Blown Insulation for Existing Vented Attic

Scope

Insulate a vented attic in an existing home by installing blown insulation on the ceiling deck of the attic, as follows:

  • Before any retrofit work is done, inspect the roof and attic; repair any leaks, remove active knob and tube wiring, and remediate any hazardous materials.
  • If existing bath fans vent into the attic, they must be vented to the outside.
  • Remove any existing insulation, debris and dust, and prepare the attic floor for air sealing and loose-fill fibrous insulation.
  • Seal all attic floor penetrations with sealant, one-part spray foam, or rigid blocking material as needed.
  • Verify that proper ventilation of the attic is provided with soffit vents (preferred) or gable and ridge vents. Verify that there is a baffle at each soffit vent extending from the top plate to above the height of the insulation to provide a pathway for ventilation air while keeping insulation out of the soffit vents.
  • Install blown loose-fill insulation over the attic floor to levels that meet or exceed the current adopted building and energy codes.

This approach is suitable for projects with a vented attic where the thermal boundary is established at the attic floor/ceiling plane. This approach requires that there be sufficient height between the underside of the roof deck and the top plate at the eave to install the full code-required amount of insulation while maintaining an air gap for ventilation above the insulation. Installing HVAC ducts and air handlers in vented attics is not recommended.

Description

Many older homes have little or no attic insulation. Loose-fill insulation such as blown cellulose or blown fiberglass can be installed at the ceiling plane/attic floor to improve thermal performance in a vented attic.

Care should be taken when installing blown insulation to ensure that it fills all ceiling joist bays with no gaps or voids around wiring or piping and that it covers the tops of the joists to stop thermal bridging. The depth of coverage should be even across the field of the attic. The blown insulation should be installed in accordance with RESNET Grade 1 installation criteria.

The ceiling plane or attic floor should be thoroughly air sealed prior to installing insulation. Robust and continuous air control is critical to a high-performance thermal enclosure. The existing insulation must be removed to provide access to the ceiling plane for air sealing. Debris and dust should also be removed so that sealants will have good adhesion. Seal all cracks, seams and holes using caulk or spray foam sealants. Use solid blocking for any larger holes or open soffits. Metal blocking and collars can be constructed around hot flues to keep insulation from touching them. Covers can be purchased or constructed to cover, air seal, and insulate recessed can lights that are not insulated ceiling airtight (ICAT) rated. See Attic Air Sealing Guide and Details.

If existing insulation was removed from the attic floor to perform air sealing, it may be reinstalled if it is in good condition. However, existing attic insulation is often contaminated with construction debris, plaster scraps, animal droppings, etc. Older loose-fill may be vermiculite insulation which can contain asbestos. The safest approach may be to dispose of the old insulation and install only new insulation.

The presence of flooring above the ceiling joists in an attic will make it difficult to air seal at the ceiling plane (attic floor). If the air control is to be established at the ceiling plane, then any attic flooring installed above that must be removed to provide full access to the ceiling surface.  [CAUTION: In some cases, floor sheathing may resist the lateral thrust of roof framing. If floor sheathing is attached to framing that is perpendicular to the slope of the roof (perpendicular to the ridge or eave), do not remove the floor sheathing without first consulting a qualified building professional.] Alternately, it may be possible to transition the air barrier to the top of the existing attic floor. To successfully execute this option, sufficient insulation is required outboard (on top of) the floor to control condensation and a robust air control connection must be made from the top of the exterior walls to the perimeter of the attic flooring. 

In climate zones 6 or higher, a Class I vapor barrier (e.g., polyethylene) or Class II vapor retarder should be installed above the ceiling drywall as required by code. Class I vapor barriers should be avoided in climate zones 5 and below, as condensation can occur on the attic side of the vapor barrier in summer months during air conditioning periods. (See BSD 102 Attic Ventilation.) 

One benefit of a vented (rather than unvented) attic is that interior-sourced moisture will be vented out of the attic space before causing damage to the roof sheathing. Another advantage of vented attics in cold climates is that they help to reduce the chances of ice damming on the roof. Ice dams occur when heat leaks from the conditioned space (through holes in the ceiling plane, insufficient insulation, or heat loss from ductwork) and melts the snow on the roof. This melted snow travels down to the edges of the roof where it refreezes, creating icicles and ice dams. Attic ventilation helps to “flush away” this heat before it can melt the snow. See BSI-046: Dam Ice Dam, and BSD-135: Ice Dams.  

The vented attic approach requires that there be sufficient height at the attic eaves for code-level required amounts of insulation. In mixed- and cold climates (zones 4 and above), inadequate insulation raises risks of wintertime condensation at the top plate due to cold surfaces. If the roof is too low at the eaves to install adequate amounts of blown insulation, then alternative solutions are to fill the space over the top plate to the baffle with closed-cell spray foam or to cover the top plate area with rigid foam board. (Spray foam and rigid foam have higher R-values per inch than blown insulation. Spray foam has the added advantage of air sealing the top plate-to-drywall seams and the baffle-to-top plate seam.) Another option is to convert the attic to a sealed, insulated space by sealing the soffit vents and insulating along the underside of the ceiling deck with closed-cell spray foam or above the roof deck with rigid foam. In new home construction, a common solution to increase the roof height for insulation above the top plate is to use raised heel trusses. Older existing roofs are unlikely to have raised heel trusses and raised heel trusses are not likely to be installed as a retrofit measure unless a complete reconstruction of the roof is required, for example if a second or third story is being added.

The vented attic approach requires that there be sufficient height at the attic eaves to maintain an air gap above the insulation for ventilation air traveling from the soffit vents to the ridge vents. The vent space should be at least 2 inches high and the width of the framing bay at each soffit vent (Lstiburek 2006). Baffles should be installed at each soffit vent to provide this pathway for ventilation air to move up past the insulation along the underside of the roof deck to ridge vents or mushroom cap vents located near the ridge. The lower edge of the baffle can be sealed to the attic floor at the outside edge of the top plate with spray foam, which also air seals the top plate-to-dry wall seams. The baffles also serve to prevent insulation from covering the soffit vents and they can prevent “wind washing,” i.e., when wind blows in the soffit vents and pushes the insulation back from the eaves. 

If the attic does not have soffit vents, attic ventilation can be provided by installing other types of vents such as gable or eyebrow vents down low near the attic floor, along with ridge vents or mushroom cap vents located up near the roof ridge.

Powered attic ventilators (thermostatically controlled fans that exhaust attic air during hot weather) can result in increased infiltration (and associated higher cooling loads).  Studies have shown that powered ventilators have higher electricity consumption than their associated air conditioner savings (FSEC 2005/ Literature Review of the Impact and Need for Attic Ventilation in Florida Homes).

Installing HVAC ducts and air handlers in vented attics is not recommended. Locating ductwork and/or air handling equipment in a vented attic can contribute to energy losses, performance issues, and ice dam formation in snowy climates, especially if the ducts and air handlers are leaky or poorly insulated.  One exception is if the ductwork can be encapsulated in spray foam and buried beneath the attic floor blown insulation. The ducts must be tightly air sealed and covered with a sufficient amount of spray foam insulation to minimize the risk of condensation forming on the outside of the ducts. See Ducts Buried in Attic Insulation.  However, because mechanical equipment such as air handlers cannot be adequately air sealed, locating them in a vented attic is not recommended. If the air handler must be located in the attic then consider converting the attic to a sealed, insulated space.

Vented attic with loose-fill fibrous insulation at attic floor

Figure 1. Vented attic with loose-fill fibrous insulation at attic floor. Reference

How to Insulate Attic Floor with Blown Insulation

1.  Before any retrofit work is done, inspect the work area for active knob and tube wiring, bathroom fans venting into attics, roof leaks, and other hazardous conditions. Repair these conditions prior to adding insulation. Inspect for and remove or remediate hazardous materials like asbestos-containing vermiculite insulation.

2.  Remove any existing insulation, debris and dust, and clean the work area to allow for an adequate adhesion of sealant.

Clean the attic floor of debris prior to installing new attic insulation. Use baffles to provide a path for ventilation air entering attic from soffit vents

Figure 2. Clean the attic floor of debris prior to installing new attic insulation. Use baffles to provide a path for ventilation air entering attic from soffit vents. Reference

3.  Seal all ceiling joints and penetrations with sealant. Seal top plate-to-drywall seams and top plate-to-baffle seams. Provide additional solid blocking for large holes and open soffits, install metal blocking and collars around hot flues, and install covers over non-ICAT-rated recessed can lights. See BSC, 2013. Attic Air Sealing Guide and Details.  Don’t block intentional openings such as combustion air ducts and soffit, ridge, and gable vents.

Seal drywall-to-top plate seams. Seal lower edge of baffle to top plate to prevent incoming air from soffit vents from flowing under baffles into insulation

Figure 3. Seal drywall-to-top plate seams. Seal lower edge of baffle to top plate to prevent incoming air from soffit vents from flowing under baffles into insulation. Reference

Seal all ceiling joists, drywall-to-top plate seams, and penetrations at the attic floor

Figure 4. Seal all ceiling joists, drywall-to-top plate seams, and penetrations at the attic floor. Reference

4.  Verify that proper ventilation of the attic is provided with soffit and ridge vents or eyebrow, gable end, mushroom cap, and/or other vents. (See Figure 5.) If soffit vents exist, inspect existing baffles and install new baffles if needed (see Figure 3).

Four attic venting approaches for vented attics that don’t have soffit vents - vents are installed low for incoming air and high for outgoing air

Figure 5. Four attic venting approaches for vented attics that don’t have soffit vents - vents are installed low for incoming air and high for outgoing air. Reference

5.  Install loose-fill fibrous insulation over the attic floor to levels that meet or exceed the current adopted building and energy codes for thermal performance. Cover the entire ceiling all the way to the top plate to provide adequate thermal resistance. The depth of the fibrous insulation should be as even as possible.

Loose-fill fibrous insulation is installed against the baffle to full code-required insulation height

Figure 6. Loose-fill fibrous insulation is installed against the baffle to full code-required insulation height. Reference

Ensuring Success

Remediate or remove all hazardous conditions and materials prior to beginning any retrofit work. Examples of hazardous materials that may be found in attic/roof assemblies of existing structures include (but are not limited to) lead, asbestos, mold, animal dropping/remains, etc. Follow applicable laws and industry procedures for mitigation of hazardous materials. Engage the services of a qualified professional when needed.

For more information on vermiculite, see the EPA guide: Protect Your Family from Asbestos – Contaminated Vermiculite Insulation.

For guidance on handling knob and tube wiring, see Weatherization Assistance Program guide: Retrofitting Insulation in Cavities with Knob-and-Tube Wiring an Investigation into Codes, Safety, and Current Practices.

Seal all penetrations to provide a continuous air control layer at the attic floor. Visual inspection, infrared thermography, and blower door testing are all tools that can be used to verify air barrier continuity.

Install loose-fill fibrous insulation to provide adequate thermal resistance and to the levels specified in the current adopted building and energy codes.

Electrical junction boxes accessible from the attic will be buried during this insulation retrofit.  The NEC (Article 314.29, 2005 NEC) requires junction boxes to be accessible "without removing any part of the building."  This clause could be interpreted as including or excluding attic insulation.  The ideal approach would elevate the junction box above the insulation level; alternately, a flag marker could be placed to indicate junction box location.  A local code official could provide further guidance.

All roofs must be vented according to the applicable current adopted building code.  If the roof is not vented according to the applicable building code then a qualified contractor in the state should be engaged to install the necessary venting.

Climate

The ceiling/attic floor assembly should be designed for a specific hygrothermal region, rain exposure zone and interior climate.  The climate zones are shown on the map below, which is taken from Figure C301.1 of the 2012 IECC. 

IECC climate zone map

The insulation levels should be based on the minimum requirements for vapor control in the current adopted building code and the minimum requirements for thermal control in the current energy code. The table below provides the minimum thermal resistance (R-value) requirements specified in the 2009 IECC (ICC 2009b) and the 2012 IECC (ICC 2012b) based on climate zone for ceiling/attic floor assemblies.

Table 1. Attic Insulation Requirements per the 2009 and 2012 IECC

Training

Right and Wrong Images

Presentations

None Available

Videos

None Available

CAD Images

None Available

Compliance

The Compliance tab contains both program and code information. Code language is excerpted and summarized below. For exact code language, refer to the applicable code, which may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

ENERGY STAR Certified Homes

[Guidance for Version 3.0, Rev 08 is coming soon.]

ENERGY STAR Certified Homes is a voluntary high-performance home labeling program for new homes operated by the U.S. Department of Energy and the U.S. Environmental Protection Agency. Builders and remodelers who are conducting retrofits are welcome to seek certification for existing homes through this voluntary program.

ENERGY STAR Certified Homes (Ver 3.0, Rev 07) requires that ceiling, wall, floor, and slab insulation levels meet or exceed those specified in the 2009 International Energy Conservation Code (IECC).

See the interactive map of 2009 IECC insulation levels by climate zone.

If the state or local residential building energy code requires higher insulation levels than those specified in the 2009 IECC, you must meet or exceed the locally mandated requirements. Some states have adopted the 2012 IECC. Visit the U.S. DOE Building Energy Codes Program to see what code has been adopted in each state. For states that have adopted the 2012 IECC or an equivalent code, EPA intends to implement the ENERGY STAR Certified Homes Version 3.1 National Program Requirements for homes permitted starting one year after state-level implementation of the 2012 IECC or an equivalent code. However, EPA will make a final determination of the implementation timeline on a state-by-state basis. Some states and regions of the country have ENERGY STAR requirements that differ from the national requirements. Visit ENERGY STAR’s Regional Specifications page for more information on those region-specific requirements.

The ENERGY STAR Thermal Enclosure System Rater Checklist (Ver 3, Rev 07) specifies:

2.1 Ceiling, wall, floor and slab insulation levels shall comply with one of the following options:

2.1.1 Meet or exceed 2009 IECC levels, OR

2.1.2 Achieve <= 133% of the total UA resulting from the U-factors in 2009 IECC Table 402.1.3, excluding fenestration and per guidance in note “d” below, AND home shall achieve <= 50% of the infiltration rate in Exhibit 1 of the National Program Requirements.

(3) Insulation levels in a home shall meet or exceed the component insulation requirements in the 2009 IECC - Table 402.1.1. The following exceptions apply:

      1. Steel-frame ceilings, walls, and floors shall meet the insulation requirements of the 2009 IECC Table 402.2.5. In CZ 1 and 2, the continuous insulation requirements in this table shall be permitted to be reduced to R-3 for steel-frame wall assemblies with studs spaced at 24 inch on center. This exception shall not apply if the alternative calculations in "d" below are used;
      2. For ceilings with attic spaces, R-30 shall satisfy the requirement for R-38 and R-38 shall satisfy the requirement for R-49 wherever the full height of uncompressed insulation at the lower R-value extends over the wall top plate at the eaves. This exemption shall not apply if the alternative calculations in "d" are used;
      3. For ceilings without attic spaces, R-30 shall satisfy the requirement for any required value above R-30 if the design of the roof/ceiling assembly does not provide sufficient space for the required insulation value. This exemption shall be limited to 500 square feet or 20% of the total insulated ceiling area, whichever is less. This exemption shall not apply if the alternative calculations in "d" are used;
      4. An alternative equivalent U-factor or total UA calculation may also be used to demonstrate compliance, as follows: An assembly with a U-factor equal or less than specified in 2009 IECC Table 402.1.3 complies. A total building thermal envelope UA that is less than or equal to the total UA resulting from the U-factors in Table 402.1.3 also complies. The insulation levels of all non-fenestration components (i.e., ceilings, walls, floors, and slabs) can be traded off using the UA approach under both the Prescriptive and the Performance Path. Note that fenestration products (i.e., windows, skylights, doors) shall not be included in this calculation. Also, note that while ceiling and slab insulation can be included in trade-off calculations, the R-value must meet or exceed the minimum values listed in Items 4.1 through 4.3 of the ENERGY STAR Checklist to provide an effective thermal break, regardless of the UA tradeoffs calculated. The UA calculation shall be done using a method consistent with the ASHRAE Handbook of Fundamentals and shall include the thermal bridging effects of framing materials. The calculation for a steel-frame envelope assembly shall use the ASHRAE zone method or a method providing equivalent results, and not a series-parallel path calculation method.

DOE Zero Energy Ready Home

The DOE Zero Energy Ready Home Program is a voluntary high-performance home labeling program for new homes operated by the U.S. Department of Energy. Builders and remodelers who are conducting retrofits are welcome to seek certification for existing homes through this voluntary program.

The U.S. Department of Energy Zero Energy Ready Home National Program Requirements specify as a mandatory requirement (Exhibit 1, #2.2) that, for all labeled homes, whether prescriptive or performance path, ceiling, wall, floor, and slab insulation shall meet or exceed 2012 IECC levels. See the guide 2012 IECC Code Level Insulation – DOE Zero Energy Ready Home Requirements for more details.

2009 IECC

Section 101.4.3 Additions, alterations, renovations or repairs.  Portions of an existing building that are altered in the course of additions, alterations, renovations or repairs must be brought into conformance with the code with the following exceptions applicable to attic/roof retrofit: existing ceiling wall or floor cavities that are exposed provided the cavities exposed are filled with insulation; addition, alteration, renovation or repair projects that do not expose the existing roof, wall or floor cavity; reroofing that does not expose the insulation nor the sheathing.*

Section 101.4.5 Change in space conditioning.  This section states that spaces must be brought into full compliance with the new construction requirements if the addition, alteration, renovation or repair changes that space from unconditioned to conditioned space.*

Section 402 Building Thermal Envelope. Table 402.1.1 indicates the prescriptive requirements for building enclosure components.*

Section 402.2.1 Ceilings with attic spaces. This section indicates that the prescriptive requirement for R-38 ceiling insulations is deemed to be met by R-30 insulation when the R-30 insulation extends over the wall top plate at eaves and when the insulation is at full loft and uncompressed over the wall top plate at eaves.  Similarly, R-38 insulation is recognized to satisfy the requirement for R-49 insulation when R-38 insulation extends over the wall top plate at eaves and when the insulation is at full loft and uncompressed over the wall top plate at eaves.*

Section 402.3. Access hatches and doors. Doors or hatches separating conditioned spaces from unconditioned spaces (such as attics and crawl spaces) must be weather stripped and insulated to a level equivalent to that of surrounding assemblies.  When loose fill insulation is used, insulation dams are required around attic hatches.*

Section 402.4 Air Leakage.  This section indicates that the building thermal envelope (as it is called in the IECC) must be sealed to limit infiltration and that it must be sealed in a manner that is durable allowing for differential expansion and contraction.*

2009 IRC

Appendix J, Section 501.6, Ventilation.  The appendix is not attached to the requirements of the IRC unless it is specifically included by the adopting jurisdiction.  This section of the appendix indicates that any space that is changed to be habitable or occupiable by alteration must be provided with ventilation in accordance with Section R303.*

Section R806.3 Vent and insulation clearance.  A vent space clearance of at least 1” must be maintained at the location of the vent and between insulation and roof sheathing.*
Note that this would not apply where an unvented roof assembly is used as indicated in section R806.4.

Section R807.1 Attic access.  An attic access is required where the ceiling or roof construction is combustible and where the attic area is more than 30 sf and the height between the ceiling framing and roof framing is more than 30”.*  Refer to specific language of this section for required dimensions of the access.

Section N1102.2.1 Ceilings with attic spaces. This section indicates that the prescriptive requirement for R-38 ceiling insulations is deemed to be met by R-30 insulation when the R-30 insulation extends over the wall top plate at the eaves and when the insulation is at full loft and uncompressed over the wall top plate at the eaves.  Similarly, R-38 insulation is recognized to satisfy the requirement for R-49 insulation when R-38 insulation extends over the wall top plate at eaves and when the insulation is at full loft and uncompressed over the wall top plate at eaves.*

Section N1102.2.3 Access hatches and doors. Doors or hatches separating conditioned spaces from unconditioned spaces (such as attics and crawl spaces) must be weather-stripped and insulated to a level equivalent to that of surrounding assemblies.  When loose fill insulation is used, insulation dams are required around attic hatches.*

Section N1102 Building Thermal Envelope. Table N1102.1 indicates the prescriptive requirements for building enclosure components.*

Section N1102.4 Air Leakage.  This section indicates that the building thermal envelope (as it is called in the IRC) must be sealed to limit infiltration and that it must be sealed in a manner that is durable allowing for differential expansion and contraction.*

2012 IECC

Section R101.4.3 Additions, alterations, renovations or repairs.  Portions of an existing building that are altered in the course of additions, alterations, renovations or repairs must be brought into conformance with the code with the following exceptions applicable to attic/roof retrofit: existing ceiling wall or floor cavities that are exposed provided the cavities exposed are filled with insulation; addition, alteration, renovation or repair projects that do not expose the existing roof, wall or floor cavity; reroofing that does not expose the insulation nor the sheathing.*

Section R101.4.5 Change in space conditioning.  This section states that spaces must be brought into full compliance with the new construction requirements if the addition, alteration, renovation or repair changes that space from unconditioned to conditioned space.*

Section R402 Building Thermal Envelope. Table R402.1.1 indicates the prescriptive requirements for building enclosure components.*

Section R402.2.1 Ceilings with attic spaces. This section indicates that the prescriptive requirement for R-38 ceiling insulations is deemed to be met by R-30 insulation when the R-30 insulation extends over the wall top plate at eaves and when the insulation is at full loft and uncompressed over the wall top plate at eaves.  Similarly, R-38 insulation is recognized to satisfy the requirement for R-49 insulation when R-38 insulation extends over the wall top plate at eaves and when the insulation is at full loft and uncompressed over the wall top plate at eaves.*

Section R402.2.3 Eave baffle.  This section indicates the requirement for baffles to be installed next to eave and soffit vents for vented attics using air permeable insulations.  The baffle can be any solid material, must extend to the top of the attic insulation, and must maintain an opening that is at least as large as the vent.*
Note that baffles should also be used with vented cathedral assemblies.

Section R402.2.4 Access hatches and doors. Doors or hatches separating conditioned spaces from unconditioned spaces (such as attics and crawl spaces) must be weather-stripped and insulated to a level equivalent to that of surrounding assemblies.  When loose fill insulation is used, insulation dams are required around attic hatches.*

Section R402.4 Air Leakage.  This section indicates that the building thermal envelope (as it is called in the IECC) must be sealed to limit infiltration and that it must be sealed in a manner that is durable allowing for differential expansion and contraction.*

2012 IRC

Appendix J, Section 501.6, Ventilation.  The appendix is not attached to the requirements of the IRC unless it is specifically included by the adopting jurisdiction.  This section of the appendix indicates that any space that is changed to be habitable or occupiable by alteration must be provided with ventilation in accordance with Section R303.*

Section R806.3 Vent and insulation clearance.  A vent space clearance of at least 1” must be maintained at the location of the vent and between insulation and roof sheathing.*

Section R806.4 Installation and weather protection.  This section indicates that ventilators for roofs are to be installed in accordance with manufacturer’s installation instructions and the requirements of Section R903.

Section R807.1 Attic access.  An attic access is required where the ceiling or roof construction is combustible and where the attic area is more than 30 sf and the height between the ceiling framing and roof framing is more than 30”.*  Refer to specific language of this section for required dimensions of the access.

Section R901 Roof Assemblies.  This section outlines the design, materials, construction and quality of roof assemblies.

Section N1102 Building Thermal Envelope. Table N1102.1.1 indicates the prescriptive requirements for building enclosure components.*

Section N1102.2.1 Ceilings with attic spaces. This section indicates that the prescriptive requirement for R-38 ceiling insulations is deemed to be met by R-30 insulation when the R-30 insulation extends over the wall top plate at eaves and when the insulation is at full loft and uncompressed over the wall top plate at eaves.  Similarly, R-38 insulation is recognized to satisfy the requirement for R-49 insulation when R-38 insulation extends over the wall top plate at eaves and when the insulation is at full loft and uncompressed over the wall top plate at eaves.*

Section N1102.2.3 Eave baffle.  This section indicates the requirement for baffles to be installed next to eave and soffit vents for vented attics using air permeable insulations.  The baffle can be any solid material, must extend to the top of the attic insulation, and must maintain an opening that is at least as large as the vent.*
Note that baffles should also be used with vented cathedral assemblies.

Section N1102.2.4 Access hatches and doors. Doors or hatches separating conditioned spaces from unconditioned spaces (such as attics and crawl spaces) must be weather-stripped and insulated to a level equivalent to that of surrounding assemblies.  When loose fill insulation is used, insulation dams are required around attic hatches.*

Section N1102.4 Air Leakage.  This section indicates that the building thermal envelope (as it is called in the IRC) must be sealed to limit infiltration and that it must be sealed in a manner that is durable allowing for differential expansion and contraction.*

*Due to copyright restrictions, exact code text is not provided. For specific code text, refer to the applicable code.

More Info.

Access to some references may require purchase from the publisher. While we continually update our database, links may have changed since posting. Please contact our webmaster if you find broken links.

Case Studies

  1. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: June, 2013

    Case study about one of three deep energy renovations of occupied affordable homes.

  2. Author(s): PNNL
    Organization(s): PNNL
    Publication Date: January, 2012

    Case study about an energy efficient retrofit project in hot-humid climates.

  3. Author(s): BSC
    Organization(s): BSC
    Publication Date: March, 2010

    Case study describing a retrofit project in the cold and very-cold climate zones.

  4. Author(s): CARB
    Organization(s): CARB
    Publication Date: November, 2013

    Case study exploring how using buried and/or encapsulated ducts can reduce duct thermal losses in existing homes.

  5. Author(s): IBACOS
    Organization(s): IBACOS
    Publication Date: May, 2014

    Case study describing a stand-off furring strategy that minimizes the physical connections to each existing wall stud, uses spray foam to encapsulate existing siding materials (including lead paint), and creates a vented rain screen assembly to promote drying.

References and Resources*

  1. Author(s): ICC
    Organization(s): ICC
    Publication Date: January, 2009

    Code establishing a baseline for energy efficiency by setting performance standards for the building envelope (defined as the boundary that separates heated/cooled air from unconditioned, outside air), mechanical systems, lighting systems and service water heating systems in homes and commercial businesses.

  2. Author(s): ICC
    Organization(s): ICC
    Publication Date: January, 2009

    Code for residential buildings that creates minimum regulations for one- and two-family dwellings of three stories or less. It brings together all building, plumbing, mechanical, fuel gas, energy and electrical provisions for one- and two-family residences.

  3. Author(s): ICC
    Organization(s): ICC
    Publication Date: January, 2012

    Code establishing a baseline for energy efficiency by setting performance standards for the building envelope (defined as the boundary that separates heated/cooled air from unconditioned, outside air), mechanical systems, lighting systems and service water heating systems in homes and commercial businesses.

  4. Author(s): ICC
    Organization(s): ICC
    Publication Date: January, 2012

    Code for residential buildings that creates minimum regulations for one- and two-family dwellings of three stories or less. It brings together all building, plumbing, mechanical, fuel gas, energy and electrical provisions for one- and two-family residences.

  5. Author(s): Lstiburek
    Organization(s): BSC
    Publication Date: February, 2010
    Document providing background and approach for the prep work necessary prior to adding attic insulation - focusing on combustion safety, ventilation for indoor air quality, and attic ventilation for durability.
  6. Author(s): Lstiburek
    Organization(s): BSC
    Publication Date: November, 2015
    Strategies to control ice dams from forming on residential buildings during winter.
  7. Author(s): EPA
    Organization(s): EPA
    Publication Date: January, 2015
    This page provides important information on how to protect yourself and your family if you suspect that you might have vermiculite insulation from Libby, Montana.
  8. Author(s): Lstiburek
    Organization(s): BSC
    Publication Date: October, 2006
    Report providing guidance about whether to construct a vented or unvented attic based on hygro-thermal zone.

Contributors to this Guide

The following authors and organizations contributed to the content in this Guide.

Building Science Corporation, lead for the Building Science Consortium (BSC), a DOE Building America Research Team

Last Updated: 11/30/2015

Mobile Field Kit

The Building America Field Kit allows you to save items to your profile for review or use on-site.