Measure Guideline: 

Installing Rigid Foam 

Insulation on the Interior 

of Existing Brick Walls

H. Natarajan, S. Klocke, and S. Puttagunta

Consortium for Advanced Residential Buildings 

(CARB)

June 2012 
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iii

Measure Guideline: Installing Rigid Foam Insulation on the 

Interior of Existing Brick Walls

Prepared for: 

Building America

Building Technologies Program

Office of Energy Efficiency and Renewable Energy 

U.S. Department of Energy 

Prepared by:

Hariharan Natarajan, Steve Klocke, and Srikanth Puttagunta

Steven Winter Associates, Inc.

of the 

Consortium for Advanced Residential Buildings (CARB)

61 Washington Street

Norwalk, CT 06854

NREL Technical Monitor: Cheryn Engebrecht 

Prepared under Subcontract No. KNDJ-0-40342-02

June 2012
iv

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v

Contents

List of Figures ........................................................................................................................................... vii

List of Tables ............................................................................................................................................. vii

Definitions................................................................................................................................................. viii

Foreword..................................................................................................................................................... ix

Abstract....................................................................................................................................................... ix

Acknowledgements ................................................................................................................................... ix

Progression Summary................................................................................................................................ x

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

1.1 Methods of Insulating Existing Brick Masonry Buildings..................................................1

1.1.1 Stud Frame and Fibrous Batt Insulation ..................................................................2

1.1.2 Spray Polyurethane Foam Insulation.......................................................................2

1.1.3 Rigid Extruded Polystyrene (XPS) Board Insulation ..............................................2

1.1.4 Alternative Rigid Board Insulation Strategies.........................................................3

1.2 Code Compliance.................................................................................................................3

2 Cost and Performance ......................................................................................................................... 6

2.1 Energy Savings ....................................................................................................................6

2.2 Capital Costs........................................................................................................................7

2.3 Indirect and Non-Energy Benefits.......................................................................................7

2.3.1 Comfort....................................................................................................................7

2.3.2 Indoor Air Quality....................................................................................................7

3 Overview of the Materials Utilized in the Installation of Insulation................................................. 9

3.1 Extruded Polystyrene (XPS) Rigid Insulation Board ..........................................................9

3.2 Foam Construction Adhesive and Applicator Gun..............................................................9

3.3 Low-expanding Foam Sealant and Applicator Gun...........................................................10

3.4 Masonry Anchors...............................................................................................................10

3.5 Colorless Water-Impermeable Coatings for Brick Masonry .............................................10

3.6 Polyurethane Caulk............................................................................................................11

4 XPS (Extruded Polystyrene) Board Installation Procedure ........................................................... 12

4.1 Preparing the Wall .............................................................................................................12

4.1.1 Inspection of the Wall to be Insulated ...................................................................12

4.1.2 Rectification of Defects in Wall to be Insulated....................................................13

4.1.3 Cleaning the Wall ..................................................................................................14

4.2 Installing the XPS Rigid insulation....................................................................................15

4.2.1 Adhering the XPS Rigid Insulation to the Wall.....................................................15

4.2.2 Sealing the Joints and Seams.................................................................................16

4.3 Joists, Sub Floors and Windows........................................................................................16

4.3.1 Where the Insulation Meets the Joists ...................................................................16

4.3.2 Where the Insulation Meets the Sub-floor.............................................................17

4.3.3 Where the Insulation Meets a Window..................................................................17

4.3.4 Where the Insulation Meets an Existing Window .................................................18

4.4 Framing the Stud Wall and Finishing ................................................................................19

4.4.1 Framing Stud Walls After Insulation is Installed ..................................................19

4.4.2 Installing Insulation Behind Existing Stud Wall ...................................................19

4.5 Combustion Safety Testing................................................................................................20

4.5.1 Measure Carbon Monoxide (CO) Concentrations.................................................20

4.5.2 Spillage Tests.........................................................................................................20

4.5.3 Measure Draft ........................................................................................................21
vi

4.5.4 Worst Case Depressurization.................................................................................21

4.5.5 Remedies for Combustion Problems .....................................................................22

Appendix A: Measure Implementation Checklist................................................................................... 23

References................................................................................................................................................. 27
vii

List of Figures

Figure 1. Stud frame and fibrous batt insulation..................................................................................... 2

Figure 2. Framed Stud wall spaced away from brick and polyurethane spray foam insulation......... 2

Figure 3. Stud frame and 2" XPS rigid insulation.................................................................................... 3

Figure 4. Screen shot of eQuest model .................................................................................................... 6

Figure 5. XPS used by Chesapeake Habitat for Humanity...................................................................... 9

Figure 6. Low-expanding foam sealant and applicator......................................................................... 10

Figure 7. Heavily deteriorated brick wall ................................................................................................ 12

Figure 8. Knock off all debris, nails and plaster from wall ................................................................... 14

Figure 9. Example of wall ready for insulation....................................................................................... 14

Figure 10. Adhesive application pattern................................................................................................. 15

Figure 11. Bracing insulation on opposite walls ................................................................................... 15

Figure 12. Board bracing pattern ............................................................................................................ 15

Figure 13. Tape over seams less than 1/8" wide ................................................................................... 16

Figure 14. Use foam to seal all seams greater than 1/8" wide ............................................................. 16

Figure 15. Seal all penetrations through the rigid board with foam .................................................... 16

Figure 16. Install insulation from below ................................................................................................. 17

Figure 17. Seal all seams with low-expanding foam ............................................................................. 17

Figure 18. Rigid insulation extends past the sub-floor when installed from above .......................... 17

Figure 19. Installing a window after installing insulation and flashing. XPS insulation was placed 

between the window buck and the interior jamb extension (not yet installed) of this modular 

home. ................................................................................................................................................... 17

Figure 20. Insulating around an existing window.................................................................................. 18

Figure 21. Slide insulation in behind existing stud wall ....................................................................... 19

Figure 22. Spillage testing of an atmospherically vented, natural gas water heater......................... 20

Unless otherwise noted, all figures were created by CARB.

List of Tables

Table 1. Masonry Wall Insulation Requirements from 2009 IECC (Table 402.1.1)................................ 3

Table 2. Sample Insulation Strategy to Meet 2009 IECC (Table 402.1.1) Requirements...................... 4

Table 3. Masonry Wall Assembly Equivalent U-Value Requirements from 2009 IECC (Table 402.1.3) 

When More Than Half the Insulation is on the Interior..................................................................... 4

Table 4. Modeled Savings from the Installation of Insulation for A 7,600 sq.ft. Multifamily Building 6

Table 5. Cost Range (Labor and Materials) and Simple Payback Period for Interior Insulating of 

8,672 sq.ft. of Brick Walls .................................................................................................................... 7

Table 6. Exposure Limits for Carbon Monoxide (CO) ........................................................................... 20

Table 7. Typical Draft Requirements for Combustion Equipment from BPI’s “Technical Standard 

for the Building Performance Professional” ................................................................................... 21

Table 8. BPI’s CO Action Levels.............................................................................................................. 21

Unless otherwise noted, all figures were created by CARB.
viii

Definitions

ASHRAE American Society of Heating, Refrigerating and AirConditioning Engineers

ASTM American Society for Testing and Materials

BIA The Brick Industry Association.

BLS Bureau of Labor Statistics.

BPI Building Performance Institute

EPA US. Environmental Protection Agency

HfH Habitat for Humanity

HVAC Heating, Ventilating, and Air Conditioning

IBC International Building Code

IECC International Energy Conservation Code

IRC International Residential Code

MSDS Material Safety Data Sheet

NREL National Renewable Energy Laboratory

UL Underwriters Laboratories, Inc.
ix

Foreword

The purpose of this document is to provide information on an effective method to insulate the 

interior of existing brick masonry walls with extruded polystyrene (XPS) insulation board. The 

document outlines step-by-step design and installation procedures while explaining the benefits 

and tradeoffs where applicable.

The authors intend that this document be useful to a varied audience that includes builders, 

remodelers, contractors and homeowners. Whenever a procedure requires specialized equipment 

or expertise, it is recommended those procedures be performed by persons qualified to do so, and

possessing the necessary experience.

Throughout this document, the Consortium for Advanced Residential Buildings (CARB) team

has included images and examples gained from working with various Habitat for Humanity 

(HfH) affiliates on multiple brick masonry retrofits. Though the procedures listed within this 

document have been selected with an eye toward the ease of execution by volunteers, typical of 

HfH construction, the concepts and methods discussed within this report are useful for anyone 

who intends to install rigid insulation on brick masonry walls. The primary goals for the methods 

described in this measure guideline are lowering the costs of execution and operation when 

retrofitting brick buildings, while maintaining or enhancing the overall safety, comfort, and 

durability. 

Abstract

Rigid XPS foam board insulation is an easy-to-install and cost-effective solution when insulating 

the interior of brick masonry walls. When done correctly, with the boards secured flush against 

the brick wall, and the seams properly sealed and taped, the assembly acts as an air and water 

barrier. The boards can be adhered to the wall using both adhesives and/or masonry screws, and 

the cavities in the studded wall can be filled with extra insulation if required to meet code. Since 

the studs are never in direct contact with the brick wall, thermal bridging is minimized. 

The procedure to install XPS insulation requires very little expertise and may be performed by 

homeowners and DIYers at low cost if existing conditions are ideal. If the existing brick shows 

signs of moisture or water intrusion, a qualified contractor should be used to rectify the brick 

assembly prior to insulating. 

As an overall insulation strategy, rigid XPS board insulation is an attractive choice because of 

the low first costs, the ease of installation and the relatively significant energy savings accrued, 

when installed correctly. The payback period is reasonable, and the capital cost and the payback 

period may be minimized by subsidies and incentives provided by state/federal agencies and 

utility companies.

Acknowledgements

The authors would like to acknowledge the funding and support of the U.S. Department of 

Energy’s Building America Program. This guide is the product of a collaborative effort. Special 

thanks to David Lee of the U.S. Department of Energy, Ren Anderson and Cheryn Engebrecht of 

the National Renewable Energy Laboratory, Matt Metzger of Habitat for Humanity of the 

Chesapeake, and Bill Bogdon of Habitat for Humanity NYC. 
x

Progression Summary

Yes?

Wall Studded?

No?

Cut Insulation into pieces 

and slide behind studs or 

consider spray foam

Check wall for –

• Cracked, Loose or Spalled 

bricks

• Deteriorated Mortar 

joints/Sealants

• Efflorescence

• Mold

• Lead paint

Yes?

No?

Clean Wall

Rectify

Moisture Problems?

No?

Yes?

Apply water 

barrier/brick sealant

Install Insulation

Tape and Seal
1 

1 Introduction 

Most of the current stock of load-bearing brick masonry 

buildings were built in the first half of the last century, 

for reasons ranging from the cost effectiveness to the 

durability of brick as a material. Much of this stock, 

when the owners choose to retrofit, upgrade, or convert, 

must be brought up to compliance with the currently 

enforced local building code. Many renovations of 

existing brick residential buildings are also being 

undertaken to meet compliance with green building 

programs. Regardless of the reason, retrofits are on the 

increase, and proper guidance is needed to help these 

projects achieve their goals, which generally align with 

the Building America Program’s goal of reducing home 

energy use by 30%-50% (compared to pre-retrofit 

conditions for existing homes). Insulating these 

buildings is a key step towards the achievement of these 

objectives and a critical component of increasing home 

energy performance. 

1.1 Methods of Insulating Existing Brick 

Masonry Buildings 

Structures may be insulated from either the inside or the outside. Insulating from the outside 

generally results in greater durability (existing structure is protected) and higher airtightness 

(with a continuous exterior air barrier). However, this is not usually undertaken in brick 

structures as it tends to obscure the brick façade, which is a prime aesthetic concern, as well as a 

preservation requirement, if the building in question is a historic structure. A few different 

methods of varying effectiveness are commonly employed to insulate brick masonry structures 

from the inside. 

By insulating the interior, the bricks will be exposed to harsher conditions (i.e. colder 

temperatures), which increases freeze-thaw potential and reduces drying potential. Therefore, for 

any interior insulation method, the exterior brick needs to be fully tuckpointed and an 

appropriate water drainage strategy for the load bearing brick walls is critical to prevent 

water/moisture from penetrating through the brick. If effective exterior water control and 

shedding cannot be properly established, insulating the interior surface of the brick wall 

should not be attempted. For strategies to establish exterior water control and shedding, refer to 

the following Building America report: “Measure Guideline: Internal Insulation of Masonry 

Walls”. 

Addition of Insulation 

When the addition of insulation is planned 

as part of a project, the following resources 

may be helpful: 

• International Code Council (ICC) 

International Building Code (IBC), 2009 

and 2012

• International Code Council (ICC) 

International Energy Conservation Code 

(IECC), 2009.

• Midwest Insulation Contractors 

Association (MICA) Standards Manual 

7th Edition, 2011

• Insulating Solid Masonry Walls: 

http://www.cebq.org/documents/Insulatin

gsolidmasonrywalls-BEF_000.pdf 

• Interior Insulation Retrofits of Load 

Bearing Masonry Walls in Cold 

Climates: 

http://www.buildingscience.com/docume

nts/digests/bsd-114-interior-insulationretrofits-of-load-bearing-masonry-wallsin-cold-climates 
2

1.1.1 Stud Frame and Fibrous Batt Insulation

This is a very common, yet problematic 

insulation method, where a steel or 

wood stud wall is framed against the 

brick masonry and then filled with 

fiberglass batt insulation and finished 

with drywall. The primary issue with 

this type of installation is that there is a 

high probability of condensation and 

dampness in the fibrous batt, potentially 

leading to mold growth, and other 

health hazards. This method is not 

recommended under any 

circumstance.

1.1.2 Spray Polyurethane Foam Insulation

In this strategy, closed-cell polyurethane foam 

is sprayed directly on to the brick masonry. 

This is the most effective, though costly, 

method for insulating the interior of brick 

walls. Framing should be held back an inch or 

two from the masonry wall in order for the 

foam to adhere directly to the masonry and 

reduce thermal bridging. This whole assembly 

is finished with drywall to the face of the 

studs. Closed-cell spray polyurethane foam 

forms a very effective air and water barrier, 

and this method of insulation provides 

excellent airtightness to the insulated portion 

of the envelope. The procedure requires 

expertise and certain specialized tools and 

equipment, and is usually contracted to 

specialists.

1.1.3 Rigid Extruded Polystyrene (XPS) Board Insulation

This method is relatively easy to implement and consists of rigid foam insulation board directly 

adhered to the masonry wall, finished off by studs and drywall. When installed correctly, the 

taped and sealed foam is an effective air barrier.

Two-inch XPS that is rated for moist or below grade applications is recommended in colder 

climates (Climate Zone 4 and higher), as it is a more durable product. If additional insulation is 

required, the cavities in the stud wall may be filled with fibrous insulation as illustrated later in 

this document. The application of a liquid-applied air barrier to the inside of the masonry before 

the installation of insulation can be an advantageous back-up measure.

Figure 1. Stud frame and fibrous batt insulation

Figure 2. Framed Stud wall spaced away from 

brick and polyurethane spray foam insulation
3

Untreated brick has measurable air leakage, therefore, 

for this strategy to be successful, the interior brick 

surface needs to be even to allow for complete and 

uniform adhesion of the XPS boards to the brick. If the 

interior wall surface is uneven, it is recommended that a 

liquid-applied air barrier be applied prior to the XPS, or 

closed-cell spray polyurethane foam (as discussed in 

Section 1.1.2) be applied instead.

This method of insulation has been selected for this 

measure guideline due to its cost effectiveness, and will 

be dealt with exclusively in the rest of this document.

1.1.4 Alternative Rigid Board Insulation Strategies

Two other materials that are often used for insulating walls include:

1. Rigid Expanded Polystyrene (EPS) Board Insulation – Also known as bead-board, 

this is the most inexpensive form of rigid insulation available, but is not as suitable as 

XPS for insulation purposes as it is deficient in a few key areas: EPS has a lower R-value 

per actual inch of thickness (ranges from R-3.5 to R-4 per inch), is weaker and more 

prone to damage while handling, and is the most vapor-permeable type of rigid foam.

Rigid EPS is not recommended as a material to insulate the interior of brick masonry 

walls.

2. Polyisocyanurate (Polyiso) Board Insulation – Polyiso boards are polyurethane boards 

that possess improved strength, thermal resistance and moisture-retardant properties over 

both EPS and XPS insulation boards. Polyiso boards are usually available foil-faced 

(with aluminum) and show an R-value of ranging from R-6 to R-7 per inch. They are 

typically the most expensive of the rigid insulation materials available, but prices 

fluctuate, so this can be a viable alternative based on local pricing at the time of 

construction.

1.2 Code Compliance

The 2009 International Energy Conservation Code (IECC) provides minimum insulation 

requirements for masonry walls that vary across geographically differentiated climate zones

(IECC, 2009).

Table 1. Masonry Wall Insulation Requirements from 2009 IECC (Table 402.1.1) 

Climate Zone Mass Wall Insulation R-Value

1 3 exterior / 4 interior

2 4 exterior / 6 interior

3 5 exterior / 8 interior

4 except Marine 5 exterior /10 interior

5 and Marine 4 13 exterior /17 interior

6 15 exterior /19 interior

7 and 8 19 exterior /21 interior

(The R-value after the slash applies when more than half of the insulation is on the interior of the mass wall – it is 

the minimum R-value applicable to all cases in this document)

Figure 3. Stud frame and 2" XPS rigid 

insulation
4

If retrofitting a brick building that needs to comply with the insulation requirements of 

the 2009 IECC, the climate zone appropriate to the location of the structure must be 

determined, and then the applicable R-value from Table 1 will dictate the level of

insulation needed for the building.

If using rigid foam board insulation, meeting code can be accomplished with various 

thicknesses of XPS board, which can then be supplemented with other forms of insulation 

as required by the specific climate zone. Minimum thicknesses listed in the table below 

may not be available from all manufacturers; the table represents just one example of 

meeting code requirements using XPS board.

Table 2. Sample Insulation Strategy to Meet 2009 IECC (Table 402.1.1) Requirements

Climate Zone Rigid Board Insulation Strategy

1 1” of XPS Board

2 1.25” of XPS Board

3 1.75” of XPS Board

4 except Marine 2” of XPS Board

5 and Marine 4 2” of XPS Board + R-13 Fiberglass Batt

insulation in cavity of studded wall

6 2” of XPS Board + R-13 Fiberglass Batt 

insulation in cavity of studded wall

7 and 8 2” of XPS Board + R-13 Fiberglass Batt 

insulation in cavity of studded wall

Alternatively, rather than following the above prescriptive requirements, Table 402.1.3 of 

IECC 2009, as shown below, can be used. This method would include computing the Uvalue of the proposed insulated brick wall assembly, and ensuring that it does not exceed 

the values from Table 402.1.3. This approach may result in a different insulation 

requirement than if following the prescriptive requirements; however, meeting the 

requirements of either table ensures compliance.

Table 3. Masonry Wall Assembly Equivalent U-Value Requirements from 2009 IECC (Table 402.1.3)

When More Than Half the Insulation is on the Interior

Climate Zone Mass Wall U-Factor

1 0.170

2 0.140

3 0.120

4 except Marine 0.100

5 and Marine 4 0.082

6 0.060

7 and 8 0.057

Typically, the U-Value requirements are less restrictive than the R-Value requirements, for most 

climate zones.
5

Critical Takeaways

• This technique should only be used on sound, clean, and dry brick masonry 

walls.

• Most renovations, remodels, and additions are governed by code, and thus 

these buildings must be brought to compliance.

• In many states, the insulation requirements are determined by Tables 402.1.1 

or 402.1.3 of the International Energy Conservation Code (IECC) 2009. 

• 2” XPS is the recommended starting level for insulating brick walls in Climate 

Zones 4 and higher.
6

2 Cost and Performance

2.1 Energy Savings

We may reasonably assume brick masonry has an R-value of R ~ 1 for every 8” 

thickness (BIA,1997). Due to the relatively low insulating property of brick masonry, the 

addition of 2” of XPS board (an insulation value of R-10) can dramatically increase the 

performance of the building. To demonstrate the energy savings of this insulation, CARB 

constructed a whole building energy model in eQuest v3-64 energy modeling software, 

and simulated the electricity and natural gas consumption before and after the addition of 

insulation for a period of one year. eQuest was used, since the BA preferred software, 

BEopt, does not possess the ability to model structural brick buildings.

The building modeled was a 7,600 sq.ft. multifamily building, with eight apartments of 

approximately 950 sq.ft. each. The total area of wall covered by the new insulation was 

8,672 sq.ft. The modeled building was located in New York City, in Climate Zone 4.

Figure 4. Screen shot of eQuest model

Significant savings were realized in heating bills after the installation of rigid XPS insulation. 

The energy and fuel consumption of the modeled building, both before and after the installation 

of insulation, is shown in Table 4, where reductions of 1% in the electricity consumption and 

13% in gas consumption over a period of one year for the entire building were predicted. The 

simulated utility cost savings were about $388 annually for electricity (cooling) and $1,686 

annually for gas (heating), a combined savings of about $2,074 a year. 

Table 4. Modeled Savings from the Installation of Insulation for A 7,600 sq.ft. Multifamily Building

Pre-retrofit 

(No Insulation)

Post-retrofit 

(R-10 XPS)

Annual Savings 

(USD)

Annual Electricity 

Consumption 

(kWh)

52,480 50,450 $388

Annual Gas 

Consumption 

(Therms)

10,564 9,216 $1,686

(Electricity costs were assumed to be $0.191/kWh and gas costs $1.251/therm.)(BLS, 2011)
7

2.2 Capital Costs

The analysis above shows a potential 9% reduction in energy costs from the installation 

of R-10 insulation. This equates to an annual savings of approximately $260/apartment 

unit. Although those savings can be realized using various insulating materials, rigid XPS 

can be a fairly low first-cost strategy during construction or renovation that provides an 

excellent return on investment. NREL’s National Residential Efficiency Measures 

Database provides cost ranges for the installation of rigid foam wall insulation. Though 

estimated for installation on the exterior, the costs are almost identical to interior 

installation situations assuming the interior is already gutted and intended to be finished 

out with framing and drywall. Table 5 summarizes the installed costs for this multifamily 

building and the simple payback for this measure. It should be noted that the 2” of XPS 

has a lower R-value than the other two insulating measures. The reduced potential energy 

savings due to lower R-value is accounted for in the simply payback analysis.

Table 5. Cost Range (Labor and Materials) and Simple Payback Period for Interior Insulating of 

8,672 sq.ft. of Brick Walls

Measure Installation Costs

(Per ft2)

Installed Cost for 

Modeled Building

Simple Payback 

Period (Years)

XPS, 2”, R-10 Range of $0.95 – $1.30 $8,238 – $11,274 4.0 - 5.4

Closed-Cell Spray 

Polyurethane Foam , 

2”, R-12

Range of $1.80 – $2.25 $15,609 - $19,512 7.5 – 9.4

Polyiso, 2”, R-12 Range of $1.10 – $1.50 $9,539 - $13,008 4.5 – 6.3

2.3 Indirect and Non-Energy Benefits

The installation of insulation directly reduces the thermal loads in the building; as a 

result, HVAC systems can be sized smaller to satisfy the new smaller loads. Correctly 

installed rigid insulation is an air barrier, reducing infiltration and also the amount of 

heating and cooling required, further aiding in the downsizing of HVAC equipment. This 

indirect benefit can be realized if HVAC replacements are part of the scope of the retrofit. 

Besides these energy and first cost savings, the potential non-energy benefits from 

installing insulation on the interior of brick masonry walls are improved comfort and 

indoor air quality.

2.3.1 Comfort

Insulated spaces cool and warm faster, and stay cool and warm longer than uninsulated spaces.

Maintaining thermal comfort within the insulated space becomes easier and more straightforward

as drafts are minimized, and finer control over temperature and humidity becomes possible.

2.3.2 Indoor Air Quality

A reduction in infiltration helps maintain air quality in the space, and reduces the chances of 

external contaminants entering the home. However, controlled mechanical ventilation should be 

added to any substantially airtightened building in order to ensure acceptable indoor air quality.
8

Critical Takeaways

• The addition of insulation reduces energy consumption, utility bills, and size of 

HVAC equipment needed, as well as likely increasing comfort and indoor air 

quality.

• In most cases, the installation of rigid insulation has a lower capital cost than 

closed cell spray polyurethane foam insulation.

• The payback period on the installation of rigid insulation is usually very 

reasonable.

• Precaution: When reducing the natural air exchange of a home, there is a 

potential need for mechanical ventilation depending on the level of air 

tightness.

Is mechanical ventilation needed?

Infiltration testing with a blower door should be performed at the completion of the 

energy efficiency measure. Results from this testing should be used to determine if 

additional mechanical ventilation is required according to the ASHRAE 62.2 

ventilation standard.

1. Calculate the required mechanical ventilation rate for the home from 

ASHRAE 62.2. CFMdesign

CFMdesign = 0.01 x FA + 7.5(Nbr + 1)

Where FA = finished floor area and Nbr = # of bedrooms

2. From the infiltration testing, determine the CFM50 number for the building.

3. Use the Sherman-Grimsrud air infiltration model (Sherman M. 

1987. Estimation of Infiltration for Leakage and Climate Indicators. Energy 

and Buildings, 10, p.81.) to estimate infiltration under natural conditions. 

CFMnat (here is a reference for how to determine this value: 

http://www.homeenergy.org/show/article/nav/blowerdoor/id/1015) 

4. Divide CFMnat by conditioned square footage. CFMnat/ft2

5. Is the CFMnat/ft2 value less than 0.02? If yes, use the ASHRAE 62.2 value 

for ventilation. You cannot reduce the mechanical ventilation rate.

6. If the CFMnat/ft2 value is greater than 0.02, perform the following calculation 

to determine how much mechanical ventilation you need.

CFMneeded = CFMdesign – [1/2 x (CFMnat/ft2– 0.02) x FA)
9

3 Overview of the Materials Utilized in the Installation of 

Insulation

3.1 Extruded Polystyrene (XPS) Rigid Insulation Board

Rigid XPS boards for building insulation are typically 

available in 2’x8’ and 4’x8’ sizes, in thicknesses between 

0.5” to 2”. Most codes usually require a thermal ignition 

barrier (2009 IRC Section R316.4) and thus XPS board 

cannot be left exposed indoors except in special cases. The 

boards are usually available with butt or shiplap edges to 

aid in ensuring a tight air-seal during installation.

• R-value: 5 ft2h°F/Btu-in (R-5/inch)

• Air barrier: Yes

• Vapor retarder: Typically Class II (1.2 Perm-inch, 

ASHRAE 1997)

XPS board is commonly used on the outside of residential 

above-grade walls, and on the inside and outside of 

foundation walls.

3.2 Foam Construction Adhesive and 

Applicator Gun

Foam construction adhesives used to adhere the foam board to the brick masonry, are 

usually aerosol-propelled, moisture-curing polyurethane adhesives. They can be used on 

plywood, lumber, OSB, fiberglass, foam board, and most other construction materials, 

and are applied using a special purpose gun applicator. The advantages of using foam 

adhesive over traditional construction adhesive are:

• Low cost – One can of foam adhesive is usually the equivalent of 10 to 20 quart 

tubes of standard construction adhesive, depending on bead thickness. Overall, 

the cost of the can, gun and cleaner are cheaper than the equivalent amount of 

quart tubes of construction adhesive.

• Efficient application – The use of the gun allows for accurate and efficient 

application of the foam to the board. The gun needs to be cleaned regularly and 

stored with the cleaner can between uses to prevent clogging.

When working with foam sealants and foam adhesives, recognize that some of the sealant 

and adhesive materials can be hazardous if not handled properly. Refer to the Material 

Safety Data Sheets (MSDS) for all chemical products used. Use appropriate personal

protective equipment including respirators, safety glasses, kneepads, and disposable 

protective clothing as appropriate.

Figure 5. XPS used by Chesapeake 

Habitat for Humanity
10

3.3 Low-expanding Foam Sealant and Applicator Gun

Similar to foam construction adhesives, low-expanding foam sealants are usually aerosolpropelled, moisture-curing urethane foams that are used to air-seal insulation board 

joints, edges and gaps. The foam expands in place and bonds to seal and stop the passage 

of air, gases and water. The foam can be used on plywood, 

lumber, OSB, fiberglass, foam board and most other 

construction materials, and is applied using a special purpose 

gun applicator. The advantages of using low-expanding foam 

sealant are:

• Low Cost – One 12 ounce can of foam sealant usually 

provides the equivalent of 1,200 linear feet of a 1⁄2” 

bead of sealant.

• More Efficient Application – The use of the gun 

allows more accurate and efficient application of the 

foam to the board, and reduces waste from storage and 

transport. The gun needs to be cleaned regularly and 

stored with the cleaner can on between uses to prevent 

clogging.

Once applied, the foam is tack-free in 10 minutes and trimmable (for finishing purposes) 

in about 30 minutes. The cured foam resists age-hardening, solvents, and water, but will 

deteriorate if exposed to direct sunlight.

3.4 Masonry Anchors

Masonry anchors are usually screw-type devices used to secure different materials and 

components to brick and concrete. There are many kinds of masonry anchors, but the 

ones most applicable to the installation of rigid insulation on the 

inside of brick masonry are concrete screws. These are basically 

stainless steel or coated screws that cut their own thread into the 

brick, when driven into the masonry. They are highly resistant to 

rust and provide excellent holding to the brick. When choosing 

screw lengths, make sure that the screw embeds itself at least 1”

into the masonry after going through all the components that 

need to be adhered to the wall.

Length of screw required = Thickness of material being anchored + 1”~1.5”

(Embedment Depth)

3.5 Colorless Water-Impermeable Coatings for Brick Masonry

Colorless coatings are used on brick masonry to create vapor-permeable but air and water 

resistant barriers. These applied barriers must be used after a thorough inspection of the 

cleaned brick surface for water penetration issues.

Colorless coatings for brick are of two types:

• Film-forming coatings – These form a film on the surface of the brick and help prevent 

leaks. They are available as acrylics, stearates, mineral gum waxes, and urethanes.

Figure 6. Low-expanding 

foam sealant and applicator

Helpful Tip

Be sure to use the correct 

drill bit size specified by 

the screw manufacturer 

when screwing masonry 

screws into walls.
11

• Penetrants – These penetrate the surface of the brick to depths up to 3/8”, and prevent 

water penetration by changing the capillary force of the brick surface from positive 

(suction) to negative (repulsion).

Colorless coatings of both kinds are rendered ineffective if there are cracks present in the brick 

that are greater than 0.02” wide. Therefore, the brick MUST be inspected and the cracks 

remedied before the application of the coatings.

3.6 Polyurethane Caulk

Tube-applied polyurethane caulk is an acceptable alternative to the gun-propelled 

polyurethane foam adhesive for use on rigid foam board. Polyurethane caulk adheres well 

to most substrates, and cures relatively quickly.
12

4 XPS (Extruded Polystyrene) Board Installation Procedure

The following instructions set out general procedures for the installation of XPS rigid insulation 

on the interior of brick masonry walls. Keep in mind the following:

• When using specialized equipment such as the gun applicator for the adhesive foam, 

follow all manufacturer-supplied instructions and precautionary measures. 

• Use the appropriate safety equipment, such as gloves and goggles, when performing 

certain procedures, such as the application of adhesive or foam sealant.

• Refer to Appendix A for an installation checklist to follow in the field.

4.1 Preparing the Wall

There are three stages to the preparation of the wall for the installation of rigid insulation—

inspection, rectification and cleaning.

4.1.1 Inspection of the Wall to be Insulated

Before the installation of insulation, the brick masonry wall must be inspected for the following

defective conditions (BIA, 2005). If any are found to exist, DO NOT proceed with the 

installation of insulation until the defective conditions are rectified. All these conditions may 

be exacerbated by the addition of insulation, and the potential for health and safety hazards may 

be greatly increased.

• Cracked bricks

• Loose bricks

• Spalled bricks

• Hairline cracks in mortar

• Deteriorated mortar joints

• Deteriorated or torn sealants

• Out-of-plumb (non-vertical, sagging wall)

• Efflorescence (salts left on brick by 

evaporation – indicative of water path 

through brick)

• Staining

• Water penetration (check for dampness on 

the interior)

• Mold

• Lead paint.

Figure 7. Heavily deteriorated brick wall
13

4.1.2 Rectification of Defects in Wall to be Insulated

The following are general guidelines for the determination and 

correction of existing defects in the brick wall prior to the 

application of insulation. Again, insulation MUST NOT be 

installed unless these defects are corrected. As many of these 

repairs are beyond the scope of this document, references have 

been provided for those interested in a deeper investigation of 

these topics:

1. Cracked, loose and spalled bricks (BIA, 2005) – These 

bricks must be replaced. The bricks to be replaced must 

be cut out without affecting the bricks around them.

The wall must be dampened, and then the replacement 

bricks must be ‘buttered’ with mortar and then centered 

in the cavities, also ‘buttered’ with mortar. After the 

mortar is ‘thumbprint’ hard, the joints can be tooled as 

desired.

2. Hairline cracks in mortar/deteriorated mortar joints

(BIA, 2005)– The damaged mortar must be removed, 

and the joints must be repointed. This is specialized 

work and it is recommended that an expert be 

contracted to perform this work, especially on historic 

masonry buildings (Robert and Speweik, 1998). 

Repointing with incorrectly selected mortar may result 

in damage to the masonry materials (NPS, 1998).

3. Deteriorated/torn sealants (BIA, 2006) – Remove 

deteriorated sealants without damaging adjacent 

brickwork, prime, and reseal. For further information, 

see ASTM C 1193, Guide for Use of Joint Sealants.

4. Efflorescence and staining (BIA, 2006) – Repair any 

leaks before cleaning efflorescence (usually washing 

with water after repair mortar has dried, and then 

rubbing with a stiff brush.) (Merrigan, 1986) Staining may be removed by a poultice, 

after determining the cause of the stain. If the stain damage is only cosmetic, it may 

be ignored as the insulation will be installed over the brickwork and will completely 

obscure the stain from view.

5. Water penetration – Check for dampness on the wall to be insulated (interior). Any 

dampness is a sign of more serious problems and indicative of moisture transport 

across the wall (Straube et al 2011), from the outside to the inside. Allow the brick to 

dry out, address any bulk water penetration issues, and then apply a waterproof 

membrane or brick sealant. Allow to dry/cure before installing insulation. Repeat 

check after cleaning wall.

6. Mold – If less than 1 sq.ft. of mold is found on the surface of the wall, simple 

remedies are available. Soak the wall with water and then spray the mold directly 

with a solution of bleach and water. Then brush out with a stiff brush. Repeat until no 

more mold is visible. Once all mold is gone, wash surface with warm water, then 

spray and soak surface with vinegar to kill subsurface mold. Allow the affected part 

Lead

Lead poisoning can cause 

nervous system damage, 

stunted growth, liver damage 

and delayed development in 

children. The most common 

form of exposure to lead is 

from the lead dust in paint. 

Children are particularly at 

risk, as lead paint tastes 

sweet, and they are thus 

more prone to ingesting it.

Mold

Mold spores can develop on 

porous surfaces, in the 

presence of food (like wood 

and paper), oxygen, 

moderate temperatures 

(typically over 65°F, but if 

enough water is present, 

down to 40°F), and sufficient 

water. 
14

of the wall to dry completely before installing insulation. Do not forget to use 

facemasks and gloves when cleaning out mold. The presence of mold indicates the 

existence of a moisture problem, which must be investigated after the mold has been 

removed. If the cause of the mold cannot be identified and/or if the mold growth is 

greater than one square foot, it is recommended to hire a mold consultant specializing 

in building assessments to evaluate the entire home. For more detail on mold causes 

and remediation see “Preventing Mold/Moisture Problems” (CARB)

7. Lead paint – This is a serious health hazard usually found in historic homes and 

homes of a certain vintage. Lead paint removal requires specialized equipment and 

expertise and should not be performed by volunteers. If lead paint is suspected, work 

must not continue until the situation is remedied by specialists. Refer to EPA’s 

website on lead for further detail (www.epa.gov/lead).

In addition to evaluating the condition of the walls prior to retrofit, check to see if any 

combustion equipment exists in the space to be insulated that does not source its combustion air 

from the outside. If atmospheric combustion appliances exist within the space, combustion safety 

testing is required (see Section 4.5). If combustion appliances are being replaced, specify sealed

combustion equipment.

4.1.3 Cleaning the Wall

Not all brick interiors are exposed, and most projects will 

encounter walls covered in plaster or some other material. To 

ensure proper adhesion of insulation to the wall, and to prevent 

any air gaps that may occur and create convective loops, the 

wall must be cleaned of all debris, nails and plaster. The wall 

does not have to be perfectly smooth, but smooth enough that 

no significant air gaps are formed between the insulation and 

the wall that can harbor convective loops that transport 

moisture.

1. Knock off all nails, debris and plaster with a 

hammer and chisel (if required).

2. If a large area of the wall is covered by plaster that 

cannot be removed by hand, then consider the 

removal of plaster by soaking, scraping and 

pressure-washing (above 1,500 psi). The use of 

muriatic acid solutions are not recommended as 

they tend to damage and discolor the brick, an 

important consideration when dealing with historic 

buildings. Both these methods are a last resort, and 

should only be performed by experts with the 

necessary equipment.

3. Allow wall to dry completely before proceeding.

4. Inspect walls again after cleaning, following steps in 

4.1.2.

Figure 8. Knock off all debris, 

nails and plaster from wall

Figure 9. Example of wall ready 

for insulation
15

4.2 Installing the XPS Rigid insulation

The installation of the XPS board occurs in a couple of steps: adhering the board to the 

wall, and sealing or taping the seams.

4.2.1 Adhering the XPS Rigid Insulation to the Wall

When possible, use the entire 2’x8’ or 4’x8’ sheet of rigid insulation.

1. Prepare the applicator gun and adhesive as per the manufacturer’s instructions.

2. Apply a 1⁄2” bead of foam along the perimeter of the board and as an ‘X’ across the 

center. A serpentine application 

across the board is also an 

acceptable alternative to the 

‘X’.

3. Apply the rigid insulation to

the predetermined wall surface.

Make sure to apply continuous 

pressure to the rigid board.

Moving the board repeatedly 

will reduce the adhesion of the 

board to the wall.

4. Place a 2x4 brace against the 

seam of the rigid insulation 

boards and secure until the binder 

is fully cured. At the Habitat for Humanity projects, extension poles braced against an 

opposing wall were used to hold the wood and rigid insulation in place. The narrow 

configuration of these rowhouses allowed for this bracing method. 

5. When installing insulation where no stud wall is intended, or where there are 

concerns about the adhesion of the board to the wall, it is advisable to use masonry 

screws and EIFS washers or IDP insulation anchors to fasten the insulation directly to 

the masonry wall.

Figure 10. Adhesive application pattern

Figure 11. Bracing insulation on 

opposite walls

Figure 12. Board bracing pattern
16

4.2.2 Sealing the Joints and Seams

Once all the rigid insulation board has adhered to the wall

(after 10 minutes or so of continuous applied pressure), the 

joints and seams must be sealed to create an effective,

continuous air-barrier.

1. Tape over all seams that are LESS that 1/8” wide.

Ideally, all the joints should be as tightly butted as 

possible.

2. Prepare low-expanding foam sealant and 

applicator gun as per the manufacturer’s 

instructions.

3. Fill all cracks, joints and seams GREATER than 

1/8” wide with low-expanding foam. Use foam to 

seal all penetrations through the insulation board.

4. Allow foam to cure. Foam is usually tack-free in 

15 minutes and completely cured in 8 hours.

4.3 Joists, Sub Floors and Windows

Insulating around joist, subfloors, and windows is a 

relatively straightforward task, with the only extra work 

required being the cutting of the XPS board.

4.3.1 Where the Insulation Meets the Joists

1. Measure around the joists and cut the 

insulation board to fit.

2. Apply adhesive to the pieces of insulation.

3. Slide insulation pieces into place and allow to 

adhere to wall.

4. Seal all gaps with low-expanding foam.

Figure 13. Tape over seams 

less than 1/8" wide

Figure 14. Use foam to seal all seams 

greater than 1/8" wide

Figure 15. Seal all penetrations through 

the rigid board with foam

How to cut XPS board

1. Score the insulation on both 

sides with a utility knife

2. Snap off the scored piece
17

4.3.2 Where the Insulation Meets the Sub-floor

The process for installing the insulation where the sub-floor is 

cut away from the brick wall is almost identical to the process 

for insulating around joists.

1. Measure around the joists and cut the insulation 

board to fit.

2. Apply adhesive to the pieces of insulation.

3. Slide insulation pieces into place from above/below

and allow to adhere to wall.

4. Seal all gaps with low-expanding foam.

For multifamily construction, the requirements for rated assemblies between floors preclude this 

process. Typically, some type of wood or gypsum board will be used to terminate the wall 

assembly between floors.

4.3.3 Where the Insulation Meets a Window 

When insulating walls in which the window is being 

replaced, follow these steps:

1. Ensure proper window flashing is 

installed and window sill is properly 

pitched.

2. Measure around the window opening 

and cut insulation board to fit. 

3. Install the insulation.

4. Seal the rigid insulation to the window

buck with low-expanding foam sealant 

or caulk.

Figure 18. Rigid insulation 

extends past the sub-floor 

when installed from above

Figure 16. Install insulation from below Figure 17. Seal all seams with low-expanding foam

Figure 19. Installing a window after 

installing insulation and flashing. XPS 

insulation was placed between the window 

buck and the interior jamb extension (not 

yet installed) of this modular home.
18

5. Install the window.

6. Seal the gap between the buck and window jamb with low-expanding foam sealant or 

caulk.

4.3.4 Where the Insulation Meets an Existing Window

When insulating walls that contain existing windows, it is important to keep in mind that the 

proper window drainage must be addressed first. This may require windows to be temporarily 

pulled/removed to allow for the installation of pan flashing.

1. Seal any existing small gaps between the brick and window buck with low-expanding 

foam sealant or caulk.

2. Cut and install interior rigid insulation so that it covers the existing window buck.

3. The interior stud wall should be framed flush to the rigid insulation edge (flush with 

buck).

4. Install an interior jamb extension to cover the exposed edge of the rigid insulation and 

stud framing. The jambs of the windows/doors should be extended to be flush with 

the interior face of the drywall.

5. Install drywall so that it butts up against the interior jamb extension. Seal gap with 

caulk.

6. Install window trim to cover butt joint of jamb extension to drywall.

Figure 20. Insulating around an existing window
19

4.4 Framing the Stud Wall and Finishing

To be compliant with code, and to negate the risk of a fire (polystyrene is flammable), the 

insulation cannot be exposed to interior conditions except in special cases (2009 IRC Section 

R316.4). Insulated walls are usually finished with a stud frame and drywall on the inside, which 

provides the homeowner or builder/contractor with the advantage of wall cavity space where 

further insulation can be installed if necessary. In special cases, insulation is finished by directly 

laminating the drywall on to it and skipping the framed stud wall, in cases like insulating around 

an existing fireplace.

4.4.1 Framing Stud Walls After Insulation is Installed

1. When studding out the walls, press the wood up against the rigid insulation. If the 

wall is too far out of alignment, place the wall as close as possible while still 

maintaining a straight wall profile.

2. Fill stud wall cavities with insulation if necessary.

3. Install drywall.

4.4.2 Installing Insulation Behind Existing Stud Wall

Rigid insulation can be installed after the walls are studded out, 

though the increased labor and longer install times associated with 

installing rigid XPS insulation behind an existing stud wall may 

decrease its cost effectiveness as a strategy.

1. If a wall has already been studded out, cut pieces of 

rigid insulation to a workable size so that they can be 

slid in behind the stud wall. This is a cumbersome and 

time consuming process, and may negate the costeffectiveness of installing rigid insulation under these

conditions. For conditions involving existing stud 

walls, spray polyurethane foam insulation is a better 

strategy.

2. Fill stud wall cavities with insulation if necessary.

3. Install drywall.

Figure 21. Slide insulation in 

behind existing stud wall

Critical Takeaways

• The key to the success of installing rigid insulation is the proper sealing of all 

joints, seams and cracks - creating a tight air/water barrier.

• The insulation can NEVER be exposed to ambient conditions on the inside. A 

thermal ignition barrier, such as drywall, MUST be installed to be compliant 

with code.
20

4.5 Combustion Safety Testing

It is important to assess combustion appliances in the home and any potential safety issues 

associated with them. Adding rigid insulation in this manner can result in different pressure 

patterns within a home that can potentially alter combustion venting and draft. A brief overview 

of recommended safety precautions is provided here. It may be appropriate to consult more 

detailed program guidelines or to refer to BPI’s “Technical Standards for the Building Analyst 

Professional.”

4.5.1 Measure Carbon Monoxide (CO) Concentrations

Measuring ambient levels of carbon monoxide in the home is simple and can identify potentially 

hazardous situations. If ambient CO levels are extremely high, work should not proceed until the 

problem is corrected. It may also be appropriate to measure CO levels in the flue or exhaust from 

appliances (usually a different instrument is required). If CO concentrations in exhaust are high, 

it may be appropriate to have a qualified contractor adjust or tune the equipment to correct the 

problem.

Table 6. Exposure Limits for Carbon Monoxide (CO)1

Agency / Organization Maximum CO Concentrations

Occupational Safety and Health 

Administration (OSHA)

50 ppm as an 8-hour time-weighted 

average

National Institute for Occupational Safety and 

Health (NIOSH)

35 ppm as an 8-hour time-weighted 

average AND 200 ppm at any time

American Conference of Governmental 

Industrial Hygienists (ACGIH)

25 ppm as an 8-hour time-weighted 

average for a 40-hour work week.

4.5.2 Spillage Tests

“Spillage” is the term used to describe the situation when a proper 

draft is not established in the flue pipe or chimney; the flue gases 

come “spilling” back down the flue and into the house. Spillage 

may be caused by pressure imbalances within the house and/or 

improper venting. Since flue gases can contain significant amounts 

of moisture and carbon monoxide, spillage can result in dangerous 

and unhealthy conditions. 

Check for spillage by turning the appliance on and using a smoke 

stick, glass, or mirror to verify that there is negative draft around 

the draft diverter (i.e. flue gases are flowing up—not down—the 

flue) that is established within one minute of the burner firing. It is 

not unusual for some appliances (especially water heaters) to spill 

temporarily on startup. This is because the chimney needs to heat 

up before a proper draft is established. Spillage that occurs under 

normal building operating conditions should be addressed 

immediately. This is a serious health and safety risk for the 

 

1 http://www.osha.gov/SLTC/healthguidelines/carbonmonoxide/recognition.html

Figure 22. Spillage testing 

of an atmospherically 

vented, natural gas water 

heater
21

occupants. Spillage may also be checked under simulated “worst-case” conditions as described 

in Section 4.5.4 below.

4.5.3 Measure Draft

Draft is measured by taking a pressure measurement in the flue pipe approximately 12” 

downstream of the draft diverter. Draft should be measured under steady state conditions 

(usually after 5-10 minutes of operation). Acceptable draft is dependent on the outside 

temperature and height of the flue stack. Typical ranges are shown in Table 7.

Table 7. Typical Draft Requirements for Combustion Equipment from BPI’s “Technical Standard 

for the Building Performance Professional”

Outdoor Temperature (Tout, °F) Minimum Acceptable Draft (Pa)

<10 -2.5

10-90 (Tout / 40) - 2.75

>90 -0.5

4.5.4 Worst Case Depressurization

It is often recommended that combustion safety tests be 

conducted under “worst case” conditions. Since testing only 

gives us a snapshot of how the system is performing on a 

particular day under the current conditions, it does not 

necessarily assure us that the system might not fail at another 

time under different conditions. Using the worst-case 

approach, contractors are better assured that combustion 

appliance failures will not occur after they leave the house. 

To set up worst case conditions, first identify the combustion 

appliance zone (CAZ) and set up a manometer to measure the 

pressure in the CAZ with reference to (wrt) outside. Make 

changes to the house configuration using the following 

checklist, and check the CAZ pressure wrt outside at each 

step. Keep making changes until you have achieved the 

most negative pressure possible in the CAZ.

Checklist for Establishing Worst-Case Depressurization:

• Turn on exhaust fans (bath fans, range hoods, etc), 

including clothes dryers

• Turn on/off the air handler fan

• Open/close door to the CAZ (in some houses open 

will be worst case, in others the door should be 

closed for worst case)

• Open/close interior doors

Once you have established the worst-case scenario, turn on the combustion appliances, one at a 

time, starting with the smallest. Check each appliance individually for spillage and draft. If more 

Table 8. BPI’s CO Action 

Levels

CO 

Level 

(ppm)

And/Or Spillage and 

Draft

Retrofit 

Action

0-25 And pass proceed

26-100 And pass

recommend 

fix

26-100 And fails 

(worst case)

recommend 

fix

100-400 Or

fails 

(natural 

case)

stop work, 

fix

>400 And pass stop work, 

fix

>400 And fails 

(any case)

shut off fuel, 

fix

Identifying the CAZ

A combustion appliance zone 

is any room/space within a 

home that contains an 

appliance that burns fuel 

(wood, natural gas, propane, 

oil, etc.)
22

than one appliance shares a chimney, also conduct the test with both appliances operating 

simultaneously.

4.5.5 Remedies for Combustion Problems

If combustion problems are identified, they should be 

immediately addressed by a qualified contractor. While safe 

operation can be achieved by providing outdoor air and 

adjusting appliances properly, installing sealed-combustion

appliances is very often the best remedy for providing 

reliable, safe, and efficient space heating and water heating.

Strong consideration should be given to this strategy.

In homes with any combustion appliances, carbon monoxide 

sensors/alarms are required by many codes. These can help 

alert occupants to serious combustion problems.

Minimum single 

opening to outside for 

combustion appliances

Reference: Chapter 24 of 

2009 International Residential 

Code (IRC) for One- and TwoFamily Dwellings; Section 

G2407.6.2
23

Appendix A: Measure Implementation Checklist

The nature and scope of brick masonry wall insulating efforts can vary substantially. Based on 

these guidelines, the checklist below is presented as a potential framework (though not an 

exhaustive resource) for installing rigid insulation on the interior of a brick masonry wall.

1. Inspect the interior of the wall for significant risks. Are any of the following present?

Cracked, Loose and Spalled Bricks YES NO

Cracks/Deterioration in mortar YES NO

Cracks/Deterioration in sealant YES NO

Efflorescence YES NO

Staining YES NO

Mold or Lead paint YES NO

Moisture Problems YES NO

Occupants with health conditions who may be 

sensitive to work being done YES NO

If the answer is YES to any of these or if other serious risks are identified, do not proceed with 

work until the risks have been addressed. If the wall is plastered, REMOVE plaster and inspect 

the wall again.

2. Cleaning the Wall

Clean the wall of all debris, plaster and nails. Then inspect it again.

Is the wall free of debris, plaster and nails? YES NO

Are any of the risk issues from Item 1 present? YES NO

If any risks are present, rectify before proceeding with the installation of insulation.

3. Moisture Penetration and Sealing

Are there cracks in the brick and mortar greater than 0.02” YES NO

Are there any visible signs of moisture penetration? YES NO

• If there are cracks in the brick greater than 0.02”, rectify before proceeding.

• If there are no visible cracks, but evidence of moisture penetration, apply a liquid 

air/water barrier to the surface

• Allow the applied coating to cure as per manufacturer’s instructions.

• If there are no cracks or visible signs of moisture penetration, it is not necessary to apply 

the air/water barrier coating.

Has the air/water barrier coating cured? YES NO
24

4. Installation of Complete Boards of Insulation

• Prepare adhesive gun as per manufacturer’s instructions.

• Dry-fit the insulation to the wall. Use full 4’x8’ sheet as far as possible. Place it flush to 

the floor.

• Apply a 1⁄2” bead of adhesive along the perimeter of the board, and as an ‘X’ across the 

center. 

• Apply the rigid insulation to the 

wall surface.

• Apply continuous pressure for 

about 5 minutes. DO NOT move 

the board around as it will reduce 

the adhesion of the foam adhesive.

• Place a 2x4 brace against the seam 

of the rigid insulation boards. If a 

narrow width, use an extension 

pole to hold the wood and rigid 

insulation in place for at least 5 

minutes. Do both sides of the units 

at the same time as this will speed 

the process up by providing 

support to both pieces of rigid 

insulation. Adhesive Application Pattern

Pole and board bracing pattern

Bracing opposite sides with extension poles
25

Has all the wall area that can be covered with full-size 

boards been covered? YES NO

Have all the installed boards been braced for at least 5 

minutes? YES NO

5. Installation of Cutouts around the Joists and Sub-floor

• Measure joists and sub-floor cutouts. The cutouts should extend at least 6” above the 

ceiling plane and below the floor.

• Cut insulation sheets to fit. (To cut insulation – mark with pen, score with utility knife 

and then snap).

• Apply adhesive as before to insulation sheets.

• Slide sheets to fit into joists from below.

• Slide sheets into gap between sub-floor and wall from above.

• Brace sheets and apply continuous pressure for at least 5 minutes

Have the insulation boards adhered to the wall? YES NO

6. Taping and Sealing Joints

• Prepare foam sealant gun as per manufacturer’s instructions.

• Fill all cracks, seams and joints GREATER than 1/8” wide.

• The following areas should be filled:

o seam between the floor and the rigid insulation

o space between adjoining pieces of rigid insulation

o area around the floor joists

o top edge of rigid insulation that extends into the ceiling area

o overlap of insulation, if plaster cannot be removed

o any other areas where brick is exposed and rigid insulation cannot be utilized.

• Tape over all seams and joints LESS than 1/8” wide

Have all cracks, seams and joints been sealed? YES NO

7. Insulating behind an existing stud wall

Is there an existing stud wall? YES NO

• Cut insulation boards into pieces small enough to slide behind the studs.

• Apply adhesive as before to insulation sheets

• Slide sheets to fit into joists from below.

• Slide sheets into gap between sub-floor and wall from above.

• Brace sheets and apply continuous pressure for at least 5 minutes.

• Tape and seal all cracks, joints and seams.

• Install insulation in stud wall cavity if necessary.

• Install drywall.
26

Have the insulation boards adhered to the wall? YES NO

Have all cracks, seams and joints been sealed? YES NO

8. Framing a stud wall

• Press wood up against rigid insulation.

• If masonry wall is out of alignment, place wall as close to insulation as possible while 

still maintaining a straight profile.

• Install insulation in stud wall cavity if necessary.

• Install drywall.

9. Installing when no stud wall is intended (Like around fireplaces)

• Install insulation as before.

• Use masonry screws to adhere the insulation structurally to the masonry.

• Apply construction adhesive to drywall.

• Laminate drywall directly to insulation.

10. Insulating around a window

Is there an existing window? YES NO

If there is an existing window in the wall:

• Seal any existing small gaps between the brick and window buck with low-expanding 

foam sealant or caulk. 

• Cut and install interior rigid insulation so that it covers the existing window buck.

• The interior stud wall should be framed flush to the rigid insulation edge (flush with 

buck).

• Install an interior jamb extension to cover the exposed edge of the rigid insulation and 

stud framing. The jambs of the windows/doors should be extended to be flush with the 

interior face of the drywall.

• Install drywall so that it butts up against the interior jamb extension. Seal gap with caulk.

• Install window trim to cover butt joint of jamb extension to drywall.

If there is no existing window in the wall:

• Ensure proper window flashing is installed and window sill is properly pitched.

• Measure around the window opening and cut insulation board to fit. 

• Install the insulation.

• Seal the rigid insulation to the window buck with low-expanding foam sealant or caulk.

• Install the window.

• Seal the gap between the buck and window jamb with low-expanding foam sealant or 

caulk.
27

References

ICC (2009). International Energy Conservation Code. Washington, DC: International Code 

Council.

ICC (2009). International Residential Code. Washington, DC: International Code Council.

BIA. (1997)."Technical Notes 4 - Heat Transmission Coefficients of Brick Masonry Walls."

Technical Notes on Brick Construction. Reston, VA: The Brick Industry Association. Accessed 

June 11, 2012: http://www.gobrick.com/Portals/25/docs/Technical%20Notes/TN4.pdf.

Bureau of Labor Statistics, U.S. Department of Labor. (2011). AVERAGE ENERGY PRICES IN 

NEW YORK – NORTHERN NEW JERSEY – FERBRUARY 2012, NYLS-7522. Accessed June 

11, 2012: http://www.bls.gov/ro2/avgengny.pdf.

"Retrofit Measures for Wall Sheathing." National Residential Efficiency Measures Database. 

National Renewable Energy Laboratory, Accessed. December 18, 2011:

http://www.nrel.gov/ap/retrofits/measures.cfm?gId=1&ctId=44

BIA.(2005). "Technical Notes 46 - Maintenance of Brick Masonry." Technical Notes on Brick 

Construction. Reston, VA: The Brick Industry Association. Accessed June 11, 2012:

http://www.gobrick.com/Portals/25/docs/Technical%20Notes/TN46.pdf.

Mack, Robert, and Speweik, John. National Park Service. Technical Preservation 

Services. Preservation Briefs - Repointing Mortar Joints in Historic Masonry Buildings. 1998. 

http://www.nps.gov/hps/tps/briefs/brief02.htm.

BIA. (2005) " Technical Notes 7A -Water Penetration Resistance - Materials." Technical Notes 

on Brick Construction. Reston, VA: The Brick Industry Association. Accessed June 11, 2012:

http://www.gobrick.com/Portals/25/docs/Technical%20Notes/TN7A.pdf

BIA. (2006)" Technical Notes 20 -Cleaning Brickwork." Technical Notes on Brick Construction.

Reston, VA: The Brick Industry Association. Accessed June 11, 2012:

http://www.gobrick.com/Portals/25/docs/Technical%20Notes/TN20.pdf.

Merrigan, M.. "Efflorescence: Cause and Control." The Masonry Society Journal , 1986.

Straube, J.F., Ueno, K., and Schumacher, C.J.. Building Technologies Program, U.S. Department 

of Energy. (2012). Measure Guideline: Internal Insulation of Masonry Walls. (to be published 

summer 2012)

BPI. (2005). Technical Standards for the Building Analyst Professional. Malta, NY: Building 

Performance Institute. Accessed April 8, 2011: http://www.bpi.org/Web Download/BPI 

Standards/Building Analyst Professional_2-28-05nNC-newCO.pdf.

Gromicko, N., London, R., and Shepard, K. “Efflorescence for Inspectors.” Accessed June 11, 

2012: http://www.nachi.org/efflorescence.htm.
28

Mack, R. and Speweik, J. (1998). Repointing Mortar Joints in Historic Masonry Buildings.

National Park Service. Accessed May 7, 2012: 

http://www.nps.gov/history/hps/tps/briefs/brief02.htm. 
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