Measure Guideline:

Wall Air Sealing and Insulation 

Methods in Existing Homes 

An Overview of Opportunity and Process

S. Roberts and R. Stephenson

NAHB Research Center Industry Partnership

September 2012
This report received minimal editorial review at NREL.

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iii

Measure Guideline:

Wall Air Sealing and Insulation Methods in Existing Homes

An Overview of Opportunity and Process

Prepared for: 

Building America

Building Technologies Program

Office of Energy Efficiency and Renewable Energy 

U.S. Department of Energy 

Prepared by: 

The NAHB Research Center Industry Partnership

400 Prince George’s Boulevard

Upper Marlboro, Maryland 20774 

NREL Technical Monitor: Stacey Rothgeb 

Prepared Under Subcontract No. KNDJ-0-40335-00 

September 2012 
iv

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v

Contents

Figures ........................................................................................................................................................ vi

Definitions.................................................................................................................................................. vii

Executive Summary................................................................................................................................. viii

1 Home and Document Inspection in Existing Homes: Whole-House Baseline and Diagnostic 

Inspections............................................................................................................................................ 1

1.1 Home Energy Assessment ...................................................................................................1

1.1.1 Size Things Up.........................................................................................................1

1.1.2 Test In ......................................................................................................................1

1.2 Cost-Benefit Analysis and Estimates...................................................................................5

1.3 Identifying Risks..................................................................................................................7

2 Tradeoffs: Value and Marketing.......................................................................................................... 9

2.1 Measure Selection Criteria, Cost, and Performance ............................................................9

2.2 System Interactions..............................................................................................................9

3 Wall Air Sealing and Insulation Methods in Existing Homes......................................................... 10

3.1 Existing Home Wall Air Sealing Methods ........................................................................10

3.1.1 Materials for Air Sealing .......................................................................................10

3.1.2 Field Inspection......................................................................................................10

3.1.3 Installation Procedure ............................................................................................10

3.1.4 Verification Procedures and Tests.........................................................................11

3.1.5 Benefits..................................................................................................................11

3.1.6 Drawbacks..............................................................................................................11

3.2 Existing Home Wall Insulation Methods...........................................................................11

3.3 Exterior Insulated Sheathing..............................................................................................12

3.3.1 Materials for Insulating..........................................................................................12

3.3.2 Field Inspection......................................................................................................12

3.3.3 Installation Procedure ............................................................................................12

3.3.4 Verification Procedures and Tests.........................................................................13

3.3.5 Benefits..................................................................................................................14

3.3.6 Drawbacks..............................................................................................................14

3.4 Open Framing Cavities – Cavity Insulation (Fiberglass/Cellulose) ..................................14

3.4.1 Materials for Insulating..........................................................................................14

3.4.2 Field Inspection......................................................................................................15

3.4.3 Installation Procedure ............................................................................................15

3.4.4 Verification Procedures and Tests.........................................................................16

3.4.5 Benefits..................................................................................................................16

3.4.6 Drawbacks..............................................................................................................16

3.5 Open Framing Cavities – Spray Foam Insulation (Open/Closed-Cell) .............................16

3.5.1 Materials for Insulating..........................................................................................16

3.5.2 Field Inspection......................................................................................................17

3.5.3 Installation Procedure ............................................................................................17

3.5.4 Verification Procedures and Tests.........................................................................18

3.5.5 Benefits..................................................................................................................18

3.5.6 Drawbacks..............................................................................................................18

3.6 Closed Framing Cavities – Dense-Pack Insulation (Fiberglass/Cellulose) .......................18

3.6.1 Materials for Insulating..........................................................................................18

3.6.2 Field Inspection......................................................................................................18
vi

3.6.3 Installation Procedure ............................................................................................19

3.6.4 Verification Procedures and Tests.........................................................................20

3.6.5 Benefits..................................................................................................................21

3.6.6 Drawbacks..............................................................................................................21

3.7 Interior Insulation on Exterior Mass Walls........................................................................21

3.7.1 Materials for Insulating..........................................................................................21

3.7.2 Field Inspection......................................................................................................22

3.7.3 Installation Procedure ............................................................................................22

3.7.4 Verification Procedures and Tests.........................................................................23

3.7.5 Benefits..................................................................................................................23

3.7.6 Drawbacks..............................................................................................................23

4 Summary and Next Steps .................................................................................................................. 24

References................................................................................................................................................. 25

Appendix A. Air Barrier and Insulation Inspection................................................................................ 27

Appendix B. Air Sealing Key Points(Georgia DCA 2012)...................................................................... 28

Figures

Figure 1. Blower door................................................................................................................................. 2

Figure 2. Duct pressurization test............................................................................................................. 3

Figure 3. Infrared image ............................................................................................................................. 3

Figure 4. Draft pressure testing using combustion analyzer................................................................. 4

Figure 5. Air sealing installation steps ................................................................................................... 11

Figure 6. Exterior foam insulation installation steps ............................................................................ 13

Figure 7. Open framing cavities – sprayed cavity insulation installation steps................................. 16

Figure 8. Open framing cavities – spray foam insulation installation steps ...................................... 17

Figure 9. Closed framing cavities – dense-pack insulation installation steps................................... 20

Figure 10. Interior insulation on exterior walls installation steps (NAHB RC 2010) .......................... 22

Unless otherwise noted, all figures were created by the NAHB Research Center and Southface 

Energy Institute.
vii

Definitions

ASHRAE American Society for Heating, Refrigerating and Air-Conditioning 

Engineers

BPI Building Performance Institute

CAZ Combustion appliance zone 

CFM Cubic feet per minute

DOE U.S. Department of Energy

EPA U.S. Environmental Protection Agency

HVAC Heating, ventilation, and air conditioning

IRC International Residential Code

Pa Pascal

RESNET Residential Energy Services Network 

VAT Vinyl asbestos tile 
viii

Executive Summary

Modern high performance homes feature airtight building envelopes with high levels of thermal 

resistance that control the flows of heat, air, and moisture into and out of the home. Homes built 

before current building codes may have high levels of air leakage and inadequate insulation.

Both issues increase heating and cooling losses and demands on heating, ventilation, and airconditioning systems and decrease occupant comfort and indoor air quality. Air leakage can 

account for a high percentage of heating and cooling bills in an especially leaky house, and 

homes built before 1980 often have little or no wall insulation. Given that walls can represent 

most of the building envelope area, ensuring that walls have proper levels of insulation is an 

essential part of any home energy retrofit. Energy retrofit projects should consider and address 

air sealing in walls and wall junctions to semi-conditioned or unconditioned adjacent spaces.

This guideline provides renovators and retrofit contractors an overview of considerations when 

including wall air sealing and insulation in an energy retrofit project. It also outlines project 

risks, various materials for insulating, possible field inspections needed, installation procedures, 

and the benefits and drawbacks. The purpose of this guideline is to provide the outline of the 

overview and process of insulating and air sealing walls so that home retrofit professionals can 

identify approaches to air sealing and insulation measures.

This new measure guideline builds on Building America research and synthesizes information 

from relevant guidelines from the home energy retrofit industry, as well as weatherization 

education documentation and product manufacturers’ literature. It also includes sidebars of 

“Critical Takeaways,” “Important Definitions,” “Contractor/ Homeowner Safety,” and 

“References to Other Guidelines, Codes, and Standards.” 

Home energy retrofit professionals can share this guideline with homeowners to help them 

understand the retrofit methods that can be employed in their home and the benefits of wall air 

sealing and insulation, including lower energy bills, enhanced durability, and increased comfort. 
1

Important Definitions: Qualified 

Residential Energy Professional

A qualified residential energy 

professional has BPI Building 

Analyst or Energy Auditor 

certification (www.bpi.org), or 

RESNET Home Energy Rater 

certification (www.natresnet.org).

BPI and RESNET certified 

auditors may be independent 

consultants or working on-staff for 

a remodeling or HVAC contractor.

Additional qualified auditors 

include representatives from the 

local utility, or representatives from 

a city or state recognized 

weatherization agency.

An independent third-party auditor 

may be required to participate in 

certain programs such as Home 

Performance with ENERGY 

STAR® (www.energystar.gov) 

sponsored by the U.S. Department 

of Energy (DOE) and U.S. 

Environmental Protection Agency 

(EPA), the National Green Building 

Certification (www.nahbgreen.org) 

Green Remodel Path, or 

EarthCraft House.

1 Home and Document Inspection in Existing Homes: 

Whole-House Baseline and Diagnostic Inspections

The first step in planning any home energy retrofit 

project should include an evaluation of the conditions 

in the home by a qualified residential energy 

professional to determine options for energy upgrades 

and identify any installation or performance issues. For 

example, before wall air sealing and insulation retrofits

are performed, the home energy assessment should 

determine the existing wall conditions and insulation 

and whether any major air leakage pathways are 

present (e.g., at foundation and attic junctions or utility 

or heating, ventilation, and air conditioning (HVAC)

penetrations). Some homes have relatively low levels 

of air leakage and sufficient wall insulation; others are

very leaky with no insulation. This assessment may be 

conducted by an independent auditor, a representative 

from a weatherization agency or local utility company, 

or an employee of the contractor that will implement 

any planned energy upgrades. Homeowners should 

look for independent auditors who have Building 

Performance Institute (BPI) or Residential Energy 

Services Network (RESNET) certification. 

1.1 Home Energy Assessment

This section is based exhaustively on PNNL and ORNL 

(2010).

During a comprehensive home energy assessment, the 

auditor will inspect, evaluate, and analyze the home, 

and will query the homeowners about comfort issues 

and current energy bills. An audit should include the 

following steps:

1.1.1 Size Things Up

The auditor should measure the home and calculate square footage, window area, and door area 

and record the condition of insulation, mechanical equipment, and air leaks. 

1.1.2 Test In

The auditor will use diagnostic equipment to measure how the house performs in ways that 

cannot be detected visually. These tests may include whole-house air leakage, duct leakage, 

infrared thermography scans, and combustion equipment safety assessments.

• Whole-house air leakage. A blower door test system uses a calibrated fan to measure air 

infiltration levels for the whole house. The blower door is mounted at an exterior door 
2 

and the fan pulls air out of the house at a specific pressure (see Figure 1). Outside air then 

flows into the house through all unsealed cracks and openings. The calibrated airflow 

through the fan is a measure of the amount of total air leakage from the home. A record 

of this measurement can then be compared with tests following air sealing upgrades. For 

measuring infiltration rates, the home should be depressurized to 50 Pa below the outside 

reference pressure per RESNET Chapter 8, as well as equipment manufacturers’ and 

energy program guidelines (RESNET). 

Figure 1. Blower door

• HVAC duct air leakage. Leaky, uninsulated (or minimally insulated) ducts in attics, 

basements, or crawlspaces can account for significant heating and cooling energy losses. 

Similar to a blower door, a duct pressurization test uses a calibrated fan to test the 

leakage rate in air ducts. To measure leakage rates, ducts are typically pressurized to 25 

Pa above outside reference pressure following equipment manufacturers’ and energy 

program guidelines. Duct leakage can be expressed in multiple ways, including the fan 

flow (CFM) at 25 Pa (CFM25)/ft2 of conditioned area served, CFM25/100 ft2

, and/or 

percent of system design flow. Duct air leakage tests can either be configured to test total 

leakage or leakage outside the building envelope (see Figure 2). 
3

Figure 2. Duct pressurization test

• Infrared thermography scans. Thermography, using an infrared camera, can be used to 

assess framed wall cavities for the presence and completeness of insulation (Figure 3).

An infrared camera can also be used in conjunction with a blower door to locate 

infiltration pathways. This infiltration test should always be conducted after completing 

cavity insulation inspections. The American Society for Non-Destructive Testing’s Level 

I Thermographer designation provides a minimum level of knowledge for conducting 

building inspections.

Figure 3. Infrared image

• Combustion equipment safety assessment. To determine if vented combustion 

appliances can be backdrafted, a combustion appliance zone (CAZ) worst case 

depressurization test should be conducted following BPI standards (Figure 4). The CAZ 

testing indicates whether combustion equipment could leak combustion gases into the 

home. The auditor should also measure the level of carbon monoxide in the undiluted 

combustion gas and compare to acceptable ranges for the appliance.
4

Figure 4. Draft pressure testing using combustion analyzer
5

1.2 Cost-Benefit Analysis and Estimates

The energy assessment may include use of an energy analysis simulation tool such as REM/Rate, 

BEopt, EnergyGauge, or other software packages to estimate the energy savings when

implementing efficiency measures. The estimated savings can then be compared with estimated 

costs for installing the energy efficiency measures. The cost of the measures divided by the 

annual savings will tell you the “simple payback,” or how many years it will take to recover the 

initial outlay, as shown in the following example. Investments in energy efficiency can be 

viewed in a similar way to financial investments—an outlay of cash results in a return on the 

investment. Beyond monetary benefits, comfort often increases and heating and cooling are more 

consistent. 
6 

Critical Takeaways: Air Sealing and Insulation – Breakout Box for Trade Contractors 

and Remodelers

Project: Air Seal and Insulate From the Outside

The Smiths purchased their 1964 split-level home in the suburbs of Washington, D.C. with 

new carpet and newly painted walls. They had budgeted for the cost of replacing the 

aluminum siding in the spring, but after the move-in, realized that the house was drafty and 

expensive to heat and needed more than just curb appeal. Not wanting to disturb the newly

furnished, pristine interior of their home, the Smiths asked the contractors that were bidding on 

their siding job how they could incorporate air sealing and insulation into the siding project and 

at what cost. The winning contractor presented the following solutions:

Scope of Work: Added Project Cost

1. Add 4 in. of loose fill fiberglass insulation to attic (R-26 to R-40).a $ 864

2. Install gasket at attic access panel and insulation above it. 50

3. Remove soffit from cantilevered floors front and rear; install rigid 

foam air barrier as joist blocking at wall plane and install 1 in. of 

spray polyurethane foam at floor deck and blocking perimeter. Fill 

joist cavity with loose fill fiberglass (R-13–R-35). Trim with prefinished material.

1,224

4. Install a taped and sealed weather resistant barrier over the wall 

sheathing and 1 in. of rigid foam, taped. (Add R-5 to walls.)b

2,120

5. Install new vinyl siding and trim.c Included

Total $ 4,258

Estimated Annual Utility Costs: Before After Savings

Heating $ 1,012 $ 721 $ 291

Cooling 313 313

Water Heating 289 289

Lights, Misc. 693 693

Total $ 2,307 $ 2,016 $ 291

Simple Payback in Years: $4,258/$291 = 15 years

The Smiths’ contractor and the siding manufacturer had provided a limited lifetime warranty on 

the siding, which the Smiths expect to last at least 30 years. By their calculations, the utility 

savings in years 15 through 30 would almost pay for the residing.

a The contractor proposed accessing the attic through the gable end wall before the house was resided to keep the 

traffic and hose applicator out of the house. b The sealed and taped weather-resistant barrier was included in the contractor’s scope of work at no additional 

charge to comply with the siding manufacturer’s warranty. The contractor estimated that these air sealing measures 

employed in the residing project would result in a 25% improvement in air infiltration. c The contractor’s estimate was $3.25 /ft2

 for the siding. Gable end walls were finished with the same materials as the 

main house walls. d Because the Smiths had the work performed during 2010 the portion of the cost directly attributed to insulation cost 

was also eligible for a 30% tax credit. Accordingly, their initial cost for the energy efficiency features netted to 

$3,700, and decreased the simple payback to 12 years. e The cost of increasing the efficiency of the home may be eligible for state, federal, or other incentives, which reduce 

the investment cost and the payback period.
7

1.3 Identifying Risks

Although saving energy is a primary goal for significant air sealing and insulating efforts, just as 

important is maintaining a healthy indoor environment. Older homes may have materials, paints, 

and equipment that are no longer used today. As part of a home assessment, these materials and 

systems, along with other risks such as water leaks, should be clearly identified with provisions

to satisfactorily remediate the risks.

For example, any combustion venting problems identified during CAZ testing must be addressed 

before air sealing begins. The energy assessment should also identify any obvious sources of 

excessive moisture that may lead to indoor air quality problems. Obvious damage to building 

components should also be addressed during the planning for the energy upgrades. The upgrades 

included in a home energy retrofit will also reduce air infiltration and heat loss across the 

envelope, reducing natural air exchange and the ability of wall assemblies to dry following bulk

moisture intrusion.

Professional visual inspections and tests can identify safety and operational problems that may 

require attention before any other work on the house proceeds, including (EPA 2010a):

• Combustion safety. Combustion safety inspections should follow BPI standards (BPI 

2005). 

• Ventilation. Based on post-retrofit infiltration levels, additional controlled mechanical 

ventilation may be necessary and should be installed to have the capability of supplying 

outdoor air at levels prescribed by the American Society of Heating, Refrigerating and 

Air-Conditioning Engineers (ASHRAE) Standard 62.2 (ASHRAE 2010).

• Moisture. Evaluate potential sources of moisture such as bathroom ventilation, window 

and door flashing, and vapor barriers, that will need to be addressed during the energy 

upgrades.

• Lead. Assume that lead paint is present when working in any home built before 1978. 

Renovations and retrofit activities should comply with EPA (2010b) if an area greater 

than 6 ft2 of interior or 20 ft2 of exterior painted surfaces will be disturbed. 

• Asbestos. Asbestos can pose a hazard in homes built after 1930 and before the 1970s, 

and it can also be a concern in homes built or renovated prior to the 1990s. If you are 

unsure whether material contains asbestos, contact a qualified asbestos professional to 

assess the material, sample and test as needed.

• Electricity. If a home has live knob and tube wiring, insulation should not be added to 

wall cavities. Consider installing any new insulation over the exterior of sheathing, with 

exterior wall cladding and sidings installed over the new insulation, or insulate the walls 

at a time when the electrical system is being upgraded.

• Radon. The requirements of the local ordinance for radon mitigation should be followed. 

Where local ordinances do not address radon mitigation for existing buildings, the 

protocol for new construction can be followed with regard to establishing radon hazard 

levels and the need for mitigation measures. Use the EPA Map of Radon Zones (EPA

2012c) or conduct radon testing on site to establish the radon hazard level. If radon level 
8

exceeds 4.0 pCi/L, implement mitigation measures in accordance with ASTM E2121 

(ASTM 2009b).

Contractor/Homeowner Safety: Safety Points

Professionals who combine home improvements with energy efficiency features should

physically examine the house before tightening and insulating it. 

1. Professionally test all combustion appliances and remediate as required (BPI or 

RESNET certified inspector). Have professional discuss results and care and 

maintenance with the homeowners. If absent, include carbon monoxide detector(s) in 

the improvement’s scope of work.

2. If the house was built before 1978, test each unique part that will be impacted by the 

upgrade work for lead paint. If results are positive, follow EPA guidelines (EPA 

2012a,b) for lead-safe work practices or for lead remediation.

3. If the house has an in-ground basement, is in a high or moderate radon potential zone

(EPA 2012c), or does not have a radon abatement system installed, it should be 

tested for radon gas. Homeowner(s) can be tasked with ordering, placing, and 

submitting test kits (EPA 2012d).

4. Visually inspect for asbestos (EPA 2012e). Do not break or otherwise disturb 

asbestos products, as the mineral fibers becoming airborne present the material’s 

hazard. Notify homeowner of damaged surfaces and locations that require 

remediation and work with the homeowner to develop a plan to address these during 

the planned improvement. Asbestos can be left in place, encapsulated, or removed 

and specially disposed of. Possible areas include:

a. Vinyl asbestos tiles (VATs) used in basements, laundry rooms, and kitchens.

Many 12- and 9-in.

2 tiles manufactured between 1950 and 1981 fall in the 

VAT category.

b. Some loose fill attic insulation may contain asbestos mined with the 

vermiculite that was used as insulation.

c. Exterior shingle-style siding was made from asbestos in the mid-20th century.

d. Some furnace and other combustion appliances have asbestos batt insulation 

or backer boards. As with the VAT tiles, these would have been manufactured 

before 1981.

5. Inspect electric service for knob and tube wiring (found in pre-1930 houses). The National 

Electrical Code (NEC) limits loose fill insulation in cavities containing the old wiring (K8T).

6. Inspect wet rooms—kitchen, baths, laundry—for excessive moisture and leaks. Include 

caulk, washers, regrouting, as required, in your Scope of Work. Discuss maintenance 

intervals and offer to provide future service.

7. Inspect for exterior water infiltration areas—flashing, siding and trim junctions, etc. —and 

discuss maintenance interval and service schedule.

8. Develop a climate-appropriate strategy for bringing in outdoor air should the upgrade 

warrant it. ASHRAE Standard 62.2 is a controlled ventilation standard for new and 

existing homes. Be familiar with its recommendations and install controlled mechanical 

ventilation if necessary. 
9

2 Tradeoffs: Value and Marketing

2.1 Measure Selection Criteria, Cost, and Performance

In addition to the home energy assessment, a cost-benefit analysis showing the potential savings 

and payback period for various home energy retrofit options can be provided to the homeowner 

to help in the decision process to select the most beneficial and affordable energy upgrades. 

Compared to other more expensive energy retrofits such as HVAC system replacement, air 

sealing and adding or upgrading wall insulation have the potential to increase homeowner 

comfort, reduce energy consumption and utility bills, and provide a relatively short payback 

period; however, these measures should be considered along with other efficiency upgrades. 

Each home has unique characteristics and conditions, so the specific energy efficiency upgrades 

must be tailored to the situation.

2.2 System Interactions

Because a home functions as a system, with no single component performing independently, it is 

important to consider the impacts of home energy retrofits and the effects upgrades will have on 

existing systems or future system selection. Two of the significant system interactions when 

considering wall insulation and air sealing in existing homes are ventilation to provide outdoor

air and the HVAC system loads and sizing.

Air sealing a home may necessitate the installation of mechanical ventilation based on the blower 

door test results to ensure occupant health and indoor air quality. Mechanical ventilation is 

preferable to relying on infiltration to provide fresh air, as the source and pathway of ventilation 

air can be controlled, reducing contamination and the potential for durability problems.

Alternatively, air sealing can improve the function and effectiveness of existing ventilation 

systems, if present.

Adding wall insulation and reducing air infiltration will also reduce loads on HVAC equipment. 

When energy retrofits coincide with addition projects, adding insulation and air sealing upgrades 

that lower heating and cooling loads can allow an existing system to serve the added living area. 

A smaller unit may be used to replace an oversized system, which will lower the net cost.
10

3 Wall Air Sealing and Insulation Methods in Existing Homes 

Wall air sealing and insulation for existing homes should be considered together in an energy 

retrofit. Together they can significantly improve energy performance. This section outlines 

general air sealing provisions followed by specific considerations of upgrading insulation. The 

goal is to provide remodelers and homeowners an overview of considerations for including wall 

air sealing and insulation in an energy retrofit project.

3.1 Existing Home Wall Air Sealing Methods 

Various materials and methods are used to complete an air sealing job, depending on the 

conditions in the home and the size of the air leakage pathway. Air leaks through building walls 

via two primary modes:

• Bypasses, or large holes in the home’s air barrier

• Seams between building materials (DOE 2007).

3.1.1 Materials for Air Sealing

Materials used to seal air leakage sites must be as close to impermeable to air movement as 

possible and must form a continuous, nonporous surface over the opening being sealed

(DOE 2007).

• Use caulk or spray foam sealant to seal cracks or holes smaller than a pencil width in the 

ceiling, floor, or exterior walls. Seal holes on the inside and outside surfaces of walls.

• For larger openings, use spray foam sealant or fill the crack with backing material and 

caulk the surface (fibrous insulation is not an air sealing material).

• Use sheet materials, such as insulation board or plywood, to cover large holes. Seal the 

edges of the sheet materials with caulk or spray foam sealant. Seal openings between the 

attic and house, and between the crawlspace or basement and house.

3.1.2 Field Inspection 

Large air leakage pathways can be identified through visual inspections. Smaller air leakage 

pathways can be located using a blower door in conjunction with other diagnostic tests, such as a 

smoke pencil or infrared thermography. The contribution from small cracks and holes can be 

significant, and the improvements from identifying and fixing these areas should not be 

discounted.

3.1.3 Installation Procedure

See Figure 5 and Appendices A and B for more information.
11

1. Sealing large bypasses in the air barrier may 

require the use of sheet goods, such as plywood 

or extruded foam sheathing. These rigid barriers 

should be attached with mechanical fasteners 

and sealed with caulk or expanding foam.

2. Seams between building materials and small 

holes or cracks can be sealed using expanding 

foam or caulk. Backer rod can be used for seams 

larger than 5/16 in. to support the air sealing 

product.

Figure 5. Air sealing installation steps

3.1.4 Verification Procedures and Tests

Following air sealing and the completion of all other energy retrofit projects, the home should be 

tested again using a blower door to determine the post-retrofit envelope air leakage levels and to 

determine if mechanical ventilation will be warranted.

3.1.5 Benefits

• Reduces heating and cooling costs.

• Reduces air infiltration through potentially contaminated pathways.

• Increases room comfort.

• Helps to control indoor moisture levels.

3.1.6 Drawbacks

• May be difficult to locate and remediate.

• May involve removing insulation and reinstalling.

• May require access to locations used for storage. 

3.2 Existing Home Wall Insulation Methods 

The method and type of insulation selected for a wall retrofit application depend on many 

factors, including the presence or lack of insulation, the type of insulation, access to framing 

cavities, building façade and structure, project budget, and homeowner preferences. Residential 

wall insulation retrofits can thus be broken down into four categories:

• Exterior insulated sheathing. If the homeowner is open to removing and replacing the 

home’s façade, insulation can be added to the exterior. This can be either a rigid foam or 

mineral wool sheet good, which is added in single or multiple layers over the exterior 

sheathing (if present).
12

• Open framing cavities, gut rehab. In an extensive renovation, often referred to as a gut 

rehab, the interior finish materials in the home (or in a room) are removed so the 

renovation contractor has direct access to the framing cavities to install the insulation. In 

this situation, the insulation methods and materials available to the contractor, including 

blown and spray-applied products, are identical to those in new construction. 

• Closed cavities, dense-pack. For homes with insufficient insulation and where energy 

retrofit work needs to be minimally invasive, insulation can be added to the wall cavities 

using the dense-pack method. Small holes are cut into the walls from the exterior or 

interior to allow access to the framing cavities for insulation application.

• Interior insulation application on exterior walls. For uninsulated exterior mass walls—

block, brick or concrete—insulation can be added to the interior side of the wall. 

Installing foam sheathing directly to the wall and then installing a layer of wall board is 

an effective method for doing this. If the wall is built out, insulation options will be 

identical to those suggested for open cavities (DOE n.d.).

3.3 Exterior Insulated Sheathing

3.3.1 Materials for Insulating

Selection of insulated sheathing will depend on desired performance and project budget. The 

thickness of the sheathing should also be considered, as it will affect the finish details required to 

install new siding and the integration of the new façade with the home’s trim and flashing 

details. 

• Polyisocyanurate provides the highest insulation value; however, it is the most expensive 

and can absorb water, making it unsuitable for below-grade applications. It has an Rvalue of R-5.6–R-8/in.

• Extruded polystyrene has a slightly lower insulation value but it is more impact-resistant 

and does not absorb water. It has an R-value of R-3.8–R-5.0/in.

• Rigid mineral wool panels are vapor permeable, unlike rigid foam sheathing. Mineral 

wool has an R-value of approximately R-3.7/in.

3.3.2 Field Inspection

Before applying new exterior insulation on existing walls, examine the walls for signs of obvious 

moisture problems that should be repaired before, or along with, the energy upgrades.

3.3.3 Installation Procedure

Before proceeding with installation, complete all air sealing details as previously discussed, and 

address and repair any moisture problems. To address air sealing, caulk or foam at penetrations, 

around windows and doors, and at the top and bottom plates of the wall, if accessible. If the foam

will be used as a weather-resistive barrier, tape the seams using manufacturer-recommended 

tape. If not, install house wrap or other weather-resistive barrier directly over the rigid foam. As 

a matter of good practice, repair any damage uncovered during the retrofit process.

When retrofitting rigid foam insulation over the exterior of an existing home, you can install 

insulation directly over the siding if it is flat enough, or apply it directly to the underlying 

oriented strand board, plywood, or dimensional lumber sheathing. Install rigid foam sheathing 
13

according to the manufacturer’s instructions for nail type and nailing pattern. To determine the 

thickness of door and window jamb extensions, measure the combined thickness of the new 

insulation, siding, and any desired air space between the siding and underlying insulated 

sheathing. Also be sure to extend flashings and sills, if necessary (see Figure 6). 

1. Extend door and window 

jambs as necessary.

2. Secure insulation using 

plastic cap nails.

3. Caulk and seal at 

penetrations, and at window 

and door jambs.

4. If foam sheathing will 

function as WRB, tape seams 

according to manufacturer’s 

instructions.

5. If siding is installed in a rain 

screen configuration install 

furring strips attached directly 

to the underlying framing.

6. Install siding according to 

manufacturer’s instructions.

Figure 6. Exterior foam insulation installation steps

3.3.4 Verification Procedures and Tests

Before you install siding, visually inspect the insulated sheathing to ensure all flashing and air 

sealing work has been completed and, if the foam will serve as a weather-resistant barrier, that 

joints have been taped properly. After construction is complete, you should test the home using a 

blower door to determine the post-retrofit leakage levels and if a mechanical ventilation system 

will be warranted.
14

3.3.5 Benefits

The main advantage of applying rigid foam sheathing over the exterior of an existing home is 

that the insulation is continuous, reducing heat loss through uninsulated framing components of 

the home while increasing the insulation at the cavity areas. A layer of exterior insulation in 

addition to cavity insulation can be one of the more efficient wall systems available.

3.3.6 Drawbacks

No matter the type of foam insulation selected for exterior sheathing, installers should recognize 

that adding foam insulation to the exterior of a home reduces the ability of walls to dry to the 

outside, meaning that any wall with exterior foam sheathing should have the ability to dry to the 

home’s interior.

3.4 Open Framing Cavities – Cavity Insulation (Fiberglass/Cellulose)

3.4.1 Materials for Insulating

The selection of cavity insulation for installation from the interior depends on desired 

performance and project budget. Fiberglass batts with air sealing considerations are one option.

In addition, cellulose and fiberglass fibers can be installed into open wall cavities to provide fullfill insulation with increased air sealing properties. 

• Fiberglass batts are frequently installed as cavity insulation.

• Cellulose, an insulation product manufactured from recycled wood fiber, and loose 

fiberglass fibers can be applied in open framing cavities using two approaches:

o The damp-spray approach. The fibers are combined with a wet adhesive and 

sprayed into each individual wall cavity. The additive adheres the material to the 

wall cavity and keeps it stable until the finished material is installed. Following 

installation, excess insulation is trimmed to be even with the interior edge of the 

wall studs. Walls should be allowed to dry out adequately, given the added 

moisture in the adhesive additive.

o The netted approach. This approach employs a mesh net or other similar blanket 

material to hold the insulation in place. It avoids the added moisture of the dampspray approach, and finish materials can be installed immediately following 

insulation.

Fiberglass batts can provide insulation values of R-13–R-15 in a 2 × 4 wall cavity and R-19–

R-21 in a 2 × 6 wall cavity. Depending on installation density, loose fill cellulose and fiberglass 

can provide insulation values of R-3.6–R-3.8/in.
15

3.4.2 Field Inspection

Before installing new insulation, inspect the walls for evidence of obvious moisture or other 

damage that should be repaired before, or along with the energy upgrades. If the condition of the 

façade, sheathing, door and window framing, or interior wall finish indicates moisture problems, 

do not proceed with insulation retrofit until the moisture issue has been identified and repaired. 

3.4.3 Installation Procedure

Before insulation is installed, all air sealing details should be completed and any moisture 

problems addressed and repaired. To address air sealing issues, caulk or foam at penetrations, 

around windows and doors, and at the top and bottom plates of the wall, if accessible. As a 

matter of good practice, repair any damage to the building uncovered during the retrofit process.

All rough-in work in exterior walls should be completed before insulation is installed, and 

junction boxes and other open items should be masked. Insulation should be installed by 

qualified personnel, following the manufacturer’s instructions, but as a rule insulation should fill 

each cavity, completely fitting around electrical wiring, plumbing and other utilities. The use of 

interior vapor barriers should be carefully considered with respect to the IRC (ICC 2012) and 

local requirements (see Figure 7).

References to Other Guidelines, Codes, and Standards: Vapor Barrier

The current edition of the International Residential Code (IRC) (ICC 2012) includes details 

on the use of vapor barriers and is a good resource to determine when the use of interior 

vapor barriers is appropriate. Air sealing the wall and ensuring that there are no exterior 

water leaks provides the most benefit in ensuring good moisture performance in the walls.

The application of interior vapor barrier depends on climate. Three steps to successful water 

management are:

1. Make sure there is no bulk water leakage from the exterior.

2. Minimize air leakage into wall by sealing all penetrations.

3. Use the IRC to determine if the application of an interior vapor barrier is appropriate 

for the climate.
16

1. Complete all air sealing and 

rough-in work before

insulation is installed. Mask 

junction boxes.

2. Apply insulation to fill entire 

cavity, according to 

manufacturer’s instructions.

3. Remove excess insulation if 

necessary.

Figure 7. Open framing cavities – sprayed cavity insulation installation steps

3.4.4 Verification Procedures and Tests

Before drywall is installed, the insulation should be visually inspected and graded per RESNET 

protocols. Grade I insulation should be achieved. After construction is complete, the home 

should be tested with a blower door to determine the post-retrofit leakage levels and if dedicated 

mechanical ventilation will be warranted.

3.4.5 Benefits

• Fiberglass batts are installed by most insulation contractors. They are often a low-cost 

solution for cavity insulation.

• Spray-applied cellulose and fiberglass provide full fill of wall cavities, fitting around 

utility runs and other obstructions. 

• Although they are not a substitute for other air sealing measures, blown cellulose and 

fiberglass provide some additional air sealing benefit.

3.4.6 Drawbacks

• If not installed to achieve Grade I of RESNET protocols, fiberglass batts may be 

compressed, lowering the effectiveness of the insulation.

• If not installed at the prescribed densities, blown fiberglass or cellulose can settle, 

lowering the effectiveness of the insulation by causing open areas at the top of building 

cavities.

3.5 Open Framing Cavities – Spray Foam Insulation (Open/Closed-Cell)

3.5.1 Materials for Insulating

Spray foam insulation has many advantages over other types of insulation because it can

completely fill cavities and provides air sealing benefits. It comes in two varieties, which provide 

different insulation values and moisture permeability characteristics: 
17

• Open-cell foam has insulation values of approximately R-3.6/in. and is permeable to 

moisture. 

• Closed-cell foam has insulation values of up to R-6.5/in. and is not moisture permeable. 

It can also provide additional structural integrity to wall assemblies due to its strength.

3.5.2 Field Inspection

Inspect walls for evidence of moisture or other damage. If the condition of the façade, sheathing, 

door and window framing, or interior wall finish indicates moisture problems, do not proceed 

with insulation retrofit until the issues have been identified and repaired. 

3.5.3 Installation Procedure

Any additional air sealing details that the spray foam will not address (e.g., around windows and 

doors as well as top and bottom plates, if accessible) should be completed and any moisture 

problems addressed and repaired. As a matter of good practice, any damage to the building 

uncovered during the retrofit process should be repaired.

All rough-in work in exterior walls should be completed before insulation is installed. Junction 

boxes and other open items should be masked. Similar to spray cellulose or fiberglass, insulation

should be installed by qualified personnel, following the manufacturer’s instructions. Insulation 

should fill each cavity, completely fitting around electrical wiring, plumbing, and other utilities. 

Wall cavities are not always completely filled, especially when using closed-cell foam, given its 

high cost and insulation value, but in a full fill application a “stud scrubber” is used to remove 

excess insulation material, leaving insulation flush with the face of each cavity. The use of 

interior vapor barriers should be carefully considered with respect to IRC (ICC 2012) and local 

requirements (see Figure 8). Vapor barriers are generally not recommended in walls with spray 

foam insulation.

1. Complete all air sealing 

and rough-in work before

installing insulation. Mask 

junction boxes.

2. Apply foam to desired 

thickness following 

manufacturer’s instructions

3. Remove excess foam if 

necessary

Figure 8. Open framing cavities – spray foam insulation installation steps
18

3.5.4 Verification Procedures and Tests

Before drywall is installed, the insulation should be visually inspected and graded per RESNET 

protocols. Grade I insulation should be easily achieved for spray applied products. After

construction is complete, the home should be tested with a blower door to determine the postretrofit leakage levels and if mechanical ventilation will be warranted.

3.5.5 Benefits

• Blown open- and closed-cell spray foam can provide full fill of wall cavities, fitting 

around utility runs and other obstructions.

• Although they are not a substitute for all air sealing measures (e.g. around windows and 

doors), open- and closed-cell spray foam provide air sealing for the surfaces where they 

are installed.

• Open-cell foam provides air sealing in addition to insulation levels similar to fiberglass 

batts.

• Closed-cell foam has a higher R-value for a given thickness than open cell foam.

3.5.6 Drawbacks

• Spray foam insulation is typically the most expensive option for adding insulation to an 

existing wall.

• Special precautions are necessary when installing large areas of spray foam insulation.

3.6 Closed Framing Cavities – Dense-Pack Insulation (Fiberglass/Cellulose)

3.6.1 Materials for Insulating

• Cellulose and fiberglass fibers can be dense-packed into closed wall cavities to provide 

full fill insulation with additional air sealing properties. 

• Cellulose should be installed at the recommended density of 3.25-4.0 lb/ft3

. 

• Fiberglass fibers should be installed at the recommended density of 1.6 lb/ft3. 

3.6.2 Field Inspection

Inspect walls for evidence of moisture or other damage. If the condition of the building façade, 

sheathing, door and window framing, or interior wall finish indicates moisture problems, do not 

proceed with insulation retrofit until the issues have been identified and repaired. Cracks and 

other evidence of weakness in wall finish materials should also be addressed, as dense-packing 

insulation compresses the insulation in a confined space and further damage can occur at these 

weak points. Repair areas that might be compromised during installation.

Pathways where insulation can escape from wall cavities should also be identified and addressed 

using the air sealing methods discussed previously. These pathways may include electrical 

outlets and switches on exterior walls, utility chases and penetrations, junctions to adjacent 

spaces such as attics and foundations, and open floor cavities. Wall cavities may also be open to 

return air ducts or plenums. Inspect the HVAC system to determine if this is the case, and seal 

and separate wall cavities from ducts and plenums if necessary. Blocking in each wall cavity 

should be located and if found necessitate multiple fill locations in the cavity.
19

3.6.3 Installation Procedure

Before installation is installed, all air sealing details should be completed, and any existing 

problems addressed and repaired. To address air sealing issues, caulk or foam at penetrations, 

around windows and doors, and at the top and bottom plates of the wall, if accessible. As a 

matter of good practice, any damage to the building uncovered during the retrofit process should 

be repaired.

The dense-pack method for retrofitting both fiberglass and cellulose insulation in the closed wall 

cavities of an existing home is quite similar. Whatever the insulation material, it must be 

installed to the required density throughout the entire cavity to reduce the risks of convective 

looping, settling and air leakage. The steps below outline the one-hole dense-packing method, 

the best practice for closed-cavity insulation retrofit (see Figure 9). 

1. Determine whether insulation will be installed from the exterior or interior of the home. 

2. Exterior installation is preferred for occupied homes as it does not disrupt the residents.

3. Exterior installation is preferred for homes with wood, fiber cement, or vinyl siding, and 

asbestos shingles that are not blind nailed.

4. Interior installation is preferred for brick, stucco, or stone façades, and will be easier and 

more cost effective.

5. Cellulose calls for a density of 31⁄4–4 lb/ft3

.

6. Blown fiberglass calls for a density of 1.6 lb/ft3

. 
20

1. Access holes are drilled for 

each cavity, in this case 

through the siding and 

exterior sheathing 

2. Interior installation is 

identical to that of an exterior 

application, but holes are 

drilled directly through interior 

finish material

3. Hole locations are chosen 

based on ease of access to 

minimize the number of 

access holes necessary. 

Additional holes may be 

needed for framing cavity 

areas blocked by obstructions. 

4. Insulation installation 

should begin with full-height 

walls without obstructions to

accurately gauge insulation 

density. Best practice is to fill 

the top of the cavity 

completely and then to 

reinsert the tube to fill the 

bottom of the cavity. The fill 

tube is slowly removed as the 

cavity fills. 

5. After the insulation is 

installed, retrofit access holes 

are sealed using tapered 

wooden plugs. For exterior 

applications siding is 

reinstalled. Interior plugs 

should be spackled and 

prepped for paint finish.

Figure 9. Closed framing cavities – dense-pack insulation installation steps

3.6.4 Verification Procedures and Tests

Given adequate temperature difference across the wall assembly, thermographic scans can be 

used to confirm that insulation has been installed into the entire wall assembly. After

construction is complete, the home should be tested with a blower door to determine the postretrofit leakage levels and if mechanical ventilation will be warranted.
21

3.6.5 Benefits

• Except in the case of very large obstructions, blown cellulose and fiberglass provide full 

fill of wall cavities, fitting around utility runs and other obstructions. 

• Although they are not a substitute for other air sealing measures, blown cellulose and 

fiberglass provide some additional air sealing benefit.

• When installed at higher densities of 1.8 lb/ft3 spray fiberglass can achieve an R-value of 

R-15 in a 2 × 4 cavity and R-21 in a 2 × 6 wall cavity. 

3.6.6 Drawbacks

• Significant wall repair is necessary after the installation.

• Each cavity must be evaluated for the location of blocking.

• Open areas of framing, for example at the location of a tub on an exterior wall, may not 

have any covering to stop the flow of the blown insulation onto the ceiling below.

• Some frame cavities are open to the basement and must be blocked before installing 

insulation.

3.7 Interior Insulation on Exterior Mass Walls

Homes built with mass walls—made of concrete, brick, or block—often have no insulation. In 

this case, a worthwhile insulation retrofit would include adding insulation to the interior side of 

the exterior walls. 

3.7.1 Materials for Insulating

• Insulation on the interior of the exterior concrete or brick walls can be retrofitted using 

various methods, or a combination of methods. Foam sheathing can be applied to the 

block directly or with furring strips. Alternatively, a frame wall may be constructed in 

front of the block or brick wall. Still a third option (see Figure 10), a combination of 

foam sheathing and framing may be used.

• Foam insulation may be either polyisocyanurate (approximate R 6.5/in.) or extruded 

polystyrene (approximate R-5.0/in.). Both can be applied using compatible adhesives or 

special fasteners. Caulks and/or spray foam can be used to seal wall-floor and wallceiling joints.

• Wood framing can be installed in any configuration as it will not serve as the structural 

support when used for building out the wall in front of the main structural wall.

• If framing is used, fiberglass batts or blown insulation may be used to fill the cavities.
22

1. Remove drywall. 2. Install rigid foam and air 

seal.

3. Construct 2 × 4 wall.

4. Insulate 2 × 4 wall. 5. Finish interior walls.

Figure 10. Interior insulation on exterior walls installation steps (NAHB RC 2010)

3.7.2 Field Inspection

Inspect walls for evidence of moisture or other damage. If the condition of the façade, sheathing, 

door and window framing, or interior wall finish indicates moisture problems, do not proceed 

with insulation retrofit until the issues have been identified and repaired. 

Adding insulation to a mass wall will reduce heat transfer across that wall and correspondingly 

reduce drying potential, resulting in more moisture retention in the masonry wall structure. 

Especially in colder climates, this will increase the risk of freeze-thaw damage. Wood beams 

may also be exposed to increased moisture and begin to rot. These risks should be fully 

understood and investigated before interior insulation is installed on mass walls.

3.7.3 Installation Procedure

Before insulation is installed, all air sealing details should be completed, and any moisture 

problems addressed and repaired. To address air sealing issues, caulk or foam at penetrations, 

around windows and doors, and at the top and bottom plates of the wall, if accessible. As a 

matter of good practice, any damage to the building uncovered during the retrofit process should 

be repaired.
23

Rigid foam insulation should be retrofitted directly over the interior of a mass wall with

mechanical fasteners according to the manufacturer’s instructions. Once foam is in place, furring 

strips should be installed to allow for drywall installation. Alternatively, interior walls could be 

built out allowing for the installation of additional cavity insulation. Window and door openings 

must be framed to accommodate the new interior insulation and/or framing. Careful air sealing 

and window flashing detail are needed to avoid future moisture problems.

3.7.4 Verification Procedures and Tests

When construction is complete, the home should be tested with a blower door to determine the 

post-retrofit leakage levels and if mechanical ventilation will be warranted.

3.7.5 Benefits

• Rigid foam sheathing installed over the interior of a mass wall significantly increases the 

wall thermal performance and provides an opportunity for air sealing and moisture 

protection.

• Interior insulation installed using framing members can provide an opportunity to 

upgrade and locate electrical and duct systems out of the mass wall and insulated behind 

these systems.

3.7.6 Drawbacks

• Installing insulation over existing interior finish surfaces may necessitate the relocation 

of utilities, junction boxes, and other items not needing upgrades.

• Window and door openings will require new jamb extensions and new framed openings.

• Reduced drying potential from added insulation may lead to freeze-thaw damage, rot of 

embedded wood beams, and other durability issues.

Critical Takeaways: Insulation and Air Sealing Overview

This guide provides renovators and retrofit contractors an overview of 

considerations when including wall air sealing and insulation in an energy retrofit 

project. 

Before proceeding with any insulation installation, all air sealing details should be 

completed. Then, based on costs and energy performance the goal is to select the 

wall insulation method and material for the retrofit.

The benefits, drawbacks, field inspection, installation procedure, and verification 

procedures and tests for various materials are detailed, including:

• Exterior foam 

• Open framing cavity fiberglass and cellulose insulation

• Closed cavity dense pack fiberglass and cellulose 

• Interior insulation application on mass exterior walls. 
24

4 Summary and Next Steps

This guideline provides renovators and retrofit contractors an overview of considerations when 

including wall air sealing and insulation in an energy retrofit project. The purpose is to provide 

the necessary information and guidance to home retrofit professionals to assess energy upgrade

opportunities in the walls of an existing home and identify approaches to air sealing and 

insulation measures. All air sealing details should be completed before any insulation is installed.

Then, based on costs and energy performance the goal is to select the wall insulation method and 

material for the retrofit. The overview outlines the benefits, drawbacks, field inspection, 

installation procedure, and verification procedures and tests of exterior foam, open framing 

cavity fiberglass and cellulose insulation, closed cavity dense pack fiberglass and cellulose, and 

interior insulation application on mass exterior walls. The next step is to produce detailed 

installation guides for each type of insulation in the overview and the specific air sealing 

considerations for each.
25

References

ASHRAE. (2010). ASHRAE Standard 62.2-2010 Ventilation and Acceptable Indoor Air Quality 

in Low-Rise Residential Buildigns. Atlanta, GA: American Society of Heating, Refrigerating and 

Air-Conditioning Engineers, Inc.

ASTM. (2003). ASTM C1060 - 90(2003) Standard Practice for Thermographic Inspection of 

Insulation Installations in Envelope Cavities of Frame Buildings. West Conshohocken, PA: 

American Society for Testing and Materials.

ASTM. (2009a). ASTM E1186 -03(2009) Standard Practices for Air Leakage Site Detection in 

Building Envelopes and Air Barrier Systems. West Conshohocken, PA: American Society for 

Testing and Materials.

ASTM. (2009b). ASTM E2121 - 09 Standard Practice for Installing Radon Mitigation Systems in 

Existing Low-Rise Residential Buildings. West Conshohocken, PA: American Society for 

Testing and Materials.

BPI. (2005). Building Performance Insitute Technical Standards for the Building Analyst 

Professional. Malta, NY: Building Performance Institute.

DOE. (2007). Midwest Weatherization Best Practices Field Guide. Chicago, IL: U.S. 

Department of Energy Midwest Regional Office.

DOE. (n.d.) Insulation and Air Sealing. 

www.energysavers.gov/your_home/insulation_airsealing/index.cfm/mytopic=11220

EPA. (2010a). Healthy Indoor Environment Protocols for Home Energy Upgrades. Washington,

D.C.: U.S. Environmental Protection Agency.

EPA. (2010). The Lead-Safe CerTified Guide To Renovate Right. Washington, D.C.: U.S. 

Environmental Protection Agency.

EPA. (2012a). Testing Your Home for Lead in Paint, Dust, and Soil. Washington, D.C.: U.S. 

Environmental Protection Agency. www.epa.gov/lead/pubs/leadtest.pdf.

EPA. (2012b). Lead Abatement Professionals. Washington, D.C.: U.S. Environmental Protection 

Agency. www.epa.gov/lead/pubs/traincert.htm.

EPA. (2012c). Map of Radon Zones. Washington, D.C.: U.S. Environmental Protection Agency. 

www.epa.gov/radon/zonemap.htm.

EPA. (2012d). Home Buyer’s and Seller’s Guide to Radon. Washington, D.C.: U.S. 

Environmental Protection Agency. www.epa.gov/radon/pubs/hmbyguid.html.

EPA. (2012e). Asbestos in Your Home. Washington, D.C.: U.S. Environmental Protection 

Agency. www.epa.gov/asbestos/pubs/ashome.html.
26

Georgia DCA. (2011). Georgia State Supplements and Amendments to the International Energy 

Conservation Code (2009 Edition). Atlanta, GA: U.S. Georgia Department of Community 

Affairs.

ICC. (2012). International Residential Code. Washington, D.C.: International Code Council. 

www.iccsafe.org.

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

Council. www.iccsafe.org.

Krigger, J., & Dorsi, C. (2004). Residential Energy Cost Savings and Comfort for Existing 

Buildings. Helena, MT: Saturn Resource Management, Inc.

NAHB Research Center. (2010). ENERGY PERFORMANCE REMODELING Case Study: 

Habitat for Humanity Montgomery County (HFH-MC) Montgomery County, MD. Upper 

Marlboro, MD: NAHB Research Center.

PNNL and ORNL. (2010). Retrofit Techniques & Technologies: Air Sealing A Guide for 

Contractors to Share with Homeowners. Richland, WA: Pacific Northwest National Laboratory

and Oak Ridge, TN: Oak Ridge National Laboratory.

RESNET. (2006). Mortgage Industry National Home Energy Rating Systems Standards.

Oceanside, CA: Residential Energy Services Network.
27

Appendix A. Air Barrier and Insulation Inspection

2009 International Energy Conservation Code, Table 402.4.2 (ICC 2009)

Number Component Criteria

1 Air Barrier and Thermal Barrier

Exterior thermal envelope insulation for framed walls is 

installed in substantial contact and continuous with 

building envelope air barrier.

Breaks or joints in the air barrier are filled or repaired.

Air-permeable insulation is not used as a sealing material.

2 Ceiling/attic Air barrier in any dropped ceiling/soffit is substantially 

aligned with insulation and any gaps are sealed

Attic access (except unvented attic), knee wall door, or 

drop down stair is sealed.

3 Walls Corners and headers are insulated.

Junction of foundation and sill plate is sealed.

4 Windows and doors Space between window/door jambs and framing is sealed.

5 Rim joists Rim joists are insulated and include an air barrier.

6

Floors

(including above garage and 

cantilevered floors)

Insulation is installed to maintain permanent contact with 

underside of subfloor decking.

Air barrier is installed at any exposed edge of floor.

7 Crawlspace walls

Insulation is permanently attached to walls.

Exposed earth in unvented crawlspaces is covered with 

Class I vapor retarder with overlapping joints taped.

8 Shafts, penetrations Duct shafts, utility penetrations, knee walls and flue shafts 

opening to exterior or unconditioned space are sealed.

9 Narrow cavities Batts in narrow cavities are cut to fit, or narrow cavities are 

filled by sprayed/blown insulation.

10 Garage separation Air sealing is provided between the garage and conditioned 

spaces.

11 Recessed lighting Recessed light fixtures are airtight, IC rated and sealed to 

drywall.

Exception—fixtures in conditioned space.

12 Plumbing and wiring

Insulation is placed between pipes and exterior. Batt 

insulation is cut to fit around wiring and plumbing, or 

sprayed/blown insulation extends behind piping and wiring.

13 Shower/tub on exterior wall Showers and tubs on exterior walls have insulation and an 

air barrier separating them from the exterior wall.

14

Electrical/phone box on exterior 

wall Air barrier extends behind boxes or air sealed type boxes 

are installed.

15 Common wall Air barrier is installed in common wall between dwelling 

units.

16 HVAC register boots HVAC register boots that penetrate building envelope are 

sealed to subfloor or drywall.

17 Fireplace Fireplace walls include an air barrier.
28

Appendix B. Air Sealing Key Points(Georgia DCA 2012)
29
30
31
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DOE/GO-102012-3682 ▪ September 2012

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