

% 

Reduction

Pre-Drywall: 5 2,100 26,250 5,906 13.50 1,193 2.73 80%

Pre-Drywall: 6 1,900 23,750 6,911 17.46 1,288 3.25 81%

Figure 20 presents the end-of-construction leakage results for homes sealed in Phase II. The 

homes with aerosol sealing were about 50% tighter than the baseline homes, with an average 

leakage of 2.6 ACH50 compared to 5.1 ACH50 for the homes not aerosol sealed. There was a 

significant difference between the leakages measured for the two homes with aerosol sealing. 

One home tested at 1.8 ACH50, whereas the other tested at 3.4 ACH50. The difference is 

attributed to the fact that the attic between the garage and the conditioned space were connected, 

and it was difficult to install an air barrier to deal with the bulk airflow path between them. A 

plastic barrier was installed to create the air barrier, but there was significant leakage around the 

plastic. The builder had not planned the design of the home around the use of aerosol sealing, so 

this issue could be avoided by using a different attic system design. In addition, the final leakage 

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

8,000

0 10 20 30 40 50 60 70 80 90 100

House Leakage (CFM50)

Elapsed Time (minutes)

House #6

House #5
Aerosol Envelope Sealing of New Residences

38

number for the leakier home was slightly higher than the post-sealing result, indicating that the 

work completed in the home after sealing (e.g., drywall, installing appliances and flooring) 

resulted in a net increase in building leakage. No other home sealed for the two phases of this 

project showed an increase in leakage after the aerosol sealing.

Figure 20. Phase II air leakage results for all homes, including end of construction

5.1.3 Unvented Attics: Discussion

Figure 21 presents the results from both phases of this project for aerosol work on homes 

designed with unvented attics. The results for the homes that used spray foam insulation showed 

generally tighter construction. The higher levels of air leakage for homes that used fibrous 

insulation was partly due to the differences in construction technique, such as the fact that in 

Phase I, California Builder 1 installed OSB around the entire building envelope. The air barrier 

wrap installed between the garage attic and the house attic was another source of leakage in 

homes in Phase II that were not sealed as effectively with the aerosol. One home sealed in Phase 

II had significant trouble getting bulk air leakage blocked prior to aerosol, and this home ended 

up with the highest leakage of the homes sealed. The construction approach taken by California 

Builder 2 resulted in leakier buildings in general, with the baseline homes that were sealed with 

conventional methods testing out at 5.1 ACH50. The aerosol process demonstrated the ability to 

seal one of the homes with fibrous insulation down to 1.8 ACH50, which is a significant 

improvement. This level of leakage roughly matches the airtightness achieved in the baseline 

homes for California Builder 1 using spray foam, suggesting that aerosol with fibrous insulation 

could be used in place of open-cell spray foam.

0

2

4

6

8

10

12

14

16

18

20

House #5 House #6 Baseline Baseline Baseline

House Leakage (ACH50)

Pre-Seal Post-Seal End-Construction
Aerosol Envelope Sealing of New Residences

39

Figure 21. Air leakage results summary for all homes for Phase I and II at each stage of process

5.1.4 Vented Attics

The next set of aerosol sealing looked at the application process for sealing homes with vented 

attics. The homes sealed in this final phase were built by the same builder from Phase I; some of 

the homes had the same floor plans as the homes with unvented attics. No spray foam insulation 

was used in these homes as a cost-saving measure by the builder. Instead, fiberglass and 

cellulose were used in the walls and above ceilings. The aerosol sealing was applied after 

drywall was installed, before wall texturing and after texturing and trim installation. No major 

changes were required to apply aerosol at this stage of construction. 

An air sealing assessment for California Builder 1 on homes designed with vented attics was 

performed by Curtis Harrington and Daniel Reif. Several houses in a subdivision in Lodi, 

California were inspected on May 17, 2018. The inspection results were identical to the unvented 

attic homes in Phase I, showing a high quality of air sealing. California Builder 1 stopped 

building homes with unvented attics due to low demand and to reduce costs. This and the 

insulation methods were the only major changes made in the design of these homes. Methods for 

sealing homes with vented attics during rough-in (before drywall is installed) were discussed 

with California Builder 1 during the site visit. Applying at that stage would have required 

installing drywall at the ceiling-attic interface to complete the bulk air barrier. This would be a 

major shift in standard practice for this builder and their contractors, and therefore was not 

performed for this project. The advantages of sealing before most of the drywall and insulation is 

installed is that seals would form at the exterior building shell, reducing the amount of air 

infiltration in the wall cavity. In addition, this would reduce the chance of seals getting damaged 
Aerosol Envelope Sealing of New Residences

40

from other work in the home (e.g., electrical work damaging seals formed on outlet boxes). 

Ultimately, it was decided that the best time to seal would be after drywall was taped. There is 

some flexibility at this stage that allows the sealing to occur after mud or after texture is 

installed. Sealing at the internal wall surface also minimizes moisture transfer into the wall 

cavity from inside sources. 

The aerosol demonstrations were completed by the same local aerosol distributor from Phase II 

of the unvented attic tests. One home was sealed each day on June 26, 2018, July 2, 2018, and 

January 4, 2019. Two homes were sealed on January 16, 2019, with a majority of the prep work 

completed the previous day. As in previous phases, Building America researchers were present 

to measure pre- and post-aerosol air leakage, and to assist with building prep. Three of the five 

homes sealed were two stories and 2,223–2,569 ft2

. The remaining two homes were one story 

and 1,595 ft2. Figure 22 shows the stage of construction the homes were in at the time of the 

aerosol installation.

 

Figure 22. State of vented attic homes at time of sealing

The final two homes were sealed during light rain showers (Figure 23). High humidity and very 

cold temperatures reduce the amount of sealant that can be injected due the limited capacity for 

water to be evaporated into the air, which reduces sealing rates. To supplement the electric 

resistance heaters used with the standard aerosol system, a kerosene forced air heater in the 

garage was placed at the fan inlet. While direct-fire heating adds some moisture to the space, the 

overall impact can reduce the relative humidity of the air under certain conditions, and the 

contractor had noticed positive results when using a kerosene heater to supplement the electric 

resistance heaters integrated in the aerosol equipment. The additional heat was used to increase 

the sealant injection rates and improve sealing time.
Aerosol Envelope Sealing of New Residences

41

Figure 23. Aerosol equipment set up in garage with kerosene heater (left); Houses #10 and #11 sealed 

during rain (right)

The overall time to seal each home including prep and cleanup was about 5 hours for the first 

two homes (houses #7 and #8). Total time for sealing, prep, and cleanup was 7 hours for the third 

home (#9), and 6 hours each for the fourth and fifth homes (#10 and #11). The last three homes 

required additional time to prep because some finishings were already installed, including 

windowsills, baseboards, and shelving in closets. These surfaces were temporarily covered 

during sealing to prevent sealant deposition, as shown in Figure 24. The sealing was conducted 

for about 1–1.5 hours in each home. Figure 25 shows the sealing profiles for all five homes with 

vented attics sealed, and the results of the air leakage tests performed by the Building America 

team are summarized in Table 8. 

Figure 24. Additional preparation required in Houses #9, #10, and #11 to protect installed trim, including 

baseboards and shelves (left) and windowsills (right)
Aerosol Envelope Sealing of New Residences

42

Figure 25. Sealing profile for all five homes with vented attics sealed with California Builder A

Table 8. Summary Table of Aerosol Sealing Results

Stage

Option House

Floor 

Area 

(ft2) 

Volume 

(ft3) 

Pre-Seal Post-Seal

CFM50 ACH50 CFM50 ACH50

% 

Reduction

After 

Drywall 7 2,223 20,007 2,480 7.44 499 1.50 80%

After 

Drywall 8 2,223 20,007 2,433 7.30 477 1.43 80%

After 

Drywall 9 2,569 23,121 1,918 4.98 890 2.31 54%

After 

Drywall 10 1,595 14,355 1,378 5.76 409 1.71 70%

After 

Drywall 11 1,595 14,355 1,130 4.72 386 1.62 66%

Figure 25 includes the house leakage after the aerosol sealing was completed (post-seal) and at 

the end of construction. Tests were not conducted at one home because the tenants moved in 

before the test could be conducted. In general, there was a significant increase in leakage from 

the end of the aerosol sealing to the end of construction, and that increase was somewhat greater 

than the increase for the unvented attic houses. A few sources for the increased leakage are fire 

0

500

1,000

1,500

2,000

2,500

3,000

0 10 20 30 40 50 60 70 80 90 100

House Leakage (CFM50)

Elapsed Time (minutes)

House #7

House #8

House #9

House #10

House #11
Aerosol Envelope Sealing of New Residences

43

sprinklers, backdraft dampers on exhaust systems, and electrical outlets. The sprinklers and 

dampers were blocked during the post-seal tests and would be an issue for conventionally sealed 

homes as well. Fire sprinklers are required in homes built in California, and air leakage 

measurements were taken on a small sample of sprinklers in the homes, showing an average air 

leakage of around 10 CFM50 each. Considering homes can have more than 10 sprinklers, this 

results in 100 CFM50 of leakage to the attic that cannot be sealed by any method because that 

would affect the functionality of the sprinkler. For homes with unvented attics, the air barrier is 

above the sprinkler at the roof deck so the air leakage of sprinklers to the unvented attic does not 

affect the overall leakage rate. Additional leakage was found through the backdraft dampers in 

the exhaust systems with 200–300 CFM50 of leakage. Seals formed in electrical outlets and 

switches showed visible signs of disruption from electrical work after sealing, but the air leakage 

testing showed it had a minimal impact on air leakage (Figure 26). Ultimately, homes sealed 

with aerosol were 33% tighter than the baseline homes. The aerosol-sealed homes ended up at 

3.1 ACH50 compared to the baseline homes at 4.6 ACH50. 

Figure 26. Air leakage results for all vented attic homes, including end of construction

0

1

2

3

4

5

6

7

8

House #7 House #8 House #9 House #10 House #11 Drywall

Baseline

Drywall

Baseline

Drywall

Baseline

House Leakage (ACH50)

Pre-Seal Post-Seal End-Construction
Aerosol Envelope Sealing of New Residences

44

Figure 27. Damaged seal in electrical outlet after aerosol sealing installation

5.2 Minnesota Houses

The field work in Minnesota started with two builders using the stepwise, iterative approach for 

evaluating sealing methods as described in the Methodology section. The number of builders was 

later expanded to include an additional four Minnesota builders to help evaluate sealing methods 

for types of construction that were not included with the first two builders. A total of 15 houses 

were sealed for the six builders. 

Almost all of the Minnesota houses had the following construction characteristics: 

• Vented attic, attached (typically tuck-under) garage, and poured concrete basement

• House wrap as the weather resistive barrier on the exterior of the wall sheathing

• Fiberglass or mineral wool batts in 2x6 exterior wall cavities

• Blown fiberglass or fiberglass batts at the ceiling in all attic spaces

• Code-required balanced ventilation most often served using an energy recovery ventilator 

or heat recovery ventilator. 

Deviations from these characteristics for individual buildings are noted in the descriptions of the 

results.

The houses were required to meet the Minnesota Energy Code envelope leakage requirement of 

3.0 ACH50 as measured with an envelope air leakage (i.e., blower door) test. The houses were 

typically participating in a utility energy efficiency program that provided tiered incentives for 
Aerosol Envelope Sealing of New Residences

45

modeled annual energy use below energy code minimum requirements. In order to meet the 

code-required envelope leakage and achieve higher utility program incentives, the builders 

typically used the following air sealing methods: 

• Closed-cell spray foam used to seal/insulate rim and band joists (Figure 28) 

• Caulk joints where wood framing meets on exterior walls and flooring (Figure 28 and 

Figure 29) 

• Electrical, plumbing, and other penetrations sealed with can foam (Figure 29) 

• Airtight electric boxes on exterior walls (Figure 29) 

• Interior 6-mil polyethylene sheeting with acoustical sealant on exterior walls; top floor 

ceiling serves as vapor retarder and air barrier (Figure 30). 

Most of the Minnesota builders in this project had a target to meet the energy code leakage 

requirement of 3.0 ACH50, but two of the builders had a target of 1.0 ACH50, and the project had 

a stretch goal of 0.6 ACH50 for all of the Minnesota builders. 

Figure 28. Closed-cell spray foam at rim joist and duct penetrations (left); caulk at seams where wood is 

joined (right)
Aerosol Envelope Sealing of New Residences

46

Figure 29. Can foam at wire penetrations (left); foam gasket/caulk at sill plate and airtight electric box (right)

Figure 30. Interior poly sheet on top floor ceilings and exterior walls

5.2.1 First Minnesota Builder (#3)

The first Minnesota builder was a large, national builder with multiple developments in the 

Minneapolis-St. Paul metropolitan area. Field inspections of two houses were conducted to 

qualitatively assess the envelope air barrier. One of the houses was at the rough-in stage of 

construction and the other was at the pre-drywall stage. The results from those inspections and 

experience from other houses constructed by this builder were used to generate the table of air 

sealing components included in Appendix C. Photos of a sample of the sealing details are shown 

in Figure 31. The inspections showed an overall high quality of air sealing. The level of quality 

for all except three components was either excellent (18) or not applicable (5). Only the sealing 

of the attic access panel was considered to be poor.8 This qualitative assessment is consistent 

with the air leakage test results from Home Energy Rating System (HERS) rater reports for four 

of the builder’s houses with similar floor plans. The envelope leakage of those four houses 

ranged from 1.19 to 1.47 ACH50. The average leakage of 1.31 ACH50 is 56% below the State of 

Minnesota code requirement of 3.0 ACH50. The reports indicated limited air sealing concerns 

8 The sealing is accomplished by the texture coat being applied to the ceiling. If someone were to use the access 

panel, the sealing will be broken. Code requires the attic hatch to be weatherstripped.
Aerosol Envelope Sealing of New Residences

47

with the following possible air leakage issues noted: fan housing, ceiling electric box, garage 

service door trim, front of game room leakage into cavity wall, attic access not sealed, and 

infrared indicating cold spots at the owner’s closet ceiling. 

Figure 31. Typical air sealing details: can foam around bottom plate duct and electrical penetration (left), 

airtight electric box at exterior wall and caulk bottom plate/subfloor (middle), and can foam at plumbing 

penetration and caulk between framing

Demonstration Aerosol Sealing 

A demonstration of the aerosol envelope sealing process was completed by AeroBarrier staff on 

May 30, 2017, for one of the builder’s houses. At that time almost all house envelope 

demonstration aerosol sealing had been performed near or at the end of construction. Aerosol 

sealing at that stage typically seals an air barrier that is at or near the interior surface of the 

envelope cavity. Because one of the project’s objectives was to evaluate sealing performed at 

various stages of construction, the house was sealed early in the construction process—soon after 

the exterior enclosure of the house was mostly complete. Applying the aerosol sealing at that 

stage of construction was expected to seal an air barrier at or near the exterior surface of the 

envelope cavity. That typically produces an air barrier at the sheathing and wood framing of 

exterior walls. The insulation, drywall, and rim joist spray foam had not been installed. Electrical 

and duct penetrations between floors and at exterior walls were sealed. In addition, foam had 

been sprayed in the gaps around almost all of the windows. Reinforced polyethylene sheets were 

installed on the second floor ceiling in order to complete the house air barrier and allow 

pressurization for the aerosol sealing to be performed. The sheets were caulked and stapled to the 

framing. The ceiling poly would typically have been installed at the same time that poly would 

be installed on the exterior walls. Consequently, the materials and amount of labor were not 

changed. The work was done somewhat out of sequence for their insulation subcontractor, and 

this would result in an added trip cost if the ceiling poly cannot be installed at the same time as 

other insulation and air sealing work. The following items were temporarily sealed: bathroom 

exhaust fan duct outlet, kitchen exhaust fan duct, energy recovery ventilator inlet and exhaust 
Aerosol Envelope Sealing of New Residences

48

ducts, 1-in. holes in the second floor bedroom subfloor9 above the garage, combustion air duct, 

furnace vent, water heater vent, sealed combustion gas fireplace vent, and clothes dryer vent. 

Photos of some of the sealing preparations and manual sealing are shown in Figure 32 and Figure 

33. 

Figure 32. Temporary sealing preparations: shower base, 1-in. holes in subfloor over garage, and exhaust fan 

outlet

Figure 33. Manual sealing prior to aerosol: poly on second floor ceiling, foam at electrical penetrations to 

garage, and foam gap at top of garage drywall

The aerosol envelope sealing proved very successful. As shown in Figure 34, the sealing was 

conducted for approximately 2.5 hours with a starting leakage of about 2,500 CFM50. However, 

some leaks between the garage and living area were manually sealed during the first 10 to 15 

minutes of the aerosol sealing. If it is assumed that 300 CFM50 sealing was due to the manual 

sealing, the “initial” house leakage for the aerosol sealing would have been approximately 2,200 

CFM50. The sealing was paused after 90 minutes; the leakage was 662 CFM50 at that time. The 

sealing continued for another 60 minutes. The red line in Figure 34 shows the rate of sealing. 

The sealing begins within 5 to 10 minutes after the house is pressurized and the sealant fog is 

dispersed. The rate of sealing starts at about 50 CFM50/min and slowly drops over time. It 

9

 1-in. holes were used during construction to move floor panels. Plastic caps were inserted later in construction.
Aerosol Envelope Sealing of New Residences

49

reaches 10 CFM50/min after about 1 hour and 15 minutes and drops to 5 CFM50/min after about 2 

hours. It is likely that a large number of narrow gaps are sealed quickly while the larger leaks 

take longer to fully seal. Photos of aerosols seals are shown in Figure 35. It is evident that most 

of the sealing occurs for long lengths of narrow gaps. 

A multipoint house leakage measurement at the end of the aerosol sealing resulted in a tightness 

of 358 CFM50 or 0.64 ACH50. The reduction of 84% is consistent with the reductions obtained 

for previous projects. This is 79% below the State of Minnesota code requirement of 3.0 ACH50. 

Additionally, it is 51% less than the average house tightness of 1.31 ACH50 for the four 

completed HERS rated houses and only 7% higher than the Passive House standard of 0.6 

ACH50. This very tight construction was achieved without the poly vapor/air barrier in place on 

the walls and without the spray foam insulation/air sealing of the rim joists. This suggests that 

the current level of house tightness of 1.3 ACH50 could be produced without much of the current 

air sealing when aerosol sealing is applied. 

Figure 34. Sealing profile for Minnesota Builder 3 (House #12) demonstration sealing
Aerosol Envelope Sealing of New Residences

50

Figure 35. Example aerosol seals: gap between drywall sheets (left), gap between framing and sheathing 

(middle), and rim joist gaps (right)

Phase I Aerosol Sealing Options 

The major goal of this project was to determine the best stage(s) of construction to apply aerosol 

envelope sealing and identify any current sealing methods that could be eliminated when aerosol 

sealing is used. Although there were some opportunities for the aerosol sealing method to 

produce tighter houses for this builder, it was expected that the greatest benefit would be a 

possible reduction in overall sealing costs by eliminating many of the current sealing practices. 

The identification of air sealing that might be eliminated was based on an understanding of how 

each building component was being sealed, whether the component air leaks would be accessible 

during the aerosol sealing process, and whether the leakage gaps would be small enough to be 

sealed by the aerosol process. It was assumed that the aerosol sealing would be performed at an 

early stage of construction, prior to the installation of drywall. Table 9 lists the 13 types of leaks 

that were judged to have current sealing methods that might be eliminated or significantly 

reduced by aerosol sealing. The leaks are grouped by the contractor that typically performs the 

manual sealing of the type of leak. Insulation contractors seal the greatest number of leak types 

(seven), but carpenters also seal four types and insulation/electrical contractors seal three. A 

complete description of the types of leaks is included in Appendix C. 
Aerosol Envelope Sealing of New Residences

51

Table 9. Current Air Sealing That Could Possibly Be Eliminated With Aerosol Sealing

Type of Leak Category Material Used for Sealing?

Carpentry Contractor

Shower/tub on exterior wall Other OSB/polyethylene sheet

Stair stringer on exterior wall Other Polyethylene sheet

Interior partition wall to exterior 

wall Walls Polyethylene sheet/caulk

Sill plate Walls Sill seal/caulk

Insulation Contractor

Top plate Walls Polyethylene sheet/caulk

Rough openings Windows, skylights and doors Can foam

Plumbing penetrations Shafts and penetrations to 

unconditioned spaces Can foam

Piping penetrations Shafts and penetrations to 

unconditioned spaces Can foam

Wiring penetrations Shafts and penetrations to 

unconditioned spaces Can foam

HVAC register boots that 

penetrate building thermal 

envelope

Other Can foam

Rim joists Rim joists Closed-cell spray foam

Insulation Contractor/Electrician

Electrical/low-voltage boxes on 

exterior walls Other Polyethylene sheet/caulk/gasketed boxes

Recessed lighting fixtures Ceiling/attic Polyethylene sheet/gasketed 

fixture

Electrical/low-voltage boxes on 

exterior walls Other Polyethylene sheet/caulk/gasketed boxes
Aerosol Envelope Sealing of New Residences

52

Project staff met with builder representatives to discuss when to apply the aerosol sealing and 

identify sealing methods that could be eliminated. The builder was hesitant to eliminate any of 

their sealing methods for the first set of houses, but indicated that they would consider changes 

for the next set of houses based on results from additional houses. Although the aerosol sealant

was shown to seal gaps at the rim joist, they were not comfortable with other options available to 

replace the insulating and vapor retarder functions of the spray foam. There was concern that the 

aerosol sealant would not satisfy fire code requirements being provided by can foam at the 

penetrations. They considered the poly sheeting on exterior walls to be a historically proven 

vapor retarder and were unsure whether code officials would allow them to replace the sheeting 

with low-perm paint on the drywall. 

The builder agreed to have the aerosol sealing performed after the following work was 

completed: (1) closed-cell spray foam applied to the rim joists and (2) can foam used to seal 

plumbing, piping, electrical, and other penetrations. The sealing was to be performed before 

three work items were performed: (1) wall insulation, (2) poly sheeting applied to the exterior 

walls, and (3) caulking of the framing joints. Fortunately, there were some variations in the 

aerosol envelope sealing applications for the first set of houses. Two of the four hours had wall 

insulation in place on the day of the sealing, and one house had almost no can foam sealing of 

electrical and plumbing penetrations to the attic.

Phase I Aerosol Sealing 

In the fall of 2017, four houses in the Twin Cities metropolitan area were aerosol sealed. The 

sealing profiles for the houses are shown in Figure 36. For the two houses with no wall insulation 

(#1310: blue and #14: green), the sealing proceeded fairly smoothly and was completed in about 

2 hours. The starting envelope leakages were 3.81 and 3.78 ACH50, respectively, and those were 

reduced by 72% and 82% to 1.05 and 0.67 ACH50 (Figure 37 and Table 10). The average postsealing leakage of 0.86 ACH50 was 71% below the code requirement of 3.0 ACH50 and 34% 

below the average leakage of 1.32 ACH50 for the eight control houses at the end of construction. 

When the sealing was stopped, it appeared that the rate of sealing had decreased significantly; 

the leakage was already 65% and 78% below the code-required leakage of 3.0 ACH50. A visual 

inspection showed that the gaps between the sheathing/top plate, sheathing/sill plate, sill 

plate/subfloor, and vertical framing were sealed (Figure 38). Although these gaps were typically 

narrow, there are hundreds of feet of these gaps in each house. This suggests that the total 

leakage area of those gaps could be significant and responsible for a majority of the leakage 

reduction. In addition, a tight air barrier was created at the exterior side of the wall cavities that 

produced low leakage levels of 1.05 and 0.67 ACH50. This eliminates the need for an interior air 

barrier11 that consists of a number of sealing components including poly sheeting and airtight 

electric boxes.

10 See Table 4 for information on house characteristics and stage of construction the sealing was performed. 11 This assumes that there are no significant driving forces from the house interior that would force interior house air 

to circulate through the wall cavities.
Aerosol Envelope Sealing of New Residences

53

Figure 36. Sealing profile for the first four houses in Minnesota Builder 3’s Phase I
Aerosol Envelope Sealing of New Residences

54

Table 10. Summary of Minnesota Builder 3 Sealing Results

House 

# 

Floor 

Area 

(ft2) 

Volume 

(ft3) 

Pre-Seal Post-Seal End of Construction

CFM50 ACH50 CFM50 ACH50

% 

Reduction CFM50 ACH50

Change 

(CFM50) 

12 3,338 33,518 2,200 3.94 358 0.64 84% 423** 0.76 65

13 4,361 41,504 2,637 3.81 728 1.05 72% 623 0.90 -105

14 3,913 36,469 2,300 3.78 409 0.67 82% 560 0.92 151

15+ 4,186 39,533 1,893 2.87 1,023 1.55 46% 541 0.82 -482

16+ 4,428 41,743 1,959 2.82 674 0.97 66% * * * 

17 3,972 35,955 1,690 2.82 279 0.47 83% 574 0.96 295

18 4,360 39,727 1,487 2.25 311 0.47 79% 719** 1.09 408

* The garage was converted to a sales office. It was not possible to test the house using the same 

configuration as that for the post-sealing test.

** Project staff did not conduct an end-of-construction test. The leakage is based on a HERS 

rater report. The house configuration for the test could not be confirmed to be the same as for the 

post-sealing test.

+ Wall insulation in place when the aerosol sealing started.
Aerosol Envelope Sealing of New Residences

55

Figure 37. Air leakage results for Minnesota Builder 3

Figure 38. Example aerosol seals: between framing (left); between sill plate/sheathing; between sill 

plate/subfloor

It was expected that the electric wire and plumbing penetrations from the house to the attic 

would be sealed with can foam. However, for House #13, the insulation contractor had not sealed 

the penetrations prior to the aerosol sealing. The penetrations were left unsealed to evaluate the 

effectiveness of aerosol sealing of the penetrations. A visual inspection with a smoke puffer was 

performed on the penetrations after the aerosol sealing. There were no noticeable gaps and no 

smoke movement at any of the penetrations. After the post-sealing air leakage test was 

completed, the penetrations were sealed with can foam and the leakage test repeated. The house 
Aerosol Envelope Sealing of New Residences

56

leakage decreased by only 15 CFM50. That indicates that the aerosol sealing effectively sealed 

electrical and plumbing penetrations to the attic.

Due to a miscommunication with the insulation contractor, batt insulation was installed in the 

exterior walls of houses #15 and #16 prior to the aerosol sealing. The smaller reductions in 

leakage for these two houses indicate that aerosol sealing should not be conducted when exposed 

batt insulation covers exterior sheathing. The results from these two houses are excluded from 

the summary results for the Minnesota houses. However, a description of the results is included 

in this section to document the impact of the wall insulation on the aerosol sealing effectiveness. 

For the first house (#15), the wall insulation was left in place for the start of the sealing. Figure 

39 shows a comparison of the sealing profiles for a house with wall insulation (#15) and without 

(#14). The wall insulation resulted in a much longer sealing time and lower sealing. The house 

without insulation started with a sealing rate of almost 50 CFM50/min (green solid line in Figure 

39) and slowly decreased to 5 CMF50/min after 90 minutes of sealing. In less than 2 hours the 

house leakage was reduced by 82%. In contrast, for the house with wall insulation, the sealing 

rate was never above 15 CFM50/min (red solid line) and averaged about 5 CFM50/min for the 

first 3 hours of sealing. Four hours of sealing only produced a leakage reduction of 46%. During 

the aerosol sealing it was observed that the gap around an electrical box installed in the drywall 

between the house and garage was not being sealed. Sealant started to form in the gap as soon as 

the batt insulation around the box was removed. For the last 1 to 2 hours of sealing, some of the 

insulation batts were pulled from the top of the cavities with the lower section of the batt left in 

place. This appeared to marginally improve the sealing rate for a short period of time.
Aerosol Envelope Sealing of New Residences

57

Figure 39. Sealing profile for House #14 (no wall insulation) and #15 (insulated)

For the second house with wall insulation (#16), many of the insulation batts were completely 

removed from the cavities and some were simply pulled down from the top with the bottoms left 

in place. As shown in Figure 36, the sealing rate for House #16 was better than that for the house 

with all batts in place (#15), but worse than the two with no wall insulation. For #16, the initial 

leakage of 2.82 ACH50 was reduced by 66% to 0.97 ACH50. This shows that batt insulation acts 

as a filter to the sealant for gaps at the exterior sheathing. This suggests that when aerosol sealing 

is performed before drywall is in place, a significant fraction of the aerosol sealing occurs 

between the sheathing and other construction. In addition, when aerosol sealing is performed 

after drywall and wall insulation is in place, aerosol sealant that is able to enter into the wall 

cavity will likely be filtered by the insulation and will not seal gaps at the sheathing. 

Although the aerosol sealing for House #13 was completed within 2 hours, there were minor 

issues that extended the time for the other three houses. The compressor pressure control 

malfunctioned, which resulted in additional time diagnosing the issue and limited the number of 

sprayers that could be used for the three houses. In addition, for two of the houses (#13 and #16) 

the poly sheet on the ceiling came loose from the framing, which caused a large air leakage 

(Figure 40). For House #16, the opening in the sheet is evident by an increase in the leakage at 

about 120 minutes (Figure 36). The sheets were caulked and stapled to the framing, but the 
Aerosol Envelope Sealing of New Residences

58

stapling process needed to be more robust to hold the sheets in place against the high sealing 

pressure of 100 Pa. 

Figure 40. Poly sheet pulled away from framing

Phase II Aerosol Sealing 

The project team met with builder representatives to review the sealing approach for the two 

Phase II houses. It was agreed that the time of construction for the aerosol sealing for the Phase I 

houses was successful and would not change. It would be performed after spray foam was 

applied to the rim joists, poly sheeting caulked/stapled in place on the second floor ceilings, and 

can foam used to seal electrical and other penetrations. The wall insulation and drywall would 

not be in place. It was agreed that more careful installation of the ceiling poly would be a point 

of emphasis with the insulation contractor and that the poly would be carefully inspected prior to 

the sealing. The builder and project team established a goal to achieve leakage less than the 

Passive House requirement of 0.6 ACH50. 

It was noted that the average leakage of 0.8 ACH50 for the three demo and Phase I houses 

without wall insulation was well below the 3.0 ACH50 code requirement and below the range of 

1.0 to 1.5 ACH50 typically achieved by the builder. Given the success of the Phase I sealing, the 

leakage goal for the Phase II houses was the Passive House standard of 0.6 ACH50. Because the 

leakage for the Phase I houses was achieved prior to application of the interior poly sheeting on 

the walls, the poly was not necessary to meet their leakage goals. The poly could be eliminated 

and the vapor retarder requirements met by low-perm paint (see discussion of air barrier and 

vapor retarder requirements in Appendix B). The builder tentatively agreed to not use poly and 

airtight electric boxes on the two Phase II houses as long as their construction managers and code 

officials agreed to this change. The necessity for interior poly sheeting on exterior walls has been 

a point of emphasis for Minnesota builders and code officials for many years. The construction 

managers were not comfortable with eliminating the poly, so it was used for both houses. 
Aerosol Envelope Sealing of New Residences

59

The aerosol envelope sealing of the two Phase II houses was extremely successful. The sealing 

profiles for the houses are shown in Figure 41. The rate of sealing started at about 25 CFM50/min 

for House #17 and 45 CFM50/min for #18. Similar to previous houses without wall insulation, 

the rate of sealing decreased slowly over time. The sealing was stopped after 95 and 105 minutes 

when the rate of sealing dropped below about 5 CFM50/min. There were no interruptions due to 

equipment malfunctions or issues with the ceiling poly. The starting envelope leakages were 2.82 

and 2.25 ACH50, and those were reduced by 83% and 79%, respectively. Both houses had a 

leakage of 0.47 ACH50 (Figure 41 and Table 10) after sealing, which was 84% below the code 

requirement of 3.0 ACH50 and 64% below the average leakage of 1.32 ACH50 for the eight 

control houses at the end of construction. Additionally, the average for the houses was 22% 

lower than the Passive House standard of 0.6 ACH50 and 77% below the DOE Zero Energy 

Ready standard of 2.0 ACH50 for climate zone 6 (DOE 2019). This was further documentation 

that aerosol envelope sealing applied prior to wall insulation and drywall can produce a very 

tight air barrier at the exterior side of the wall cavity.

The builder showed interest in a demonstration of aerosol envelope sealing under cold outdoor 

weather conditions to determine whether there would be any restrictions to the application during 

Minnesota winters. Due to scheduling constraints for the AeroBarrier contractor and houses, the 

houses were not sealed under extreme weather conditions. For both houses the overnight low 

temperature prior to sealing was 23°F, and the temperature during sealing was 30° to 35°F. The 

houses were kept warm with temporary furnaces prior to the sealing (common practice for this 

builder). There were no temperature-related issues for the sealing of the two houses. The houses 

were pre-heated for application of spray foam.12 The interior house temperature required for 

spray foam application was sufficient for effective aerosol sealing

12 During the heating season, Minnesota insulators typically use a closed-cell spray foam that can be applied at an 

ambient and substrate temperature down to 23°F.
Aerosol Envelope Sealing of New Residences

60

Figure 41. Sealing profile for two Phase II houses

End-of-Construction Leakage 

The house assessments and air leakage tests were repeated at the end of construction for six of 

the seven13 aerosol-sealed houses. The tests were performed to determine whether the houses 

became tighter or leakier through the rest of the construction process. It was possible that 

completion of the interior air barrier could cause the houses to be tighter. Houses could become 

leakier if there was inadequate sealing of any additional penetrations or seals created by the 

aerosol sealing were disturbed by the remaining construction. The measured leakages are 

included in Table 10 and represented by green bars in Figure 37. 

When evaluating the change in leakage from the post-aerosol test to the end-of-construction test, 

it is important to consider that it was necessary to temporarily seal numerous openings for the 

post-sealing test14 that were left open for the end-of-construction test. These may have included 

clothes dryer vents, bathroom exhaust fan ducts, kitchen exhaust fan ducts, heat recovery 

ventilator inlet/exhaust ducts, furnace vent pipes, and water heater vent pipes. In addition, the 

post-sealing test was conducted as a pressurization test, whereas the end-of-construction was 

13 House #16’s garage was converted to a sales office. It was not possible to test the house using the same 

configuration as the post-sealing test. 14 Such openings were sealed when there was not an appliance or backdraft damper in place that would be present at 

the end of construction.
Aerosol Envelope Sealing of New Residences

61

conducted as a depressurization test. In order to evaluate the impact of the different test 

procedures, at the end of construction, six of the Minnesota builder houses were tested with two 

different procedures: (1) pressurization with sealed openings—similar to the post-sealing test—

and (2) depressurization with unsealed openings. The increase in measured leakage using the 

unsealed procedure varied from -1 to 176 CFM50 and averaged 81 CFM50. This suggests that 

increases in leakage from the post-sealing to the end-of-construction up to 150–200 CFM50 could 

be due to the differences in the test procedure and not an increase in leakage. The results for the 

change in leakage from the post-sealing measurement were mixed. For four of the houses the 

change ranged from -105 to 295 CFM50 and averaged 102 CFM50 or 0.18 ACH50. The change 

was similar to the average difference in the test procedures (81 CFM50). This suggests little 

change in the leakage of the air barrier that was created by aerosol sealing or that any significant 

leakage increase in that barrier was offset by leakage reduction from completion of the interior 

air barrier. One house had an increase in leakage of 408 CFM50 or 0.62 ACH50. However, the 

reported leakage is based on a HERS rater measurement and the house setup could not be 

confirmed to be the same as for the post-sealing test. Some of the increase in leakage could have 

been a result of differences between the post-sealing and HERS rater’s house setup. 

Finally, the leakage for first house with exposed wall insulation (#15) decreased by 482 CFM50

or 0.73 ACH50. The house had wall insulation batts installed at the start of aerosol sealing and 

the post-sealing leakage was the highest of all sealed houses—1.55 ACH50. It appears that the 

interior air barrier installed after the aerosol sealing significantly reduced the house leakage. For 

the second house with exposed wall insulation (#16), the garage was converted to a sales office. 

The end-of-construction air leakage test could not be conducted for the same portion of the 

structure that was tested after the aerosol sealing was completed. 

Project staff conducted end-of-construction envelope leakage tests for three houses that did not 

have wall insulation in place for the aerosol sealing.15 Sealed houses ranged from 0.90 to 0.96 

ACH50 with an average of 0.93 ACH50. This average is 69% below the energy code requirement 

of 3.0 ACH50, 54% below the DOE Zero Energy Ready standard of 2.0 ACH50 for climate zone 

6, and 30% below the average end-of-construction leakage for the eight control houses. 

The leakage of exhaust fan inlets, heat recovery ventilator intakes/exhausts, and electric boxes 

was measured using a custom calibrated TEC Exhaust Fan Flow Meter with multiple 1-in. 

diameter holes. The exhaust fan inlet leakage varied from 5 to 18 CFM50. The leakage of the heat 

recovery ventilator intakes/exhausts was only 4 and 12 CFM50 for one unit, but much higher (42 

and 56 CFM50) for a second unit. There was no measurable leakage for any of the electric boxes 

tested. 

15 The end-of-construction tests were conducted by a HERS rater for Houses #12 and #18. Houses #15 and #16 had 

wall insulation in place at the start of the aerosol sealing.
Aerosol Envelope Sealing of New Residences

62

5.2.2 Second Minnesota Builder (#4)

The second builder was a midsize residential builder with multiple developments in the 

Minneapolis-St. Paul metropolitan area. Project staff had conducted field inspections of many of 

this builder’s homes and was familiar with the approaches to and quality of their air barrier 

sealing. That experience was used to generate the table of air sealing components included in 

Appendix C. The results were similar to those for the first Minnesota builder. Experience 

indicated an overall high quality of air sealing that was confirmed by the low envelope leakage 

of their recently completed houses. For example, the envelope leakage of four similar houses 

ranged from 0.86 to 1.97 ACH50. The average leakage of 1.36 ACH50 is 55% below the State of 

Minnesota code requirement of 3.0 ACH50. 

The aerosol envelope sealing demonstration was very successful. The house had drywall in 

place, and the construction was nearly complete with a low leakage of only 419 CFM50 (0.70 

ACH50) prior to sealing. As a result, the sealing rate over the first 30 minutes was only 5 and 10 

CFM50/min (Figure 42; House #19). The 40 minutes of sealing reduced the leakage by 50% to 

209 CFM50 or 0.35 ACH50. The low leakage at the start of sealing suggests that for this builder, 

the primary benefit of the aerosol sealing would likely be to reduce sealing costs by eliminating 

current sealing methods. 

Figure 42. Sealing profile for three houses for Minnesota Builder #4
Aerosol Envelope Sealing of New Residences

63

The project team met with builder representatives to review the results of the house assessments 

and demonstration sealing. It was agreed that the Phase I houses would be sealed at the same 

time of construction and the same preparation as that used for the first builder—post-rim/band 

joist sealing/prior to wall insulation and sheetrock. The goal was to meet or exceed the Passive 

House standard of 0.6 ACH50. The builder was hesitant to eliminate any of their sealing methods 

for the Phase I houses, however, but indicated that they would consider changes for Phase II 

houses based on results from the additional houses. 

5.2.3 Phase I Aerosol Sealing

The team expected that there would be two houses available to seal at the end of March 2018, 

but only one house was at the appropriate stage of construction when the AeroBarrier staff were 

in Minnesota to perform the work.16 The sealing for House #20 proceeded fairly smoothly and 

was completed in 70 minutes (Figure 42; #20, green). The sealing rate continued at about 25 

CFM50/min for about 20 minutes and dropped below 5 CFM50/min when the leakage was about 

350 CFM50. The starting envelope leakage was 1.91 ACH50 and was reduced by 78% to 0.42 

ACH50 (Figure 43 and Table 11). The post-sealing leakage was 86% below the code requirement 

of 3.0 ACH50, 77% below the DOE Zero Energy Ready standard of 2.0 ACH50, and 25% lower 

than the Passive House standard of 0.6 ACH50. Finally, it was 61% below the average leakage of 

1.06 ACH50 for the four control houses at the end of construction. Similar to the pre-drywall 

sealing for Minnesota Builder 4, visual inspection showed that the gaps between the 

sheathing/top plate, sheathing/sill plate, sill plate/subfloor, and vertical framing were sealed. This 

reinforced the observation that aerosol sealing before the application of drywall and insulation 

can eliminate the need for an interior air barrier for reducing air leakage through the envelope. 

Table 11. Summary of Minnesota Builder 4 Phase I Sealing Results

House #

Floor 

Area 

(ft2) 

Volume 

(ft3) 

Pre-Seal Post-Seal End of Construction

CFM50 ACH50 CFM50 ACH50

% 

Reduction CFM50 ACH50

Change 

(CFM50) 

19 4,135 35,916 419 0.70 209 0.35 50% 548 0.92 339

20 4,603 41,497 1,323 1.91 290 0.42 78% 429 0.62 139

21 3,698 33,358 2,270 4.08 407 0.73 82% 597 1.07 190

22 3,243 28,875 1,593 3.31 474 0.98 70% 519 1.08 45

16 A local AeroBarrier contractor was trained and became available to perform aerosol envelope sealing in August 

2018. This provided significantly more flexibility to schedule the remaining sealing work.
Aerosol Envelope Sealing of New Residences

64

Figure 43. Air leakage results for Minnesota Builder #4

5.2.4 Phase II Aerosol Sealing

The project team met with builder representatives to review the sealing approach for the two 

Phase II houses. They agreed that the timeline of the sealing approach used in Phase I had been 

successful, and elected to apply sealing at the same time of construction for Phase II. Similar to 

the timeline for the first Minnesota builder, it would be performed after spray foam was applied 

to the rim joists, poly sheeting was caulked and stapled in place on the second floor ceilings, and 

can foam was used to seal electrical and other penetrations. The wall insulation and drywall 

would not yet be in place. The builder and project teams aimed to achieve leakage below the 

Passive House requirement of 0.6 ACH50. 

The aerosol envelope sealing of the two Phase II houses was very successful. The sealing profile 

for House #2217 is shown in Figure 42. The rate of sealing started at only 10 CFM50/min, but 

increased to 25 CFM50/min after 20 minutes. The sealing rate slowly decreased to 5 CFM50/min 

after 65 minutes, when the house leakage had dropped to about 450 CFM50 or a little less than 

1.0 ACH50. The sealing was stopped shortly after that time. As noted previously, the stretch goal 

for these houses was to achieve an envelope leakage of 0.6 ACH50 or less. However, the sealing 

crew determined when the leakage had “bottomed out” and stopped the sealing at that point. 

While the rate of sealing is not computed and displayed for the crew, for the Minnesota houses 

the sealing was typically stopped when the rate of sealing dropped below about 5 CFM50/min.

17 The airflow rate data was not recorded properly for House #21 for most of the sealing process.
Aerosol Envelope Sealing of New Residences

65

There were no interruptions due to equipment malfunctions or issues with the ceiling poly. The 

starting envelope leakages were 4.08 and 3.31 ACH50, and those were reduced by 82% and 70%, 

respectively, with post-sealing leakages of 0.73 and 0.98 ACH50 (Figure 42 and Table 12). The 

leakages were 76% and 67% below the code requirement of 3.0 ACH50, and 31% and 7% below 

the average leakage of 1.06 ACH50 for the four control houses at end of construction. 

Additionally, the leakages were 63% and 51% below the DOE Zero Energy Ready standard of 

2.0 ACH50. This was further documentation that aerosol envelope sealing applied prior to wall 

insulation and drywall can produce a tight air barrier at the exterior side of the wall cavity. 

However, the sealing fell somewhat short of the stretch goal to achieve leakages less than 0.6 

ACH50. 

5.2.5 End-of-Construction Leakage

The house assessments and air leakage tests were repeated at the end of construction for four the 

houses that were aerosol sealed for Minnesota Builder 4. The tests were performed to determine 

whether the houses became tighter or leakier through the rest of the construction process. The 

measured leakages are included in Table 12 and represented by green bars in Figure 43. For three 

of the houses, there were moderate increases in leakage (45, 139, and 189 CFM50), which could 

be explained by the difference in the test procedure.18 This suggests little change in the leakage 

of the air barrier that was created by aerosol sealing or that any significant leakage increase in 

that barrier was offset by leakage reduction from completion of the interior air barrier. It is not 

clear why there would have been a 339 CFM50 (0.57 ACH50) increase in leakage for the 

demonstration house (#19). The house was sealed near the end of construction. A pressurization 

test with openings sealed was conducted pre-sealing (419 CFM50), post-sealing (209 CFM50), 

and at end of construction (448 CFM50). The house was tight prior to the sealing (0.70 ACH50), 

and the limited reduction of 210 CFM50 from the sealing was countered by added leakage from 

the time of aerosol sealing to the end of construction. The end-of-construction assessment did not 

identify any significant air leakage. 

5.2.6 Minnesota Builders 5–8 

The project team recruited four more Minnesota builders to evaluate sealing methods for: (1) a 

type of construction and (2) an air sealing approach that are used somewhat often in Minnesota 

but were not represented in the first two Minnesota builders’ houses. The additional houses used 

continuous exterior insulation, spray foam wall insulation, and a flat roof with slab-on-grade 

floor. Three of the houses selected are located in the Twin Cities metropolitan area (Minnesota 

Builders 5, 6, and 8) and the house for Minnesota Builder 7 is located in the Rochester area.

Minnesota Builder 5 is an affordable housing developer. The 2,592 ft2 house that was sealed is 

similar in construction to those for the two previous Minnesota builders, except that a portion of 

the labor is provided by volunteers and the rim joists were insulated and sealed with rigid 

insulation board cut to fit between the joists. In addition, this house provided another opportunity 

18 As noted in the description of the results for the first Minnesota builder, the differences in the post-sealing and 

end-of-construction test procedures could result in an increase in leakage of up to 150–200 CFM50. 
Aerosol Envelope Sealing of New Residences

66

to evaluate the effectiveness of post-drywall aerosol envelope sealing. As shown in Figure 44, 

the sealing rate started between 15 and 20 CFM50/min, but dropped to 5 CFM50/min after about 

10 minutes, and slowly decreased from that time until sealing was stopped after 85 minutes. A 

lower sealing rate of 5 CFM50/min shortly after sealing starts is consistent with the results for the 

other house that was sealed post-drywall (#12). The envelope leakage started at a relatively low 

level of 1.62 ACH50, and the sealing reduced that by 73% to 0.44 ACH50 (Table 12 and Figure 

45). That is 85% below the code requirement of 3.0 ACH50 and 27% below the Passive House 

standard of 0.6 ACH50. Four similar houses constructed by this builder had envelope leakage that 

varied from 1.04 to 1.63 ACH50, with an average of 1.29 ACH50. The aerosol-sealed house 

leakage was 66% less than the average for the builder’s houses that did not have aerosol sealing. 

All of the builder’s houses participated in a utility new home efficiency program with tiered 

incentives based on modeled space conditioning energy use. Additional modeling showed that if 

the four houses with conventional sealing would have had aerosol sealing that produced a 

leakage of 0.5 ACH50 or less, the builder would have received an additional $200 in utility new 

home efficiency program incentives for each house. A leakage of 0.5 ACH50 was not a target for 

this builder, but in the future it would be helpful to demonstrate to the builder that the additional 

leakage reduction would provide a greater utility program incentive. The work for this builder 

shows that aerosol envelope sealing can decrease leakage even for relatively tight houses by 

more than 70% and allow them to achieve Passive House leakage requirements.
Aerosol Envelope Sealing of New Residences

67

Figure 44. Sealing profile for Minnesota Builder 5 (House #23), 6 (#24), and 8 (#26)

Table 12. Summary of Sealing Results for Minnesota Builders 5–8 

House #

Floor 

Area 

(ft2) 

Volume 

(ft3) 

Pre-Seal Post-Seal End of Construction

CFM50 ACH50 CFM50 ACH50

% 

Reduction CFM50 ACH50

Change 

(CFM50) 

23 2,592 23,274 628 1.62 170 0.44 73% 374 0.96 204

24 2,074 19,896 1,137 3.43 292 0.88 74% 319 0.96 27

25 3,334 33,418 6,405 11.5 738 1.33 88% 392 0.70 -346

26 3,882 42,896 1,230 1.72 232 0.32 81% 547 0.77 315
Aerosol Envelope Sealing of New Residences

68

Figure 45. Air leakage results for Minnesota Builders 5–8 

Minnesota Builder 6 is a small residential builder who wanted their houses to be tighter than 1.0 

ACH50. The two-story, 2,074 ft2 house is slab-on-grade with a flat roof and 2”x6” stud walls. The 

walls have batt insulation in the cavities, 0.5-in. plywood sheathing, building paper with taped 

joints as the air barrier, and two layers of 1-in. rigid insulation. The house was designed for batt 

insulation in the 20-in. ceiling cavities and three layers of rigid insulation above the roof deck. 

When the house was aerosol sealed, the wall and ceiling batt insulation had not yet been installed 

and the electrical penetrations were not sealed. In addition, the roof membrane had not been 

adhered to the wood blocking at the top of the exterior walls. Rigid insulation needed to be 

installed and sealed between the living space and garage before the aerosol sealing was 

performed.

As shown in Figure 44 (#24), the sealing rate started at about 20 CFM50/min and slowly dropped 

to 5 CFM50/min after 60 to 75 minutes, except for a brief increase when some leakage was 

manually sealed at the 20-minute mark. Sealing continued for another half hour so that the house 

leakage would be at least 10% below the target leakage of 1.0 ACH50. During the sealing, 

aerosol sealant could be seen blowing out the area under the roofing membrane. After the sealing 

was completed, a visual inspection found that the aerosol sealant filled gaps between the roof 

deck and the band joist. The envelope leakage started at a relatively low level of 3.43 ACH50, 

and the sealing reduced that by 74% to 0.88 ACH50 (Table 12 and Figure 45). That is 71% below 

the code requirement of 3.0 ACH50. This shows that aerosol envelope sealing can produce slabon-grade houses with leakages of less than 1.0 ACH50. Two similar (e.g., control) houses 

constructed by this builder had envelope leakages of 0.94 and 1.29 ACH50 with an average of 
Aerosol Envelope Sealing of New Residences

69

1.12 ACH50. The aerosol-sealed house leakage was 21% less than the average for the control 

houses that were not sealed. 

This builder typically participated in a utility tiered new home efficiency program. If the 

leakages of the two control houses were reduced to 0.5 ACH50 or less, the builder’s incentives 

would have increased by $500 and $300, respectively. For the aerosol-sealed house, reducing the 

leakage from the code requirement of 3.0 ACH50 to 0.88 ACH50 increased the incentive by $500 

for a total of $3,500. Reducing the leakage to 0.5 ACH50 would have further increased the 

incentive by $500 to $4,000, and the 2020 update to the program would increase the incentive to 

$4,500. An added incentive of $500 to $1,000 could pay for a significant portion of the aerosol 

sealing work.

Minnesota Builder 7 is a small-volume builder who was starting to produce high-performance 

houses. The builder was planning to use spray foam on exterior walls and under the roof decking 

of the slanted attic roof for thermal insulation and to reduce the typical leakage of their houses. 

The envelope leakage averaged 1.37 ACH50 for three similar houses that they had recently 

constructed. The objective was to evaluate whether aerosol envelope sealing—along with batt 

insulation in the walls and blown-in insulation in the attic—could provide the desired house 

leakage and give the builder a more cost-effective insulation approach. The house was aerosolsealed prior to the application of spray foam insulation. Drywall or poly was installed on the 

second floor ceiling so that the house could be pressurized for aerosol sealing. Because it was 

expected that the spray foam would seal larger gaps in the envelope, more extensive can foam 

sealing was necessary than for the other project houses in Minnesota. However, the electrical 

wire penetrations were judged to be small enough to be sealed by the aerosol process. 

The sealing profile is shown in Figure 46 (#25). The rate of sealing started at a high level of 150 

CFM50/min, and then after 15 minutes decreased to between 40 and 60 CFM50/min for the next 

35 minutes. This higher level of sealing was due to the higher starting envelope leakage of 11.5 

ACH50. With the aerosol sealing process, it is expected that all of the envelope leaks will be 

sealed simultaneously and, as a result, leakier houses will have higher sealing rates. The duration 

of sealing should largely be determined by the width of the leaks to be sealed and not the number 

or total length of the leaks. Prior research has shown that the time required for sealing a leak is 

proportional to the square of the leak width (shortest dimension for a two-dimensional slot leak), 

and the total amount of leakage (length of the leak) does not impact sealing time (Carrie and 

Modera 1998). The total leakage, however, will impact sealant injection rates to maintain particle 

concentration in the building and appropriate application humidity. Another contributing factor is 

the house leakage goal and whether it is necessary to continue to seal leaks with wider gaps 

(which take longer to seal) in order to meet the leakage goal. 

After about 65 to 70 minutes, the sealing rate dropped below zero. The AeroBarrier crew 

investigated the source of the problem and found that there was a large leak past the poly on the 

ceiling of one of the bathrooms. In addition, a number of large leaks in the attic space were 

identified and sealed. The aerosol sealing then resumed. The 2 hours of aerosol sealing reduced 
Aerosol Envelope Sealing of New Residences

70

the house leakage by 88% down to 1.33 ACH50 (Table 12 and Figure 45). The level was 56% 

below code, but similar to the value achieved for the builder’s other houses. However, the 

leakage of 1.33 ACH50 was achieved without spray foam wall or attic insulation and incomplete 

preparation for the aerosol sealing. At the end of construction after the spray foam was applied, 

the house leakage was further reduced to 0.7 ACH50. It is likely that better preparation would 

have allowed the aerosol sealing to achieve the desired house leakage without the need for spray 

foam insulation. In addition, the interim airtightness testing provides the builder with valuable 

insight into whether leakage targets are on track to be met during an earlier stage of construction 

when certain sources of leakage are still accessible.

Figure 46. Sealing profile for Minnesota Builder #7 (House #25)

Minnesota Builder 8 is a high-performance house builder strongly interested in using aerosol 

envelope sealing for all of their houses. The house was sealed prior to the installation of wall 

insulation and drywall. As shown in Figure 47 (#26), the sealing rate started at 20 CFM50/min, 

but dropped below 10 CFM50/min after about 40 minutes and slowly decreased from that time 

until sealing was stopped after 90 minutes. 
Aerosol Envelope Sealing of New Residences

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Figure 47. Sealing profile for Minnesota Builder #8 house (#26)

The envelope leakage started at a low level of 1.72 ACH50, and the sealing reduced that by 81% 

to 0.32 ACH50 (Table 12 and Figure 45). That is 89% below the code requirement of 3.0 ACH50. 

Four similar houses constructed by this builder had envelope leakage that varied from 1.45 to 

2.04 ACH50, with an average of 1.72 ACH50. The aerosol-sealed house leakage was 81% less 

than the average for this builder’s houses that were not aerosol-sealed. This shows that aerosol 

sealing can produce extremely tight houses for this builder. If the four non-aerosol-sealed houses 

would have had a leakage of 0.5 ACH50, the builder would have received an additional $500 to 

$1,000 in utility new home efficiency program incentives. 

5.3 Illinois Triplex

A residence in Illinois was sealed to demonstrate the effectiveness of the aerosol envelope 

sealing process for a building type for which the builder historically had difficulty meeting an 

envelope leakage requirement. The builder was constructing a number of income-eligible, slabon-grade, two-story triplexes in the suburban Chicago area. There are two units on the first floor 

(#27 and #28) and one unit on the second floor (#29). There is a common entry at the lower 

level. The second floor unit has an entry door off the common space on the lower level. The 

second floor unit has a flat roof, and the portion of #28 that is not below the second floor unit has 

a flat roof. Spray foam was applied to the rim joists and flat roof to parapet wall intersections. R21 fiberglass batt insulation was used for wall insulation, R-49 continuous polyisocyanurate 

insulation used for roof insulation. A house wrap was used as the weather-resistive barrier. The 

builder’s target leakage was the State of Illinois’s code required envelope leakage of 5.0 ACH50
Aerosol Envelope Sealing of New Residences

72

with verification by an air leakage test. It was assumed that the leakage requirement would apply 

to the sum of the exterior and interior leakage or total leakage as measured by a 

compartmentalization-type leakage test. Achieving a total leakage of 5.0 ACH50 was needed to 

meet the ENERGY STAR certification requirements. Additionally, a number of Minnesota 

builders had provided informal feedback that it was more challenging to meet envelope leakage 

requirements for slab-on-grade residences compared to houses with conditioned basements that 

are included in the test volume and surface area. The leakage requirement is based on the total 

leakage of the house divided by the house volume. Poured concrete basements are typically tight. 

Consequently, the above grade portion of a house can be leakier than the target and produce a 

total house leakage less than target because the overall leakage will be less than the target when 

the above grade and basement sections are combined. A slab-on-grade house does not have a 

tight basement to help offset a leakier above grade section.

Due to scheduling requirements, the three units were aerosol sealed after wall insulation and 

drywall were in place. The drywall had not yet been taped. The units were sealed individually 

with the blower door installed in the opening to the hallway so that the unit was pressurized with 

respect to both the outdoor and adjacent units. That sealing configuration provided aerosol 

sealing to both the exterior portion of the envelope (e.g., exterior walls and ceilings) and the 

interior portion (e.g., walls and horizontal surfaces between units) for all three units. If all three 

units were sealed simultaneously, only the exterior portion of the envelope would have been 

sealed.

The sealing proceeded smoothly, and all three units achieved an envelope leakage below the 

code requirement. The sealing profiles for the three units are shown in Figure 48. The rate of 

sealing started at about 20 CFM50/min for #28; for the other two units the sealing rate started at 

about 10 to 15 CFM50/min. Although these rates are lower than for the houses that were sealed 

pre-drywall, the sealing rates are consistent with the two houses that were aerosol sealed postdrywall (demonstration #19 and #23). For the second floor unit, the sealing was conducted for 

about 75 minutes when the sealing rate dropped below 5 CFM50/min. The starting leakage was 

7.68 ACH50 and was reduced by 73% to 2.83 ACH50, which is 43% below the code requirement 

of 5.0 ACH50 (Figure 49 and Table 13). The leakage of the first floor east unit started at 7.68 

ACH50. The sealing rate dropped below 5 CFM50/min after only 15 minutes, but the sealing 

continued for 90 minutes to assure that the final leakage would be well below 5.0 ACH50 in case 

future construction caused the unit to become leakier. After aerosol sealing the leakage decreased 

by 54% to 3.52 ACH50, or 30% below the code requirement. The first floor west unit started with 

the highest sealing rate, but after about 20 to 30 minutes the rate was similar to that of the other 

two units. The sealing rate dropped below 5.0 CFM50/min after about 45 minutes, but the sealing 

continued for a little more than 2 hours to provide a leakage that would comfortably meet the 

code requirement. The leakage of the first floor west unit started at 8.55 ACH50 and decreased by 

52% to 4.07 ACH50, which is 19% below the code requirement. During sealing of the west and 

east first floor units, there was considerable aerosol haze in the joining unit. This indicated 

weaknesses in the quality of fire caulking or foaming between units. During sealing the second 
Aerosol Envelope Sealing of New Residences

73

floor unit, it was visible from the exterior of the building that aerosol penetrated the parapet wallto-roof intersection. Throughout the remainder of the aerosol sealing process for the second floor 

unit, the exterior visual of misting aerosol dissipated, indicating that the leakage points were 

sealed. The parapet walls were spray foamed. A possible explanation is that the spray foam 

delaminated from the wall assembly-to-roof intersection, or that a cavity was left void by 

accident, allowing aerosol to travel vertically out the top of the parapet wall. No further 

investigation was conducted to verify cause. 

Post-aerosol sealing visual inspections showed that the aerosol created seals in many of the same 

locations observed for the two other post-drywall sealed houses. That included gaps around 

electric boxes, ceiling exhaust fans, and other penetrations. There were seals between the drywall 

and the sill plate and at any gaps in the drywall. The concrete-floor-to-polyisocyanurate 

insulation joint displayed a thick bead, which picture-framed the perimeter of the west and east 

units along the exterior wall. The team expected that much of the leakage through the drywall 

gaps would have been sealed by the drywall finishing work. Smoke puffer and infrared 

investigations did not find any significant air leakage locations. There was some moderate air 

movement into the heating system ductwork, suggesting that there were duct leaks that provided 

a path for air to leave the unit through ceiling cavities. Although the leakage reductions of 52% 

to 73% were somewhat less than achieved for other project houses, the work demonstrated that 

aerosol envelope sealing could provide a straightforward method for achieving code-compliant 

envelope leakage for slab-on-grade residential units. Reaching compliant leakage levels had been 

a challenge for the builder, and they had been concerned that they would need to make 

significant changes to their air sealing practices. 
Aerosol Envelope Sealing of New Residences

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Figure 48. Sealing profile for Illinois Triplex

Table 13. Summary of Sealing Results for Illinois Triplex

House 

# 

Floor 

Area 

(ft2) 

Volume 

(ft3) 

Pre-Seal Post-Seal End of Construction

CFM50 ACH50 CFM50 ACH50

% 

Reduction CFM50 ACH50

Change 

(CFM50) 

Change 

(%)

27 778 9,130 1,169 7.68 535 3.52 54% 581 3.82 46 9%

28 778 9,130 1,301 8.55 620 4.07 52% 452 2.97 -168 -27%

29 1,282 11,791 2,088 10.63 557 2.83 73% 493 2.51 -64 -11%
Aerosol Envelope Sealing of New Residences

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Figure 49. Air leakage results for Illinois triplex

In addition to the compartmentalization tests of unit total leakage, guarded air leakage tests were 

conducted to measure the envelope leakage to the exterior. The exterior leakage was subtracted 

from the total to provide an estimate of interior leakage—which includes leakage to adjoining 

units and the small common area. Table 13 displays the pre- and post-sealing total, exterior, and 

interior leakages for the three units. On average the exterior leakage accounts for only a third of 

the total leakage, and the percentage of exterior leakage was consistent. The first floor east unit 

had the lowest percentage of exterior leakage (29%), and the second floor unit had the highest 

(35%). This suggests that an intermittently operated exhaust ventilation system would likely 

draw a significant fraction of air from adjoining units and the common area. 

The total, exterior, and interior envelope surface areas were computed and used to generate the 

surface-area-normalized leakages that are included in Table 13. This shows that the normalized 

leakage of the interior portion of the envelopes is much greater than that of the exterior. For the 

first floor west unit, the normalized interior leakage is more than 10 times greater than that of the 

exterior. This suggests that the builder needs to focus more attention on interior leakage in order 

to achieve a lower total leakage for the units. After aerosol sealing, the exterior leakages were 

reduced by 49%, 55%, and 69% for the second floor, first floor east, and first floor west units, 

respectively, with final leakages of 0.13, 0.08, and 0.05 CFM50/ft2

. The largest relative change in 

leakage occurred for the second floor interior leakage, which caused the normalized interior 

leakage to be equal to that of the exterior leakage (0.13 CFM50/ft2). The first floor west and east 

unit interior leakages were only reduced by 45% and 54%, respectively, for final normalized 

leakages that were still quite high (0.96 and 0.38 CFM50/ft2, respectively). Because visual and 
Aerosol Envelope Sealing of New Residences

76

smoke-puffer-aided inspections did not identify any significant interior leakage locations, this 

suggests that there could be diffuse leakage at the interior envelope surface that has large leakage 

pathways between the units. Further inspections at earlier stages of construction could help 

identify and address those pathways. 

Table 14. Detailed Illinois Triplex Leakage

House # Total Exterior Interior Total Exterior Interior Total Exterior Interior

Surface Area (ft2) Pre-Leakage (CFM50) Pre-Norm. Leakage 

(CFM50/ft2)

27 2,972 1,976 996 1,169 341 828 0.39 0.17 0.83

28 2,991 2,481 510 1,301 423 879 0.44 0.17 1.72

29 4,309 2,856 1,452 2,088 730 1,358 0.48 0.26 0.94

Post-Leakage (CFM50) Post-Norm. Leakage 

(CFM50/ft2)

27 535 154 381 0.18 0.08 0.38

28 620 133 487 0.21 0.05 0.96

29 557 374 183 0.13 0.13 0.13

Leakage Reduction (CFM50) Leakage Reduction (%)

27 634 187 447 54% 55% 54%

28 681 290 392 52% 69% 45%

29 1,531 356 1,175 73% 49% 87%

End Construction Leakage 

(CFM50)

End Norm. Leakage 

(CFM50/ft2)

27 581 326 255 0.20 0.16 0.26

28 452 230 222 0.15 0.09 0.44

29 493 365 128 0.11 0.13 0.09

Leakage Change (CFM50) Leakage Change (%)

27 46 172 -126 9% 112% -33%

28 -168 97 -265 -27% 73% -54%

29 -64 -9 -55 -11% -2% -30%
Aerosol Envelope Sealing of New Residences

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5.3.1 End-of-Construction Leakage

End-of-construction leakage was measured to determine whether the aerosol-sealed triplex units 

became tighter or leakier through the rest of the construction process. It was possible that 

completion of the interior air barrier could cause the houses to be tighter. Pouring gypsum 

concrete on the floor of the second floor unit would have likely had the most significant impact 

on reducing leakage between the units. However, the units could become leakier if there was 

inadequate sealing of any additional penetrations or seals created by the aerosol sealing were 

disturbed by the remaining construction. The total (i.e., sum of interior and exterior) leakages are 

included in Table 13 and represented by green bars in Figure 49. The total leakages ranged from 

2.51 to 3.82 ACH50 for units 29 and 27, respectively, and averaged 3.10 ACH50. For all of the 

units the total leakages were at least 24% below the Illinois code requirement of 5.0 ACH50, and 

the average leakage was 38% below the requirement.

The change in the total leakages for units #28 and #29 were only 46 CFM50 (9%) and -64 CFM50 

(-11%19), respectively. There was a large reduction of 168 CFM50 (27%) for one of the first floor 

units (#27). In general, the changes in total leakage were due to a moderate increase in exterior 

leakage and significant reduction in interior leakage. Table 14 includes the interior and exterior 

leakages that sum to the total. The upper unit (#29) had a small reduction of exterior leakage 

(9 CFM50 or 2%) and moderate reduction of interior leakage (55 CFM50 or 30%). The exterior 

leakage of the two first floor units (#27 and #28) increased by 97 CFM50 (73%) and 172 CFM50

(122%), respectively, while the interior leakage decreased by 265 CFM50 (54%) and 126 CFM50

(33%), respectively. This suggests that the work that occurred after the aerosol sealing tended to 

increase the exterior leakage somewhat but reduce the interior leakage significantly. Because the 

house setup was the same for the post-aerosol sealing and end-of-construction tests, it is likely 

that the 97 and 172 CFM50 increases in exterior leakage were caused by additional leaks caused 

by the remaining construction work. Conversely, the additional construction work resulted in an 

average reduction of interior leakage of 149 CFM50 (42%).

The leakage of units of an identical triplex constructed by the same builder and not aerosol 

sealed were measured to compare the impact of the aerosol sealing to standard construction. The 

total leakages ranged from 2.71 to 4.83 ACH50 and averaged 3.98 ACH50. The average leakage 

for the aerosol units was 22% less than that for the standard construction units. The sum of the 

exterior leakage for the aerosol-sealed units was 5% less than the value for the standard 

construction units, while the sum of the interior leakage was 37% less. This suggests that that 

aerosol sealing had a greater impact on reducing leakage between units than on exterior leakage, 

but this is too small of a sample to draw general conclusions. 

19 The uncertainties of the change in total leakage were less than 10 CFM50 for all three units. The uncertainties of 

the change in exterior and interior leakages are expected to be greater because the uncertainties of guarded test 

leakages are impacted not only by measurement errors but also the validity of the assumption that the units can be 

treated as discrete zones.
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5.4 Builder Interviews

Project staff conducted interviews with builders using 12 open-ended questions to initiate an 

informal discussion. The script, questions, and a summary of the feedback are included in this 

section.

1. What is the range of leakage that you typically get for your houses and what is the most 

typical leakage? Do you have a target leakage? What would be the biggest challenges in 

using aerosol sealing for your houses? 

The typical and target leakage rates for each builder are shown in Figure 50. The Minnesota 

builders all achieved ACH50 values under the climate zone 6 ceiling of 3.0—averaging between 

1.0 and 1.5—and set their targets near or below 1.0 ACH50. These builders view aerosol sealing 

as a good tool to help them lower their achieved values. The developers in California do not set 

ACH50 targets for themselves, nor do they conduct blower door testing of their homes, citing the 

lack of requirements in the California Building Energy Efficiency Standards and the relatively 

low performance credits achieved when meeting a lower leakage target. An ACH50 of 5.0 is 

regarded as standard in their area, and the developers assumed that by following local building 

codes they are achieving that standard. The midsize builder in California saw significant 

variation in the ACH50 values of their homes, ranging from about 2.0 to 5.0, but was uncertain of 

the cause.
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Figure 50. Builder-reported target (top) and typical (bottom) leakage rates

The most frequently stated challenge to using aerosol sealing was the cost and the difficulty 

justifying it to the builders’ customers (Figure 50). Customers are commonly less concerned with 

air sealing than with more visible and tangible aspects of their home, and are often willing to 

reduce overall costs by minimizing their investment in high-quality air sealing. If aerosol sealing 

enables them to eliminate other sealing measures (especially spray foam), this challenge will be 

greatly reduced.
Aerosol Envelope Sealing of New Residences

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Figure 51. Biggest challenge to using aerosol sealing

The developers in California, where the moderate climate makes air sealing a less pressing 

concern, expressed expectations that more builders may come to rely on aerosol sealing as 

regulations become increasingly stringent. This in turn would help the technology achieve 

greater scale and reduced costs to customers.

The other challenge that the builders shared was difficulty in scheduling the aerosol sealing, the 

most burdensome aspect being the need to empty the house of other workers. Again, builders 

expect that this issue would be largely mitigated by sufficient scaling of the product because the 

availability of local applicators would reduce scheduling complications.

The large residential builder in Minnesota voiced significant doubts as to whether moisture 

intrusion could be prevented in homes any tighter than their current standards. They already deal 

with a great deal of warranty issues that involve moisture intrusion, and they are fearful of the 

costs that would be incurred if such problems worsen due to reduced breathability as well as the 

challenge of balancing interior and exterior pressures in tightly sealed buildings. A major factor 

they cited was the challenge of ensuring that customers maintain their ventilation systems, which 

are especially crucial to maintaining the pressure balance in very airtight homes. 

2. What would be the most significant benefits in using aerosol sealing for your houses? 

The builders listed nine significant benefits for using aerosol sealing (Table 15). Many of the 

responses focused on reduced energy use. The most frequent responses were energy efficiency or 

reduced air leakage (three builders) and energy cost savings (two). Other cost benefits noted 

were utility incentives/credits (two builders), reduced rooftop solar costs in net zero energy 

homes (one), and saving subcontractor time (one). Non-energy and cost benefits included 

eliminating human error (two), improved air quality (one), and improved long-term durability 

(one).
Aerosol Envelope Sealing of New Residences

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Table 15. Benefits of Using Aerosol Sealing

Most Significant Benefits in Using 

AeroBarrier

Energy efficiency/reducing leakageEliminating human errorEnergy cost savingsUtility incentives/creditsAir 

quality

Passive House certificationReduc. rooftop solar $ in net zero homesLong-term home durabilitySaving subcontractors' time

CA Large Developer X 

CA Midsize Residential Builder X X 

MN High-Performance Custom Home 

Builder X X 

MN Large Affordable Home 

Developer X X X X 

MN Large Residential Builder X X X X 

MN Midsize Residential Builder

MN Small Residential Builder X 

3. At what point of the construction process would it make most sense for you to use aerosol 

sealing?

Almost all builders surveyed suggested applying AeroBarrier after rough inspection, prior to 

applying insulation. One builder suggested manually sealing visible gaps as usual prior to 

application and using aerosol sealing as a backup to seal undetectable leaks. The builders sought 

to achieve a fully sealed envelope before applying insulation and commented that this is also a 

convenient time to keep the house clear of other workers for the application. 

The only builder without a decisive stance spoke to the tradeoffs of applying aerosol sealing 

before and after insulation—application prior to insulation requires much more contractor 

coordination but makes it easier to confidently eliminate other air sealing measures. Aerosol 

sealing after drywall makes coordination much simpler, but any leaks it reveals within the wall 

cavity that must be sealed manually would require removal of the drywall. 
Aerosol Envelope Sealing of New Residences

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4. What current air sealing do you think you could eliminate if you were using aerosol 

sealing?

Almost half of the builders indicated that they would not eliminate any current sealing or were 

unsure what could be eliminated (Figure 52). The high-performance custom home builder and 

the small residential builder in Minnesota both stated that they would ideally incorporate aerosol 

sealing into their existing practices without eliminating other measures. However, the highperformance builder expressed interest in experimenting with future homes to determine whether 

other measures could be eliminated without compromising tightness—the small residential 

builder presumed that this would be possible, but said they preferred using aerosol sealing to 

increase redundancy in the building envelope. The midsize residential builder in Minnesota was 

likewise hesitant to eliminate alternatives, but would do so if aerosol sealing alone were proven 

effective. The California developer stated that “if the goal was to make the home as tight as 

possible, this product would be far superior to the method we used [when that was one of our 

goals],” citing far greater cost-effectiveness for comparable results. The Minnesota large 

residential builder was confident that polyethylene sheeting could be eliminated. 

Figure 52. Current sealing that could be eliminated

5. We are interested in the possible cost savings for eliminating some of these current 

sealing methods. Is it possible for you to make an estimate of the cost savings? If so, 

could you provide that to us? 

The Minnesota builders were not confident that eliminating other sealing methods by using 

aerosol sealing would provide significant savings. The California builders, however, suggested 

that it might be possible to calculate such savings and that insulation contractors would be the 

best source for reasonable estimates.

6. Are there certain types of houses or construction where you think aerosol sealing will be 

a better application?

Many builders surveyed agreed that aerosol sealing is a good solution for homes with 

complicated architecture or framing, which can make access to leaks challenging or impossible 
Aerosol Envelope Sealing of New Residences

83

(Figure 53). Two builders recommended the application for slab-on-grade homes, and another 

recommended it for what they considered the “ends of the spectrum” in terms of insulation 

investment: those with batt insulation at the low end, those with spray foam at the other. Another 

suggested applying aerosol sealing in their rambler homes, where large attic volumes make 

effective sealing difficult.

Figure 53. Best type of construction for aerosol sealing

7. Are there other housing types or parts of the country where you think aerosol sealing will 

have more impact?

All respondents stated that extreme hot or cold climates would likely see the greatest impact 

from using aerosol sealing, with one Minnesota builder suggesting that their state, specifically, 

would benefit most from the application. 

8. What would it take for you to incorporate aerosol sealing into your construction process? 

The main challenge that the builders expressed was the high cost of the application and their 

difficulty justifying its use to their customers. Most suggested that reducing this barrier would be 

the surest way to enable its incorporation into their regular operations. Two builders suggested 

developing a better sales strategy with which to approach their customers; two expressed a need 

for a nearby applicator to make scheduling more feasible and costs more attainable; and another 

suggested that finding the best point in the construction process to apply aerosol sealing would 

be helpful for scheduling purposes and to maximize its effectiveness. The Minnesota highperformance custom home builder said that the discount they received from their supplier had a 

large impact in enabling their use of the product, and both the large California developer and the 

midsize Minnesota residential builder suggested that building code changes could have a 

significant impact on cost-effectiveness. Increased air sealing requirements, they said, would 

force builders to implement solutions like aerosol sealing, enabling them to incorporate it into 

their construction process by reducing cost and increasing availability. Increased utility rebates 

would likewise improve cost-effectiveness, especially if builders could accurately model the 

tightness and resulting rebates achievable, as suggested by the midsize residential builder in 
Aerosol Envelope Sealing of New Residences

84

California. The same builder also suggested that more accurate home energy use modeling 

technology would improve their ability to evaluate the cost-effectiveness of aerosol sealing by 

providing a better comparison of its performance relative to other efficiency measures.

The large residential builder in Minnesota expressed more concern over moisture intrusion than 

anything else, and suggested they would need to change their building practices if they were to 

increase the tightness of their homes without increasing moisture intrusion. 

9. Do you currently use energy efficient homes and/or insulation and air sealing as a 

marketing tool? Now that you have witnessed the process and effectiveness of aerosol 

sealing, could you use it as a future marketing tool? 

Three of the five Minnesota builders surveyed use the energy efficiency of their homes as a 

marketing tool, proudly advertising their achievements in a climate that demands significant 

heating and cooling (Figure 54). The affordable housing developer is likely to increase their 

incorporation of energy efficiency in marketing materials for donors, who are more likely to be 

concerned with energy use than their clients for whom affordability generally supersedes other 

concerns. Similarly, the Minnesota midsize builder suggested that it would be easy to market 

aerosol sealing to clients particularly concerned about energy efficiency and home tightness. 

Figure 54. Energy-efficient home marketing

The large California developer does not market the energy efficiency of their homes, nor do they 

set additional efficiency or leakage targets in addition to state requirements. The midsize 

California residential builder, however, uses a carefully crafted marketing approach to sell their 

net zero energy homes. They voiced a need to educate their customers about the various factors 

that impact a home’s energy use, and the challenge of doing so. Air sealing could be used in their 

marketing, they said, but it is very difficult to demonstrate to the customer the benefit of paying 

more for aerosol sealing, as the results can easily go unnoticed. 
Aerosol Envelope Sealing of New Residences

85

10. What information or sales material would be beneficial to show home buyers the benefits 

of aerosol sealing? 

Three builders suggested providing a cost-benefit analysis of using aerosol sealing in the home to 

address buyers’ main concern (cost) with the product (Figure 55). The high-performance custom 

home builder also recommended showing the health benefits of the interior environment created 

in a well-sealed home. Materials recommended included brochures for display at open houses 

and other events and a video depicting the application procedure. Only the large residential 

builder in Minnesota was uninterested in marketing materials, as their customers do not seem to 

know enough about air sealing to concern themselves with it.

Figure 55. Beneficial information for home buyers

11. Compared to other builders, are you currently using home comfort as a talking point with 

potential home buyers and/or energy cost savings as an advantage with your homes over 

other builders? 

The Minnesota high-performance custom home builder and the California midsize builder were 

alone among those surveyed in using home comfort or energy cost savings as advantages of their 

homes when talking with potential home buyers (Figure 56). The California builder spoke to the 

difficulty of using energy cost savings as a talking point due to the small amount of savings that 

their customers gain. The Minnesota small residential builder plans to in the future though they 

currently do not, and the Minnesota affordable housing developer stated that comfort is of little 

concern to their customers relative to affordability. The Minnesota midsize builder, while not 

marketing the comfort of their homes as an advantage over other builders, has implemented 

various comfort-related practices—such as whole-home spray foam applications and dual-zone 

climate control—and speaks to that experience when clients raise questions about home comfort. 
Aerosol Envelope Sealing of New Residences

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Figure 56. Use home comfort and/or energy efficiency as talking point with potential homeowners

12. Do you typically receive utility energy efficiency incentives for your houses? If so, do 

you think that consistently getting your houses to 0.5 to 1.0 ACH50 with aerosol sealing 

would get you a higher incentive and, if so, how much more? If not, would you be more 

likely to pursue getting incentives if you were using aerosol sealing? 

All the builders were aware of, and made use of, utility energy efficiency incentives, but only the 

large residential builder in Minnesota found them lucrative enough to encourage lowering their 

ACH50 targets. The large developer in California expressed that the incentives were a bonus but 

not a deciding factor when building for high performance. The midsize builder in California 

expressed that the performance credits and incentives do not justify the cost to seal and verify the 

homes. 

5.5 Energy Modeling

Energy modeling was conducted to evaluate the impact envelope sealing has on home energy 

use. The simulations were conducted in each of the IECC climate zones to determine how 

climate conditions impact the results. Air sealing typically reduces the thermal loads on a 

building by reducing the amount of unconditioned air that enters buildings through leaks. 

In order to model a building using common energy simulation software, several assumptions 

must be made about the construction of the building and the performance characteristics of many 

of the systems within the building. The value of the results obtained from such a simulation is 

highly dependent on the specific capabilities of the modeling software and the extent to which 

the software allows dependent and independent variables to be analyzed. The independent 

variables include the building’s physical characteristics and operating parameters of the 

ventilation systems. The dependent variables include building energy use, total outside airflow 

(e.g., infiltration and ventilation), and interzonal airflows (e.g., adjoining units and units to/from 

common spaces). Clearly, the accuracy or validity of the various inputs and assumptions has 

significant influence on the results. 

Building Energy Optimization ToolTM (BEopt) was used to model energy savings when sealing 

homes to different leakage levels in several climate zones. BEopt is a parametric analysis tool 
Aerosol Envelope Sealing of New Residences

87

that allows multiple building configurations to be compared using EnergyPlus® as the simulation 

engine. The Building America B10 Benchmark (Hendron and Engebrecht 2010) was used for the 

baseline, and the envelope leakage was varied between 0.6 and 10.0 ACH50. The B10 

Benchmark is consistent with the 2009 International Energy Conservation Code (IECC 2009) 

and uses ASHRAE 62.2-2010 mechanical ventilation rates (ASHRAE 2010) and an envelope 

leakage of 7.0 ACH50. BEopt calculates the hourly infiltration rate based on both mechanical and 

natural forces. The mechanical system flows and natural (wind and stack) flows are combined to 

calculate the overall infiltration. Mechanical systems include bathroom and kitchen exhaust, and 

laundry dryers, which are scheduled to operate intermittently. Several IECC climate zones were 

modeled, including 1A, 2A, 2B, 3A, 3B-CA, 3B-Other, 3C, 4A, 4B, 4C, 5A, 5B, 6A, 6B, 7, and 

8. 

The model selected was a two-story, slab-on-grade, four-bedroom, three-bathroom, 2,400 ft2

home with an attached garage. The ceilings were 8 ft, and the B10 Benchmark values were 

selected for all fields other than the infiltration rate, which was the dependent variable analyzed. 

A gas furnace with a 78% annual fuel utilization efficiency was selected for heating, and a single 

package air conditioner with a seasonal energy efficiency ratio of 13 was selected for cooling. 

The space heating and cooling used a central distribution system located entirely in an unfinished 

attic with a total leakage of 15% of the total air handler flow. The clothes dryer, bathroom 

exhaust fans, and kitchen exhaust fan were scheduled to operate for an hour each day. There is a 

50-cfm exhaust fan in each bathroom that operates between 7 a.m. and 8 a.m. The 100-cfm 

kitchen exhaust fan operates between 6 p.m. and 7 p.m. The clothes dryer has an exhaust air flow 

rate of 100 cfm and is scheduled to operate for an hour each day between 11 a.m. and 12 p.m. 

The continuous mechanical ventilation system is an exhaust-only system that operates based on 

ASHRAE 62.2-2010 rates. 
Aerosol Envelope Sealing of New Residences

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Figure 57. Geometry of home used for infiltration modeling

5.5.1 Energy Savings

In order for builders to evaluate the benefit of producing tighter building envelopes, it is 

necessary to understand the energy savings associated with sealing their homes. There is a lack 

of data showing measured energy savings for homes that are sealed versus unsealed. In many 

cases the impact is too small to measure with the appropriate accuracy. Thus, building energy 

simulations are used evaluate the relative impact of air sealing for different climate zones in the 

United States. 

A BEopt analysis was performed to evaluate the impact of envelope air leakage on house energy 

use. Figure 58 shows a chart of the source energy savings for various levels of sealing for 16 

U.S. locations across 16 climate zones. The results show that reducing the leakage of a 2,400 ft2

single-family home from the B10 Benchmark of 7.0 ACH50 to 2.0 ACH50 would save 1%–18% 

of the source energy use for a home, depending on the climate zone. Sealing a home from 5.0 

ACH50 to 2.0 ACH50 would achieve 1%–11% savings, and sealing a home from 3.0 ACH50 to 0.6 

ACH50 would achieve 0%–6% source energy savings. Colder climates benefited the most from 

air sealing, with climate zones 5A, 6A, 7, and 8 showing the largest savings. 
Aerosol Envelope Sealing of New Residences

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Figure 58. Total energy savings from reducing air leakage in the model home in each U.S. climate zone

Figure 59 and Figure 60 present the cooling and heating source energy savings when reducing 

envelope leakage of homes in each of the 16 climate zones. The majority of the energy savings 

from sealing homes was due to reduced heating energy use. All climate zones had a reduction of 

at least 20% of source heating energy when sealing from 7.0 ACH50 to 2.0 ACH50. Multiple 

climate zones showed an increase in source energy used for cooling. This is a result of increased 

infiltration during periods when the air outside is cooler than inside providing “free cooling” to 

the homes. This occurred even with window some operation considered in the simulation, 

allowing windows to be opened when temperatures are cooler outside than inside. Many of the 

climate zones that showed an increase in cooling energy use were in cold climates that do not 

have significant cooling loads, so the results need to be considered relative to the reduction in 

heating energy use. 

Figure 61 and Figure 62 show the site energy use intensity for electricity and natural gas in each 

of the 16 climate zones. The total energy use intensity for both electricity and gas were lower 

with a tighter envelope in all climate zones except one. Climate zone 3B-CA (Los Angeles) 

showed a slight increase (0.5% or less) in electricity energy use due to the reduced infiltration. 

Reduction in ACH50
Aerosol Envelope Sealing of New Residences

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Figure 59. Cooling energy savings from reducing air leakage in the model home in each U.S. climate zone

Figure 60. Heating energy savings from reducing air leakage in the model home in each U.S. climate zone

-20%

-15%

-10%

-5%

0%

5%

10%

Cooling Energy Savings

7ACH50 to 2ACH50 5ACH50 to 2 ACH50 3ACH50 to 0.6ACH50

Reduction in ACH50

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

Heating Energy Savings

7ACH50 to 2ACH50 5ACH50 to 2ACH50 3ACH50 to 0.6ACH50

Reduction in ACH50
Aerosol Envelope Sealing of New Residences

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Figure 61. Cooling energy intensity reduction from reducing air leakage in the model home in each U.S. 

climate zone

Figure 62. Heating energy intensity reduction from reducing air leakage in the model home in each U.S. 

climate zone

-0.050

0.000

0.050

0.100

0.150

0.200

Electricity Savings (kWh/ft2/yr)

7ACH50 to 2ACH50 5ACH50 to 2 ACH50 3ACH50 to 0.6ACH50

Reduction in ACH50

0.000

0.050

0.100

0.150

0.200

0.250

0.300

Natural Gas Savings (Therms/ft2/yr)

7ACH50 to 2ACH50 5ACH50 to 2ACH50 3ACH50 to 0.6ACH50

Reduction in ACH50
Aerosol Envelope Sealing of New Residences

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6 Conclusions and Recommendations

Aerosol envelope sealing was very effective at sealing air leaks in the homes. Many of the 

demonstrations resulted in a tightness below 1.0 ACH50, which is well below the California 

prescriptive target of 5.0 ACH50 and Minnesota Energy Code requirement of 3.0 ACH50. The 

low air leakage was often achieved prior to completion of the homes, and in many cases prior to 

drywall being installed. This project demonstrated the ability to seal homes at various stages of 

construction, including before and after drywall is installed, allowing the process to be applied in 

a multitude of situations.

For the homes in California with unvented attics, the aerosol sealing was effective when applied 

before or after the spray foam insulation. Houses sealed after the spray foam was applied to the 

roof deck were quicker to seal and required less preparation than houses sealed before the spray 

foam was applied. The homes sealed before spray foam was applied demonstrated that aerosol 

sealing provided better air sealing results than open-cell spray foam insulation, allowing the 

builder to potentially use less expensive alternatives to insulate homes that are sealed with the 

aerosol technology. It will depend on the overall cost savings of alternative insulation methods to 

ultimately decide which option should be pursued in the future. The aerosol-sealed homes with 

unvented attics and open-cell spray foam ended up 39% tighter than the two control homes, with 

an average leakage of 1.1 ACH50 compared to 1.8 ACH50 for the controls. The two houses sealed 

with aerosols that used netted insulation had higher leakage rates than the homes with open-cell 

foam, averaging 2.6 ACH50 at the end of construction. The aerosol-sealed homes with the netted 

cellulose insulation were about 50% tighter on average than the three control homes, which had 

an average leakage of 5.1 ACH50. 

The average post-sealing leakage for the five California homes with vented attics was 1.71 

ACH50, which is 66% below the California nominal target of 5.0 ACH50 and slightly tighter than 

the sealed-attic houses without aerosol sealing. There was a significant increase in leakage after 

the end of aerosol sealing that can be largely attributed to leakage through fire sprinklers and 

backdraft dampers that were taped over during the aerosol sealing process. End-of-construction 

tests showed the aerosol-sealed homes were 33% tighter than the control homes. The aerosolsealed homes ended up at 3.1 ACH50 compared to the baseline homes at 4.6 ACH50. 

The seven houses sealed for the first Minnesota builder had an average air leakage of 0.98 

ACH50 after sealing and before the polyethylene sheet and drywall was installed—that is 50% 

tighter than the average leakage of the two control houses at the end of construction. This 

indicates that the required house tightness can be achieved without the interior poly, with the 

application of a low-perm paint satisfying the vapor barrier code requirement. Eliminating the 

poly sheeting and airtight electrical boxes, along with increased utility incentives, will help offset 

the added cost of the aerosol sealing. Field experience showed that for early construction sealing, 

greater care is required to adequately secure the ceiling poly sheets, and wall batt insulation 

should not be present. There may be added cost for the greater care and if installing the poly 

prior to the wall insulation requires an added trip. Another option is to install sheet rock on the 
Aerosol Envelope Sealing of New Residences

93

ceiling prior to the sealing. For the eight houses sealed for the other five builders, the sealing 

produced an average leakage reduction of 75% for an average post-sealing leakage of 0.68 

ACH50. Half of the houses had a leakage less than 0.6 ACH50, and only one house had a leakage 

greater than 1.0 ACH50. 

Post-aerosol sealing air leakage tests were repeated at the end of construction to determine 

whether the houses became tighter or leakier through the rest of the construction process. The 

assessment of the change in house leakage was complicated by differences in the house setup 

and test method. The post-sealing test was conducted as a pressurization test shortly after the 

aerosol sealing was complete when intentional openings were temporarily sealed, while most of 

the openings were left open for the end-of-construction depressurization test. All four California 

vented attic homes had significant increases in leakage from the post-sealing test to the end-ofconstruction test that ranged from 86 to 640 CFM50 and averaged 397 CFM50. Much of that was 

due to fire sprinklers (about 100 CFM50), and 200 to 300 CFM50 was through poorly fitting 

backdraft dampers. Fire sprinkler penetrations are within the envelope of sealed attic houses. The 

two sealed attic houses that were sealed after spray foam had only small (50 and 80 CFM50) 

increases in leakage. The two houses that were foamed after aerosol sealing had changes in 

leakage of -98 and 6 CFM50 from post-foam sealing to end of construction. 

In order to evaluate the impact of the different test procedures, at the end of construction, six of 

the Minnesota builder houses were tested with two different procedures: (1) pressurization with 

sealed openings (similar to the post-sealing test), and (2) depressurization with unsealed 

openings. The increase in measured leakage using the unsealed procedure varied from -1 to 176 

CFM50 and averaged 81 CFM50. Exhaust fan inlet leakage varied from 5 to 18 CFM50. The 

leakage of the heat recovery ventilator intakes/exhausts was only 4 and 12 CFM50 for one unit, 

but much higher (42 and 56 CFM50) for a second unit. Leakage through 25-ft long 6-in. flex 

combustion air ducts was about 100 CFM50. For all except one of the Minnesota and Illinois 

residences, there was either a decrease in leakage from the post-sealing to the end-ofconstruction tests or the increase was less than 205 CFM50. Five of the 16 had a decrease in 

leakage, with a maximum decrease of 482 CFM50 and average of 233 CFM50. For the other 11 

residences, 10 had an increase from 3 to 204 CFM50, and the average increase was 107 CFM50. 

This suggests that after the aerosol sealing there is little change in the house leakage through the 

rest of the construction process or that any impact on aerosol seals is offset by other sealing 

work. 

The Minnesota builders who participated in the study viewed aerosol sealing as a good option for 

improving energy efficiency and achieving their air leakage targets, which they often set below 

their climate zone standard of 3.0 ACH50. The California builders were less interested in the 

method given their state’s lack of air sealing standards, but agreed that it would be a useful tool 

in more extreme climates and could reduce rooftop solar costs in their net zero homes. The main 

hurdle to using aerosol sealing that all the builders expressed was the prohibitive cost. It was not 

clear to them whether costs could be reduced by eliminating other sealing materials, but many 
Aerosol Envelope Sealing of New Residences

94

were interested in experimenting further to determine what could be replaced. Many were also 

confident that with sufficient incentives and subsequent product scaling they could more easily 

sell customers on its incorporation into their home. Another significant challenge noted by one 

builder was preventing moisture intrusion in increasingly airtight homes; they expressed doubts 

that customers can be counted on to adequately maintain their ventilation systems, which become 

increasingly critical to home durability as envelope breathability decreases.

The aerosol envelope sealing process produced tighter homes, in addition to demonstrating a 

potential opportunity for cost savings in the construction process. A review of the standard air 

sealing performed by builders in the United States shows several areas where air sealing can be 

reduced or eliminated by applying aerosol sealing. By reducing other sealing work, builders can: 

(1) minimize material used for sealing a building, because aerosol sealing only applies material 

where leaks are present; (2) reduce the possibility of redundant sealing (e.g., sealing on both 

external and internal wall surfaces) while assuring a continuous air barrier is applied; and (3) 

reduce the number of trades involved in the air sealing process. 
Aerosol Envelope Sealing of New Residences

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Buildings. ASHRAE Standard 62.2-2010, Atlanta, GA. 

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Envelopes and Air Barrier Systems. ASTM International, West Conshohocken, PA. 

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ASTM E 779-10. 2010. Standard Test Method for Determining Air Leakage Rate by Fan 

Pressurization Method. ASTM International, West Conshohocken, PA. 

https://www.astm.org/Standards/E779.htm.

Bohac, D.L., B. Schoenbauer, J. Fitzgerald, C. Harrington, and M. Modera. 2016. “Using an 

Aerosol Sealant to Reduce Multifamily Envelope Leakage.” ACEEE Summer Study 

Proceedings. Pacific Grove, CA.

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Chan, WR, J. Joh, and M. Sherman. 2013. “Analysis of air leakage measurements of US 

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ts%20v101%202015-06-26_clean_fillable_508.pdf?8255-eac0. 
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Harrington, C., and D. Springer. 2015. Field Trial of an Aerosol-Based Enclosure Sealing 

Technology. Alliance for Residential Building Innovation for the U.S. Department of Energy 

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Harrington, C., and M. Modera. 2012. Laboratory Testing of Aerosol for Enclosure Air Sealing. 

KNDJ-0-40343-00. U.S. Department of Energy Building America Program. 

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Hendron, R. and C. Engebrecht. 2010. Building America House Simulation Protocols. U.S. 

Department of Energy Building America Program. TP-550-49426. 

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Lstiburek, Joseph. 2015. “BSI-084: Forty Year of Air Barriers*—The Evolution of the 

Residential Air Barrier.” Building Science Corporation. 

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Maxwell, S., D. Berger, and C. Harrington. 2015. Apartment Compartmentalization With an 

Aerosol-Based Sealing Process. Consortium for Advanced Residential Building for the U.S. 

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Testing of an Aerosol-Based Technology for Sealing Ductwork.” ACEEE Summer Study 

Proceedings. Pacific Grove, CA.

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Appendix A. Builder Interview Script and Questions

Introduction: We are wrapping up our DOE Building America project on aerosol envelope 

sealing for new homes. We want your feedback about the aerosol envelope sealing process. It’s 

important for us to get the perspective of the builders who might be using this service. We are 

interested in what you see as the advantages and disadvantages about the process and how you 

would see it being incorporated into your construction process. I have about 10 questions that 

I’m hoping will provide a useful discussion about aerosol envelope sealing. I expect this will 

take about 20 to 30 minutes. 

Key study results: Before we get started, I wanted to share some of the key findings from our 

project. We sealed a total of 27 houses for 2 builders in California and 7 builders in Minnesota 

and Illinois. Overall, the sealing was very successful. There was typically a 70% to 80% 

reduction in house leakage, and the houses ended up well below code-required tightness levels. 

California: For the 6 unvented attic houses in California, the sealing reduced leakage by an 

average of 80% and got them about 70% below their leakage target of 5.0 ACH50. The aerosol 

sealing allows the houses to get tight enough without the need for spray foam under the roof 

deck so that other types of insulation can be used. For the 5 vented attic houses, the sealing 

reduced leakage by 70% and got them about 42% below target. The unvented attic houses were 

sealed near the beginning of construction and the vented attic houses toward the end. 

Minnesota: For the 7 houses we sealed for the first Minnesota builder we had an average leakage 

reduction of almost 75%, and the houses ended up a little over 70% tighter than the 3.0 ACH50

code requirement. All of those houses were sealed before wall insulation and drywall. For the 

houses for the other 6 builders, the average reduction was 75% and the houses ended up being 

77% tighter than code. Half the houses met the 0.6 ACH50 Passive House tightness requirement 

and only 1 house was above 1.0 ACH50. Almost all of the houses were sealed before wall 

insulation and drywall, but at couple were sealed at the end of construction. 

1. What is the typical range of leakage for your houses? Do you have a target leakage? 

What would be the biggest challenges in using aerosol for your houses? (cost, 

scheduling) 

2. What would be the most significant benefits in using aerosol for your houses? (reliable 

leakage, reduced leakage, reduced QC, tighter houses, increased utility efficiency 

incentives, selling point for buyers, reduced call-backs, ability to pass blower door air 

leakage requirement)

3. At what point of the construction process would it make most sense for you to use 

aerosol? (Try to be specific. List of typical construction steps. If they don’t have a clear 

idea of when during construction they would want to apply aerosol, ask if they would 

expect to do the sealing before or after these steps [or if it doesn’t matter or they don’t 

know]: (a) can foam sealing of wire/plumbing penetrations, (b) caulk gaps between studs 
Aerosol Envelope Sealing of New Residences

99

and base plate/subfloor, (c) rim joist spray foam, (d) wall insulation, (e) drywall, (f) trim 

work) 

4. What current air sealing do you think you could eliminate if you were using aerosol 

sealing? (airtight electric boxes, poly on exterior walls, open-cell foam, caulking [type of 

locations], can foam [type of locations]) 

5. We are interested in the possible cost savings for eliminating some of these current 

sealing methods. Is it possible for you to make an estimate of the cost savings? If so, 

could you provide that to us? (consider man hours, material, etc.)

6. Are there certain types of houses or construction where you think aerosol will be a better 

application? (slab-on-grade, townhouses, complicated framing, etc.) 

7. Are there other housing types or parts of the country where you think aerosol will have 

more impact?

8. What would it take for you to incorporate aerosol sealing into your construction process? 

9. Do you currently use energy-efficient homes and/or insulation and air sealing as a 

marketing tool? Now that you have witnessed the process and effectiveness of aerosol, 

could you use it as a future marketing tool? 

10. What information or sales material would be beneficial to show home buyers the benefits 

of aerosol? (cost savings calculator, pamphlets, real-world results, installation video) 

11. Comparted to other builders, are you currently using home comfort as a talking point 

with potential home buyers and/or energy cost savings as an advantage with your homes 

over other builders? 

12. Do you typically receive utility energy efficiency incentives for your houses? If so, do 

you think that consistently getting your houses to 0.5 to 1.0 ACH50 with aerosol would 

get you a higher incentive and, if so, how much more? If not, would you be more likely 

to purse getting incentives if you were using aerosol sealing? 
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Appendix B. Code Requirements for Vapor Retarders and 

Air Barriers

Vapor Retarder and Air Barriers: What’s the Difference? 

Moisture, in vapor form, can pass through the building assembly in two distinct ways: 

1. Vapor diffusion. The rate of movement by diffusion is determined by the vapor gradient 

and permeability of the materials. A vapor retarder is intended to retard diffusion. 

2. Air movement. Also known as convective mass transport, this is when the vapor within 

an air mass is carried through the building assembly by airflow. The rate of flow is 

determined by the leakage characteristic (i.e., restriction to air movement) and the air 

pressure gradient.

Vapor retarders are not called “vapor barriers” for a reason. Vapor retarders only need to limit 

the amount of moisture diffusion through the wall or other building assembly where they are 

used. However, water vapor diffusion is often an insignificant source of envelope moisture 

transport (Straube 2007).

Moisture condensation from winter exfiltrating air and summer infiltrating air through air leaks 

in wall and other envelope cavities is one of the two major sources of moisture in above-grade 

enclosures (rain is the other). An air barrier is intended to limit air leakage that could also 

transport vapor via convection into the building assembly. An effective building assembly must 

be designed to limit air leaks through the assembly and properly control vapor diffusion. This 

combined impact of air movement (e.g., convection) and diffusion is a critical distinction in the 

design of durable wall assemblies. 

Air barriers can be located at the exterior or interior surface of the envelope cavity—or both. 

Either location will control the movement of air through cavity insulation systems. However, an 

exterior air barrier will stop the wind-washing of outdoor air through the cavity. An interior air 

barrier will control the movement of air into the cavity—if there is a driving force to move 

indoor air into the cavity and back to the indoors. 

The location of the air barrier produced by aerosol sealing will depend on when during 

construction the sealing is applied. When aerosol sealing is done prior to wall insulation and 

drywall, the air barrier will be produced at the exterior surface. Generally, the aerosol sealant 

will seal gaps at the exterior sheathing. These gaps may occur between the sheathing and 

framing, penetrations through the sheathing and framing, and gaps between framing. When 

aerosol sealing is done after drywall, the air barrier is created at the interior drywall. There are 

many products that can serve as a vapor retarder, an air barrier, or both depending on their 

properties. 
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Code Requirements for Vapor Retarders 

Chapter 7 (Wall Covering), Section R702 (Interior Wall Covering) of the 2015 Minnesota 

Building Code contains provisions for the use of vapor retarders for moisture control in abovegrade walls. The air barrier and vapor retarder requirements for below-grade walls are different 

from those for above-grade walls. Aerosol sealing is not likely to impact the design and 

implementation of the below-grade portion of the house and are not addressed here. The 

following are the relevant sections for above-grade walls:

Code Definitions

Vapor Retarder Class. A measure of the ability of a material or assembly to limit the amount of 

moisture that passes through that material or assembly. Vapor retarder class shall be defined 

using the desiccant method with Procedure A of ASTM E 96 as follows: 

Class I: Permeance level of 0.1 perm or less 

Class II: Permeance level between 0.1 perm and 1.0 perm 

Class III: Permeance level between 1.0 perm and 10 perms

Code Sections

R702.7 Vapor retarders. A Class I or II vapor retarder is required on the interior side of frame 

walls in Climate Zones 6 and 7. Class II vapor retarders are permitted only when specified on the 

construction documents. 

R702.7.1 Class III vapor retarders. Class III vapor retarders shall be permitted where any one of 

the conditions in Table R702.7.1 is met. 
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Table 16. Table R702.7.1: Class III Vapor Retarders Permitted For the Following

Climate Zone Class III Vapor Retarders Permitted For:* 

Marine 4

Vented cladding over wood structural panels.

Vented cladding over fiberboard.

Vented cladding over gypsum.

Insulated sheathing with R-value ≥ 2.5 over 2×4 wall.

Insulated sheathing with R-value ≥ 3.75 over 2×6 wall.

5 

Vented cladding over wood structural panels.

Vented cladding over fiberboard.

Vented cladding over gypsum.

Insulated sheathing with R-value ≥ 5 over 2×4 wall.

Insulated sheathing with R-value ≥ 7.5 over 2×6 wall.

6 

Vented cladding over fiberboard.

Vented cladding over gypsum.

Insulated sheathing with R-value ≥ 7.5 over 2×4 wall.

Insulated sheathing with R-value ≥ 11.25 over 2×6 wall.

7 and 8 Insulated sheathing with R-value ≥ 10 over 2×4 wall.

Insulated sheathing with R-value ≥ 15 over 2×6 wall.

*Spray foam with a minimum density of 2 lb/ft3 applied to the interior cavity side of wood structural panels, 

fiberboard, insulating sheathing or gypsum is deemed to meet the insulating sheathing requirement where 

the spray foam R-value meets or exceeds the specified insulating sheathing R-value.

R702.7.2 Material vapor retarder class. The vapor retarder class shall be based on the 

manufacturer’s certified testing or a tested assembly.

The following shall be deemed to meet the class specified:

Class I: Sheet polyethylene, unperforated aluminum foil. 

Class II: Kraft-faced fiberglass batts.

Class III: Latex or enamel paint.

Code Requirements for Air Barriers 

Chapter 4 (Residential Energy Efficiency), Section R402 (Building Thermal Envelope) of the 

2015 Minnesota Residential Energy Code contains provisions to limit air leakage in the building 

thermal envelope. Following are the relevant sections:

Code Definitions

AIR BARRIER. Material(s) assembled and joined together to provide a barrier to air leakage 

through the building envelope. An air barrier may be a single material or a combination of 

materials.

CONTINUOUS AIR BARRIER. A combination of materials and assemblies that restrict or 

prevent the passage of air through the building thermal envelope. 
Aerosol Envelope Sealing of New Residences

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Code Sections

R402.4 Air leakage (Mandatory). The building thermal envelope shall be constructed to limit air 

leakage in accordance with the requirements of Sections R402.4.1 through R402.4.4. 

R402.4.1 Building thermal envelope. The building thermal envelope shall comply with Sections 

R402.4.1.1 and R402.4.1.2. The sealing methods between dissimilar materials shall allow for 

differential expansion and contraction. 

The building thermal envelope must be constructed to limit air leakage. 
Aerosol Envelope Sealing of New Residences

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Table 17. Table R402.4.1.1: Air Barrier and Insulation Installation Criteria

Component Criteria

Air barrier and thermal barrier

A continuous air barrier shall be installed in the building envelope. 

Exterior thermal envelope contains a continuous air barrier. 

Breaks or joints in the air barrier shall be sealed. Air-permeable 

insulation shall not be used as a sealing material.

Ceiling/attic

The air barrier in any dropped ceiling/soffit shall be aligned with 

the insulation and any gaps in the air barrier sealed. Access 

openings, drop down stair or knee wall doors to unconditioned 

attic spaces shall be sealed.

Walls

Corners and headers shall be insulated, and the junction of the 

foundation and sill plate shall be sealed. The junction of the top 

plate and top of exterior walls shall be sealed. Exterior thermal 

envelope insulation for framed walls shall be installed in 

substantial contact and continuous alignment with the air barrier. 

Knee walls shall be sealed.

Windows, skylights, and 

doors

The space between window/door jambs and framing and skylights 

and framing shall be sealed.

Rim joists Rim joists shall be insulated and include the air barrier.

Floors (including abovegarage and cantilevered 

floors)

Insulation shall be installed to maintain permanent contact with 

underside of subfloor decking. The air barrier shall be installed at 

any exposed edge of insulation.

Crawl space walls

Where provided in lieu of floor insulation, insulation shall be 

permanently attached to the crawlspace walls. Exposed earth in 

unvented crawl spaces shall be covered with a Class I vapor 

retarder with overlapping joints taped.

Shafts, penetrations Duct shafts, utility penetrations, and flue shafts opening to exterior 

or unconditioned space shall be sealed.

Narrow cavities

Batts in narrow cavities shall be cut to fit, or narrow cavities shall 

be filled by insulation that on installation readily conforms to the 

available cavity space.

Garage separation Air sealing shall be provided between the garage and conditioned 

spaces.

Recessed lighting Recessed light fixtures installed in the building thermal envelope 

shall be airtight, IC rated, and sealed to the drywall.

Plumbing and wiring

Batt insulation shall be cut neatly to fit around wiring and plumbing 

in exterior walls, or insulation that on installation readily conforms 

to available space shall extend behind piping and wiring.

Shower/tub on exterior wall

Exterior walls adjacent to showers and tubs shall be insulated and 

the air barrier installed separating them from the showers and 

tubs.

Electrical/phone box on 

exterior walls

The air barrier shall be installed behind electrical or 

communication boxes or air sealed boxes shall be installed.

HVAC register boots HVAC register boots that penetrate building thermal envelope 

shall be sealed to the subfloor or drywall.

Fireplace An air barrier shall be installed on fireplace walls. Fireplaces shall 

have gasketed doors.
Aerosol Envelope Sealing of New Residences

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Minnesota Code Analysis: 

Vapor retarders and air barriers provide separate and distinct functions 

a. Vapor retarders can be either: 

i. Class I in all cases

ii. Class II when specified on the construction documents, or 

iii. Class III when one of the conditions in Table R702.7.1 is met 

b. Vapor retarders are required on the interior side of framed walls

c. Vapor retarders are NOT required to be continuous 

d. Vapor retarders are NOT required to be sealed

e. Air barriers can be a combination of materials

f. Air barriers must be continuous 

g. Air barriers must be sealed

h. Air barriers are NOT required to be on the interior side of framed walls

i. Air sealing details must be included with the construction documents [1322.0103]. 
Aerosol Envelope Sealing of New Residences

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Appendix C. Air Sealing Assessment Tables

On-site visual inspections were used to qualitatively assess the envelope air barrier of recently 

completed houses. A checklist of common leakage sites was used to guide the inspection process 

and provide structure to the results. The inspections provided information about the quality of 

sealing work (excellent, acceptable, poor, no attempt), who performed the sealing, what material 

was used, and the potential for aerosol sealing to replace current methods. The following tables 

show information collected for the participating builders. 

Table 18. California: Air Unvented Attics With Spray Foam Insulation

Category Component Who Does Sealing? Material Used for 

Sealing?

Can 

AeroBarrier 

Replace?

Quality of 

Seal Work

Ceiling/Attic

Attic access panels N/A Gasketed door No Excellent

Drop down stairs N/A N/A N/A N/A

Whole-house fans N/A N/A N/A N/A

Recessed lighting fixtures N/A Gasketed fixture Yes Excellent

Drop ceiling/soffit Insulation contractor Closed-cell spray foam Yes Excellent

Walls

Exterior walls Insulation contractor Gasket/OSB N/A Excellent

Sill plate Carpentry contractor Gasket/OSB Yes Acceptable

Top plate Insulation contractor Gasket Yes Acceptable

Drywall to top plate Insulation contractor Gasket Yes Excellent

Interior partition wall to 

exterior wall

Carpentry contractor/ 

insulation contractor

Solid blocking/

Can foam Yes Excellent

Knee walls Carpentry contractor OSB N/A Excellent

Windows, 

Skylights, and 

Doors

Rough openings Insulation contractor Can foam Yes Excellent

Rim Joists Insulation contractor Open-cell spray foam Yes Excellent

Shafts, 

Penetrations

to 

Unconditioned 

Spaces

Ducts Insulation contractor Can foam/

open-cell spray foam No Excellent

Flues Insulation contractor Can foam/

open-cell spray foam No Excellent

Shafts Insulation contractor Can foam/

open-cell spray foam No Excellent

Plumbing Insulation contractor Can foam/

open-cell spray foam Yes Excellent

Piping Insulation contractor Can foam/

open-cell spray foam Yes Excellent

Wiring Insulation contractor Can foam/

open-cell spray foam Yes Excellent

Exhaust fans Insulation contractor Can foam/

open-cell spray foam Yes Excellent

Other N/A N/A N/A N/A

Garage 

Separation 

Walls

Floor cavities aligned with 

garage separation walls

Carpentry contractor/ 

insulation contractor

Blocking/

open-cell spray foam No Excellent

Other

Shower/tub on exterior wall Carpentry contractor/ 

insulation contractor

OSB/ 

open-cell spray foam Yes Excellent

Stair stringer on exterior 

wall N/A None Yes N/A

Fireplace on exterior wall N/A N/A N/A N/A

Electrical/low-voltage 

boxes on exterior walls Insulation contractor Can foam/open-cell spray foam Yes Excellent

HVAC register boots that 

penetrate building thermal 

envelope

Insulation contractor Open-cell spray foam Yes N/A
Aerosol Envelope Sealing of New Residences

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Table 19. California: Air Unvented Attics With Netted Insulation

Category Component Who Does Sealing? Material Used for 

Sealing?

Can 

AeroBarrier 

Replace?

Quality of 

Seal Work

Ceiling/Attic

Attic access panels Insulation contractor Gasketed door No Excellent

Drop down stairs N/A N/A N/A N/A

Whole-house fans N/A N/A N/A N/A

Recessed lighting fixtures Insulation contractor Gasketed fixture Yes Excellent

Drop ceiling/soffit Insulation contractor Drywall Yes Excellent

Walls

Exterior walls Insulation contractor Gasket/foam board N/A Excellent

Sill plate Insulation contractor Gasket/caulk Yes Acceptable

Top plate Insulation contractor Gasket Yes Acceptable

Drywall to top plate Insulation contractor Gasket Yes Excellent

Interior partition wall to 

exterior wall Insulation contractor Gasket Yes Excellent

Knee walls Insulation contractor Six-sided sealed/

fiberboard/Tyvek Yes Excellent

Windows, 

Skylights, and 

Doors

Rough openings Insulation contractor Can foam Yes Excellent

Rim Joists Insulation contractor Can foam Yes Excellent

Shafts, 

Penetrations

to 

Unconditioned 

Spaces

Ducts Insulation contractor Can foam No Excellent

Flues Insulation contractor Can foam No Excellent

Shafts Insulation contractor Can foam No Excellent

Plumbing Insulation contractor Can foam No Excellent

Piping Insulation contractor Can foam No Excellent

Wiring Insulation contractor Can foam No Excellent

Exhaust fans Insulation contractor Gasket/butyl tape Yes Excellent

Other N/A N/A N/A N/A

Garage 

Separation 

Walls

Floor cavities aligned with 

garage separation walls

Drywall/insulation 

contractor Drywall/gasket No Excellent

Other

Shower/tub on exterior wall Carpentry contractor/ 

insulation contractor OSB/foam Yes Excellent

Stair stringer on exterior 

wall

Carpentry contractor/ 

insulation contractor Gasket Yes N/A

Fireplace on exterior wall Carpentry contractor/ 

insulation contractor Six-sided box No Acceptable

Electrical/low-voltage 

boxes on exterior walls Insulation contractor Quick flash Yes Excellent

HVAC register boots that 

penetrate building thermal 

envelope

Insulation contractor Sealed to sheetrock w/ 

butyl tape

Yes N/A
Aerosol Envelope Sealing of New Residences

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Table 20. California: Vented Attics

Category Component Who Does Sealing? Material Used for 

Sealing?

Can 

AeroBarrier 

Replace?

Quality of 

Seal Work

Ceiling/Attic

Attic access panels Gasketed door No Excellent

Drop down stairs N/A N/A N/A N/A

Whole-house fans N/A N/A N/A N/A

Recessed lighting fixtures N/A Gasketed fixture Yes Excellent

Drop ceiling/soffit Insulation contractor Closed-cell spray foam Yes Excellent

Walls

Exterior walls Insulation contractor Gasket/OSB N/A Excellent

Sill plate Carpentry contractor Gasket/OSB Yes Acceptable

Top plate Insulation contractor Gasket Yes Acceptable

Drywall to top plate Insulation contractor Gasket Yes Excellent

Interior partition wall to 

exterior wall

Carpentry contractor/ 

insulation contractor

Solid blocking/can 

foam Yes Excellent

Knee walls Carpentry contractor OSB No Excellent

Windows, 

Skylights, and 

Doors

Rough openings Insulation contractor Can foam Yes Excellent

Rim Joists Insulation contractor Can foam Yes Excellent

Shafts, 

Penetrations

to 

Unconditioned 

Spaces

Ducts Insulation contractor Can foam No Excellent

Flues Insulation contractor Can foam No Excellent

Shafts Insulation contractor Can foam No Excellent

Plumbing Insulation contractor Can foam Yes Excellent

Piping Insulation contractor Can foam Yes Excellent

Wiring Insulation contractor Can foam Yes Excellent

Exhaust fans Insulation contractor Can foam Yes Excellent

Other N/A

Garage 

Separation 

Walls

Floor cavities aligned with 

garage separation walls

Carpentry contractor/ 

insulation contractor Blocking/can foam No Excellent

Other

Shower/tub on exterior wall Carpentry contractor/ 

insulation contractor OSB/can foam Yes Excellent

Stair stringer on exterior 

wall N/A None Yes N/A

Fireplace on exterior wall N/A N/A N/A N/A

Electrical/low-voltage 

boxes on exterior walls Insulation contractor Can foam Yes Excellent

HVAC register boots that 

penetrate building thermal 

envelope

Insulation contractor Can foam Yes N/A
Aerosol Envelope Sealing of New Residences

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Table 21. First Minnesota Builder (#3)

Category Component Who Does Sealing? Material Used for 

Sealing?

Can 

AeroBarrier 

Replace?

Quality of 

Seal Work

Ceiling/Attic

Attic access panels Drywall contractor Ceiling texture coat No Poor

Drop down stairs N/A N/A N/A N/A

Whole-house fans N/A N/A N/A N/A

Recessed lighting fixtures Insulation contractor/ 

electrician 

Polyethylene sheet/ 

gasketed fixture Yes Excellent

Drop ceiling/soffit N/A N/A N/A N/A

Walls

Exterior walls Insulation contractor Polyethylene sheet N/A Excellent

Sill plate Carpentry contractor Sill seal/caulk Yes Acceptable

Top plate Insulation contractor Polyethylene sheet/ 

caulk Yes Acceptable

Drywall to top plate N/A N/A

Interior partition wall to 

exterior wall Carpentry contractor Polyethylene sheet/ caulk Yes Excellent

Knee walls N/A N/A N/A N/A

Windows,

Skylights, and 

Doors

Rough openings Insulation contractor Can foam Yes Excellent

Rim Joists Insulation contractor Closed-cell spray foam Yes Excellent

Shafts, 

Penetrations

to 

Unconditioned 

Spaces

Ducts Insulation contractor Can foam No Excellent

Flues Insulation contractor Can foam No Excellent

Shafts Insulation contractor Can foam No Excellent

Plumbing Insulation contractor Can foam Yes Excellent

Piping Insulation contractor Can foam Yes Excellent

Wiring Insulation contractor Can foam Yes Excellent

Exhaust fans Insulation contractor Can foam No Excellent

Other

Garage 

Separation 

Walls

Floor cavities aligned with 

garage separation walls

Carpentry contractor/ 

insulation contractor

OSB/closed-cell spray 

foam No Excellent

Other

Shower/tub on exterior wall Carpentry contractor OSB/polyethylene sheet Yes Excellent

Stair stringer on exterior 

wall Carpentry contractor Polyethylene sheet Yes Excellent

Fireplace on exterior wall Carpentry contractor OSB/polyethylene sheet No Excellent

Electrical/low-voltage 

boxes on exterior walls

Insulation contractor/ 

electrician 

Polyethylene sheet/ 

caulk/casketed boxes Yes Excellent

HVAC register boots that 

penetrate building thermal 

envelope

Insulation contractor Can foam Yes Excellent
Aerosol Envelope Sealing of New Residences

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Table 22. Second Minnesota Builder (#4)

Category Component Who Does Sealing? Material Used for 

Sealing?

Can 

AeroBarrier 

Replace?

Quality of 

Seal Work

Ceiling/Attic

Attic access panels Drywall contractor Ceiling texture coat No Poor

Drop down stairs N/A N/A N/A N/A

Whole-house fans N/A N/A N/A N/A

Recessed lighting fixtures Insulation contractor/ 

electrician 

Polyethylene sheet/ 

gasketed fixture Yes Excellent

Drop ceiling/soffit N/A Yes Excellent

Walls

Exterior walls Insulation contractor Polyethylene sheet N/A Excellent

Sill plate Carpentry contractor Sill seal/caulk Yes Acceptable

Top plate Insulation contractor Polyethylene sheet/ 

caulk Yes Acceptable

Drywall to top plate N/A N/A N/A N/A

Interior partition wall to 

exterior wall Carpentry contractor Polyethylene sheet/ caulk Yes Excellent

Knee walls Insulation contractor Polyethylene sheet/ 

caulk N/A N/A

Windows, 

Skylights, and 

Doors

Rough openings Window installation 

contractor Can foam Yes Excellent

Rim Joists Insulation contractor Can foam Yes Excellent

Shafts, 

Penetrations

to 

Unconditioned 

Spaces

Ducts Insulation contractor Can foam No Excellent

Flues Insulation contractor Can foam No Excellent

Shafts Insulation contractor Can foam No Excellent

Plumbing Insulation contractor Can foam Yes Excellent

Piping Insulation contractor Can foam Yes Excellent

Wiring Insulation contractor Can foam Yes Excellent

Exhaust fans Insulation contractor Polyethylene sheet/ 

caulk No Excellent

Other

Garage 

Separation 

Walls

Floor cavities aligned with 

garage separation walls

Carpentry contractor/ 

insulation contractor

OSB/closed-cell spray 

foam No Excellent

Other

Shower/tub on exterior wall Carpentry contractor OSB/polyethylene sheet Yes Excellent

Stair stringer on exterior 

wall Carpentry contractor Polyethylene sheet Yes Excellent

Fireplace on exterior wall Carpentry contractor OSB/polyethylene sheet No Excellent

Electrical/low-voltage 

boxes on exterior walls

Insulation contractor/ 

electrician 

Polyethylene sheet/ 

caulk/casketed 

boxes/can foam at wire 

penetrations

Yes Excellent

HVAC register boots that 

penetrate building thermal 

envelope

N/A N/A N/A N/A
Aerosol Envelope Sealing of New Residences

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Appendix D. Content for the Building America Solution 

Center

This appendix includes information from the forthcoming Air Sealing the Envelope with Aerosol 

Sealant Guide that will be published in the Building America Solution Center. 

Guide Title: Air Sealing the Envelope with Aerosol Sealant 

Taxonomy Number: TE 5.2.8 

Keywords: Air sealing, air barriers, openings, testing

Climate Zone: All climate zones 

Construction Type: New construction 

One-Liner: Guide describing aerosol method to seal air leakage in new home envelopes.

Authors: Center for Energy and Environment, David Bohac, dbohac@mncee.org 

UC Davis/Western Cooling Efficiency Center (WCEC), Curtis Harrington, 

csharrington@ucdavis.edu 

Scope 

Using an aerosol sealing technology to seal new homes during the construction process. 

• Choose the stage of construction to apply the sealing. The process can be applied at any 

point after the primary air barrier is in place. For example, the sealing can be conducted 

early in construction for homes with sealed attics or vented attic homes that use poly 

sheeting or drywall on the ceiling. The sealing will be done late in construction for vented 

attic houses that install the drywall on the ceiling at the same time as it is installed on the

rest of the house. 

• For best performance, large gaps (more than 0.5-in. across) should be sealed prior to 

installing.

• Temporarily seal all designed openings in the house exterior that are not intended to 

remain open (e.g., exhaust fan ducts, ventilation system ducts, combustion air ducts, and 

doors leading to outside). 

• Temporarily cover finished floors and other finished horizontal surfaces. 

• Evacuate the building before sealing. 

• Place aerosol sealant sprayers throughout the house to achieve a uniform sealant “fog.” 

• Use a blower in an exterior door to pressurize the house and force the air/sealant fog 

through leaks in the envelope. The sealant will attach to the edges of the leaks and fill the 

gaps over the 30- to 120-minute sealing period. 
Aerosol Envelope Sealing of New Residences

112

• Seal building to target air leakage. Consider future work on building and possibly seal 

10%–20% tighter than target leakage.

o If goal is to seal as tight as possible, seal until sealing rate drops below about 5 

CFM50/min.

• Remove equipment and temporary coverings. Clean any unwanted sealant deposition 

from surfaces.

• Allow building to air out for 30 minutes before allowing others into the space. 

See the Compliance section for related codes and standards, and criteria to meet national 

programs such as ENERGY STAR and DOE’s Zero Energy Ready Home program. 

Figure 63. Aerosol sealing process

pump and

sealant

air

aerosol 

sprayer

blower
Aerosol Envelope Sealing of New Residences

113

Description 

In many parts of the United States, house envelopes are notoriously leaky, with unintended flows 

between conditioned and unconditioned spaces that result in additional space heating and cooling 

equipment loads. Although voluntary codes and standards for envelope tightness have existed for 

decades, only recently have these codes included mandatory envelope leakage requirements with 

verification by performance testing. Current state-of-the-art methods for envelope air sealing rely 

on contractor personnel to identify and manually seal typical leakage locations. The achieved 

airtightness levels can be highly variable and are based on the time allotted, accessibility of 

leaks, as well as the vigilance and experience of the contractor who performs the work. 

The aerosol envelope sealing technology uses an automated method to satisfy the envelope 

sealing requirement. The process involves pressurizing the building for an hour or two while 

applying an aerosol sealant “fog” to the building interior (see Figure 64). As air escapes the 

building through leaks in the envelope, the sealant particles are carried to the leaks where they 

impact and stick, sealing the leaks (see Figure 65). A calibrated blower is used to facilitate the 

sealing process, and provide real-time feedback and a permanent record of the sealing. The 

technology is thus capable of simultaneously measuring, locating, and sealing leaks in a building 

automatically. 

Figure 64. Aerosol fog from spray head
Aerosol Envelope Sealing of New Residences

114

Figure 65. Aerosol sealant build-up on edge of leak

Figure 66. Blower door, sealant pump, and sealant setup in attached garage
Aerosol Envelope Sealing of New Residences

115

All locations not intended to be sealed should be temporarily blocked during the sealing process. 

In addition, finished horizontal surfaces that cannot have sealant deposition should be covered. 

In general, for new construction the sealing can be performed before there are finished surfaces 

in the home that would need covering other than window tracks and weep holes. Figure 67, 

Figure 68, and Figure 69 display typical temporary seals. The sealant is cleanable from many 

surfaces.

Figure 67. Temporary cover over sprinkler head

Figure 68. Temporary cover over open plumbing pipes
Aerosol Envelope Sealing of New Residences

116

Figure 69. Temporary cover over tub and plumbing fixture 

The advantages of the aerosol sealing process are that:

• The sealant fog finds its way to the leaks automatically. It is not necessary to manually 

locate the leaks, which takes the guesswork out of where to seal. 

• Leaks are sealed simultaneously over 1 to 2 hours. 

• The aerosol seals are highly effective. When large gaps are pre-sealed prior to aerosol 

sealing, a house leakage below 0.5 to 1.0 ACH50 can be achieved on a consistent basis. 

• The system measures leakage in real time, allowing the installer to ensure the target 

leakage is met.

• The tedious process of caulking, foaming, and/or taping gaps that can be challenging to 

quality control is replaced with a more productive, automated method. 

• Less material is used because sealant is only deposited on leaks, not the entire structure.

Figure 70 through Figure 75 provide examples of typical seals produced by the aerosol sealing 

method. 
Aerosol Envelope Sealing of New Residences

117

Figure 70. Seal (gray material) formed between gap in foam

Figure 71. Seal around electric box on exterior wall
Aerosol Envelope Sealing of New Residences

118

Figure 72. Seal between electrical box and drywall; the seal on the sides of the box is made further back in 

the crevice and not visible on the surface

Figure 73. Seal between plumbing penetration and drywall
Aerosol Envelope Sealing of New Residences

119

Figure 74. Seal gap between framing

Figure 75. Seal between sheathing and framing
Aerosol Envelope Sealing of New Residences

120

Ensuring Success 

Visual Inspection

Visually inspect envelope penetrations and transitions to identify gaps wider than about 0.5 in. 

that need to be manually sealed prior to the aerosol sealing. It is best to work with the builder to 

identify common locations for large gaps in the envelope and have them seal the gaps. In 

general, larger gaps missed during the inspection do not pose significant issues, but rather result 

in longer sealing times, increased sealant material use, and higher leakage when aerosol sealing 

is complete.

Protect Finished Horizontal Surfaces

The sealing process can leave a small amount of sealant on horizontal surfaces. Finished 

horizontal surfaces need to be covered with poly sheets or other protection prior to sealing. 

Install at Earliest Opportunity

In general, the earlier in the construction process that the aerosol sealing process can be applied 

the better (e.g., after first coat of mud on drywall but before texture and paint). Installing earlier 

in the construction process leads to reduced prep time and clean up. Aerosol sealing can be 

complete as soon as the home can be pressurized. For conditioned attics this means application 

can occur at rough-in. For vented attics, the application would occur after the first coat of mud 

on the drywall, unless drywall or poly sheeting is installed on the ceiling of the top floor. 

Temporary Seal Envelope Openings

Temporarily seal designed opening in the envelope that are not intended to be sealed. This 

includes dryer vents, exhaust fan vents, combustion air ducts, ventilation system ducts, and dry 

plumbing traps or waste lines. You should also seal window weep holes so that they do not 

become plugged. 

Air Out House After Sealing

Once sealing is complete and a post-seal test has been performed, open as many windows as 

possible to help disperse the fog of sealant. It is best to start with the windows furthest from the 

blower door fan location, keeping a minimum positive pressure of 50 Pa until all windows are 

open. Then increase the fan airflow to maximum speed for at least 30 minutes. 

Climate

Applicable to any climate. Follow manufacturer minimum temperature application requirements. 

For hot-humid climates applying the aerosol sealing early in construction to create the air barrier 

toward the exterior side of the walls may reduce wind-washing and improve durability. 
Aerosol Envelope Sealing of New Residences

121

Training 

Right/Wrong Images: 

Wrong: Envelope gaps greater than 0.5-in. wide should be sealed prior to aerosol sealing 

Right: Only narrow gap remains for aerosol sealing 
Aerosol Envelope Sealing of New Residences

122

Wrong: Poly sheet pulled away from framing during sealing due to poor stapling and 

caulking 

Right: Poly sheet properly stapled and caulked for aerosol sealing at early phase of 

construction; a high level of care is required for the poly to hold up to the high pressurization 

(100 Pa) that occurs during sealing 
Aerosol Envelope Sealing of New Residences

123

Wrong: Batt insulation installed prior to aerosol sealing at early phase of construction 

Right: Wall cavities exposed to allow aerosol to seal gaps between sheathing and sill plate 
Aerosol Envelope Sealing of New Residences

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Resources 

Presentations

“Aerosol Sealing of Building Envelopes in New Construction” 

https://youtu.be/Uj5ndzkQ6xM

Authors: Dave Bohac and Curtis Harrington

Organizations: Center for Energy and Environment and UC Davis/WCEC

“Auto-Sealing New Home Leaks with Aerosols” 

ACEEE Summer Study 2018 

https://www.mncee.org/MNCEE/media/Program-Resource/ACEEE-2018_Aerosol-Sealing-inNew-Construction_080218.pdf

Authors: Dave Bohac and Curtis Harrington 

Organizations: Center for Energy and Environment and UC Davis/WCEC

Articles 

“Air Sealing with AeroBarrier” 

https://www.homeenergy.org/show/article/nav/buildingenvelope/id/2278

Authors: Dave Bohac and Curtis Harrington 

Organizations: Center for Energy and Environment and UC Davis/WCEC

Videos

“Aerosol Sealing for Multifamily Applications” 

https://www.mncee.org/resources/resource-center/info-visualization/aerosol-sealing-formultifamily-application/

Organization: Center for Energy and Environment

Compliance 

Code Compliance Brief

Aerosol Sealing Building Enclosures, Single and Multifamily Dwellings - Code Compliance 

Brief

https://basc.pnnl.gov/code-compliance/aerosol-sealing-building-enclosures-single-andmultifamily-dwellings-code. 

U.S. Department of Energy Zero Energy Ready Home 

The DOE Zero Energy Ready Home National Program Prescriptive Path Requirements 

(https://www.energy.gov/eere/buildings/guidelines-participating-doe-zero-energy-ready-homeprogram) specify that the dwelling meets the requirements of Exhibit 2: DOE Zero Energy 

Ready Home Target Home Infiltration – Detached Dwellings (ACH50): 3 for climate zones 1–2, 

2.5 for climate zones 3–4, 2 for climate zones 5–7, 1.5 for climate zone 8.

Infiltration – Attached Dwellings (ACH50): 3 for all climate zones.

ENERGY STAR Certified Homes 

The ENERGY STAR Certified Homes National Program Requirements

https://www.energystar.gov/partner_resources/residential_new/homes_prog_reqs/national_page.
Aerosol Envelope Sealing of New Residences

125

National Program Requirements 

The ENERGY STAR Reference Design Home is the set of efficiency features modeled to 

determine the ENERGY STAR ERI Target for each home pursuing certification. Therefore, 

while the features below are not mandatory, if they are not used then other measures will be 

needed to achieve the ENERGY STAR ERI Target. In addition, note that the Mandatory 

Requirements for All Certified Homes, Exhibit 2, contain additional requirements such as total 

duct leakage limits, minimum allowed insulation levels, and minimum allowed fenestration 

performance. Therefore, EPA recommends that partners review the documents in Exhibit 2 prior 

to selecting measures.

Version 3.0 - Exhibit 1 ENERGY STAR Reference Design Home. Infiltration rates modeled as 

follows: 

• 6.0 ACH50 in climate zones 1 and 2 

• 5.0 ACH50 in climate zones 3 and 4 

• 4.0 ACH50 in climate zones 5, 6, and 7 

• 3.0 ACH50 in climate zone 8. 

Version 3.1 - Exhibit 1 ENERGY STAR Reference Design Home. Infiltration rates modeled as 

follows: 

• 4.0 ACH50 in climate zones 1 and 2 

• 3.0 ACH50 in climate zones 3, 4, 5, 6, 7, and 8. 

Please see the ENERGY STAR Certified Homes Implementation Timeline for the program 

version and revision currently applicable in in your state. 

The ENERGY STAR Certified New Homes National Program Requirements lists the following 

criteria related to envelope leakage.

National Rater Field Checklist:

4. Air Sealing (Unless otherwise noted below, “sealed” indicates the use of caulk, foam, or 

equivalent material)

4.1 Ducts, flues, shafts, plumbing, piping, wiring, exhaust fans, and other penetrations to 

unconditioned space sealed, with blocking / flashing as needed. 

4.2 Recessed lighting fixtures adjacent to unconditioned space ICAT labeled and gasketed. 

Also, if in insulated ceiling without attic above, exterior surface of fixture insulated to ≥ R-10 in 

climate zones 4–8. 

4.3 Above-grade sill plates adjacent to conditioned space sealed to foundation or sub-floor. 

Gasket also placed beneath above-grade sill plate if resting atop concrete / masonry and adjacent 

to cond. space.1, 2

4.4 Continuous top plate or blocking is at top of walls adjoining unconditioned space, and 

sealed.

4.5 Drywall sealed to top plate at all unconditioned attic / wall interfaces using caulk, foam, 

drywall adhesive (but not other construction adhesives), or equivalent material. Either apply 

sealant directly between drywall and top plate or to the seam between the two from the attic 

above. 

4.6 Rough opening around windows and exterior doors sealed.3
Aerosol Envelope Sealing of New Residences

126

4.7 Walls that separate attached garages from occupiable space sealed and, also, an air barrier 

installed and sealed at floor cavities aligned with these walls.

4.8 In multifamily buildings, the gap between the common wall (e.g. the drywall shaft wall) 

and the structural framing between units sealed at all exterior boundaries. 

4.9 Doors adjacent to unconditioned space (e.g., attics, garages, basements) or ambient 

conditions made substantially airtight with weatherstripping or equivalent gasket. 

4.10 Attic access panels, drop-down stairs, and whole-house fans equipped with durable ≥ R10 cover that is gasketed (i.e., not caulked). Fan covers either installed on house side or 

mechanically operated.4

ENERGY STAR Notes

1. Existing sill plates (e.g., in a home undergoing a gut rehabilitation) on the interior side of 

structural masonry or monolithic walls are exempt from this Item. In addition, other existing sill 

plates resting atop concrete or masonry and adjacent to conditioned space are permitted, in lieu 

of using a gasket, to be sealed with caulk, foam, or equivalent material at both the interior seam 

between the sill plate and the subfloor and the seam between the top of the sill plate and the 

sheathing. 

2. In climate zones 1 through 3, a continuous stucco cladding system adjacent to sill and bottom 

plates is permitted to be used in lieu of sealing plates to foundation or sub-floor with caulk, 

foam, or equivalent material. 

3. In climate zones 1 through 3, a continuous stucco cladding system sealed to windows and 

doors is permitted to be used in lieu of sealing rough openings with caulk or foam. 

4. Examples of durable covers include, but are not limited to, pre-fabricated covers with integral 

insulation, rigid foam adhered to cover with adhesive, or batt insulation mechanically fastened to 

the cover (e.g., using bolts, metal wire, or metal strapping). 

Existing Homes 

The aerosol sealing method has been applied to existing homes and apartments on a limited 

basis. A 2019 DOE Building America project, Aerosol Sealing of Existing Residences, is 

developing protocols for sealing existing residences and documenting air leakage reductions. 

More Info 

Case Studies

Building America Case Study. Apartment Compartmentalization with an Aerosol-Based Sealing 

Process. 2015. Consortium for Advanced Residential Buildings. DOE/GO-102015-4621. 

https://energy.gov/sites/prod/files/2015/07/f24/ba_case_study_compartmentalization_aerosol.pdf

References and Resources

Bohac, David, Curtis Harrington, and Daniel Reif. 2018. “Auto-Sealing New Home Leaks with 

Aerosols.” ACEEE Summer Study on Energy Efficiency in Buildings. 

https://www.mncee.org/MNCEE/media/PDFs/Auto-Sealing-New-Home-Leaks-withAerosols.pdf

Bohac, David, Curtis Harrington, Ben Schoenbauer, Jose Garcia, Jim Fitzgerald, and Mark 

Modera. 2016. “Demonstrating the Effectiveness of an Aerosol Sealant to Reduce Multi-Unit 
Aerosol Envelope Sealing of New Residences

127

Dwelling Envelope Air Leakage.” Minnesota Department of Commerce. 

https://www.cards.commerce.state.mn.us/CARDS/security/search.do?method=showPoup&docu

mentId=%7bB7F5C928-D411-4B9E-B83F90E856DCC11F%7d&documentTitle=402271&documentType=6

Harrington, Curtis, and David Springer. 2015. Field Trial of an Aerosol-Based Enclosure Sealing 

Technology. Alliance for Residential Building Innovation for the U.S. Department of Energy 

Building America Program. DOE/GO-102015-4728. 

https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/aerosol-basedenclosure-sealing-technology.pdf

Maxwell, S., D. Berger, and C. Harrington. 2015. Apartment Compartmentalization with an 

Aerosol-Based Sealing Process. Consortium for Advanced Residential Buildings for the U.S. 

Department of Energy Building America Program. DOE/GO-102015-4620. 

https://www1.eere.energy.gov/buildings/publications/pdfs/building_america/apartmentcompartmentmentalization-aerosol-sealing.pdf

Harrington, Curtis, and Mark Modera. 2012. Laboratory Testing of Aerosol for Enclosure Air 

Sealing. Western Cooling Efficiency Center, UC Davis Building Industry Research Alliance for 

the U.S. Department of Energy Building America Program. DOE/GO-102012-3515. 

https://www.nrel.gov/docs/fy12osti/54046.pdf

 
DOE/GO-102020-5475 • December 2020

For more information, visit: buildingamerica.gov