Scope
Retrofit an exterior wall and/or attic to provide continuous air sealing as follows:
- Connect the top of the wall air control layer to the perimeter of the roof/ceiling assembly air control layer and add insulation at this critical juncture to ensure continuity of the air control layer and a consistent thermal control layer.
- Inspect the roof and wall framing to verify existing conditions and develop specific detailing for treating the eave area.
- Verify that roof cladding, underlayment, and eave flashing provide adequate protection from rain water. Repair if needed.
- Install exterior and interior (framing cavity) insulation to levels that meet or exceed the current adopted building and energy codes.
Improvements to the air sealing at the attic-wall transition area can be made as a stand-alone retrofit project, as part of an upgrade to the attic insulation, as part of an effort to convert a vented attic to an unvented conditioned attic, as part of an exterior wall retrofit, or in preparation for an exterior wall retrofit.
See the Compliance Tab for related codes and standards requirements, and criteria to meet national programs such as DOE’s Zero Energy Ready Home program, ENERGY STAR Single-Family New Homes, and Indoor airPLUS.
Description
Where the roof meets the wall is a common source of air leakage in older homes. The transition of air control is both critical and difficult at this roof-wall intersection. Continuous air control at the top of the building is critical to performance because the difference between interior and exterior air pressure during the heating season tends to be the greatest at the top of the building in the attic. This pressure difference, called the stack effect, is the driving force behind air leakage (see BSD-014: Air Flow Control in Buildings). This air barrier connection is crucial both for unvented attics, where the connection is to the sloped roof air barrier/insulation plane, and vented attics, where the connection is to the ceiling plane at the floor of the attic.
Implementing uninterrupted air control is complicated by the geometry of the roof overhang, by the transition of the air control layer from one component to another, and by the roof framing (protruding rafter tails). Effective continuity of the air control layer relies on both (a) understanding the airtight connections needed between the wall and roof/ceiling assembly and (b) careful implementation and workmanship of these connections.
There are several ways to minimize air leakage at the attic eaves depending on whether the attic is vented or unvented and/or sloped. Figures 1 and 2 show an unvented roof assembly with closed-cell spray foam insulation at the underside of the roof deck. At the eave (Figure 1), a filler sheathing piece is installed at the top of the wall (in line with the existing board sheathing), with a continuous strip of fully adhered air control membrane lapped onto the existing wall air control layer. Two strips of rigid foam insulation are installed at the top of the wall, tight up against the roof eave, as backing for closed-cell spray foam. The outermost layer is extended up to the roof sheathing (notched around the rafters); alternately, the rigid foam insulation strips can be terminated at the bottom of the rafters and spray foam insulation installed around the framing. At the rake (Figure 2), attic closed-cell spray foam insulation is extended to the rake edge, and sealed to the rafter/blocking at the top of the wall, to the top plate, and to the inside face of the existing wall sheathing. No work is done on the exterior with this detail. For more information on insulating the underside of an existing home’s roof deck with spray foam, see the guide Below Deck Spray Foam Insulation for Existing Roofs.
Figures 3 and 4 illustrate an unvented roof assembly retrofitted with exterior insulating sheathing and insulation installed to the underside of the roof deck. For more information on this roof insulation approach see the guide Above Deck Rigid Foam Insulation for Existing Roofs. At the eave (Figure 3), the top edge of the existing house wrap or building paper is taped to the sheathing with sheathing tape. A strip of rigid foam is installed in line with the floor joists as backing for spray foam. Closed-cell spray foam insulation then makes air barrier connections from (a) the underside of the roof sheathing to (b) the floor sheathing to (c) inside the face of the rigid insulation backing to (d) the inside face of existing wall sheathing. At the rake (Figure 4), a filler piece of sheathing is installed at the top of the wall. The top edge of the existing house wrap or building paper is taped to the sheathing; the wall air control layer is connected to the roof air control layer using a strip of fully adhered transition membrane.
Figures 5 and 6 show a vented roof assembly retrofitted with closed-cell spray foam and blown fibrous insulation installed at the attic floor and a rigid insulation rafter baffle attached to nailers under the rafters. At the eave (Figure 5), a sheathing filler piece is installed at the top of the wall (in line with the existing wall sheathing); it is bedded in sealant at the wall top plate, to provide an air barrier connection. The filler piece then receives a continuous strip of fully adhered air control membrane lapped onto the existing wall air control layer. To provide additional insulation at the wall-roof connection, a strip of rigid foam insulation is installed at the top of the wall and notched around the rafters. Alternately, the rigid foam insulation strips can be terminated at the bottom of the rafters, and spray foam insulation can be installed around the framing. In the roof assembly at the rake (Figure 6), the attic insulation is extended onto the inside face of the existing wall sheathing and no work is done on the exterior. For more information on retrofitting the attic insulation by adding spray foam above the ceiling deck, see the guide Spray Foam Insulation Applied to Existing Attic Floor.
If the retrofit project includes (or will include in the future) the installation of rigid foam sheathing on the exterior walls, an extension of the overhangs at the eaves and/or rakes may be needed, because the upgraded walls will be thicker than standard construction. If this extension lowers the elevation of the soffit at the eaves, it may conflict with the existing window head heights or head trim. This needs to be taken into account during planning for the overall renovation.
How to Air Seal and Insulate at Roof Eaves
- Inspect the integrity of the roof system (roofing membrane or shingles). If water damage or active leaks are found, d. do not proceed until repairs are performed.
- Inspect the structural integrity of the roof. Check the roof framing for any deficiencies, rot, insect damage, etc. Do not proceed until repairs are performed. Based on the findings, revise the roof assembly and review specific detailing as needed. Follow the minimum requirements of the current local building code regarding the wood roof framing construction.
- Install a filler piece of wall sheathing at the top of the wall, above the existing board sheathing; and notched to fit around and between the rafters; air seal around the edges. Install rigid foam insulation strip(s) tight up against the roof eave and notch around the rafters. Alternately, terminate the strips at the bottom of the rafters and spray foam around them (see Figure 1 and Figure 5). If the attic has floor boards, as shown in Figure 3, remove flooring at the eaves, block the openings between the ceiling joists with rigid foam. Use the rigid foam as a backer for spray foam installed to air seal and insulate the ceiling joist bays and the eaves.
- Install a continuous fully adhered air control membrane to seal the connection between the filler piece and existing wall sheathing. Lap the membrane onto the existing wall air control layer (see Figure 1 and 5). Alternately, tape the top edge of the existing house wrap or building paper with sheathing tape to the existing wall sheathing to provide an adequate air control layer (see Figure 3).
- Install closed-cell spray foam at the underside of the roof sheathing and extend into the eave (see Figure 1 and 3). Alternately, install closed-cell spray foam at the attic floor, at the bottom of the rafter baffle, and extend into the eave (see Figure 5). The area should be free of debris and dust prior to spraying for adequate adhesion.
Success
Inspect the existing roof framing and the roofing membrane or shingles for any deficiencies and make any corrections if necessary.
If the retrofit project includes (or will include in the future) the installation of rigid foam sheathing on the exterior walls, an extension of the overhangs at the eaves and/or rakes may be needed, because the retrofit walls will be thicker than standard construction. If this extension lowers the elevation of the soffit at the eaves, it may conflict with the existing window head heights or head trim. This needs to be taken into account during planning for the overall retrofit.
Apply spray foam insulation to a clean surface to ensure proper adhesion. The R-value of the spray foam insulation in the eave should be equivalent to the R-value of the wall insulation to control ice dams.
Climate
The map in Figure 1 shows the climate zones for states that have adopted energy codes equivalent to the International Energy Conservation Code (IECC) 2009, 12, 15, and 18. The map in Figure 2 shows the climate zones for states that have adopted energy codes equivalent to the IECC 2021. Climate zone-specific requirements specified in the IECC are shown in the Compliance Tab of this guide.
Figure 1. Climate Zone Map from IECC 2009, 12, 15, and 18. (Source: 2012 IECC)
Figure 2. Climate Zone Map from IECC 2021. (Source: 2021 IECC)
Water Management
In cold climates (zones 5 and higher), install self-adhered membrane over the roof sheathing at the eaves from the edge of the roof line to > 2 feet up the roof deck from the interior plane of the exterior wall. (See the guide WM.3.4: Heavy Membranes at Eaves in Cold Climates.)
Thermal Enclosure
The roof 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.
The design should be based on the minimum requirements for the currently adopted building code and energy code, respectively. Table 1 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 roof assemblies.
Table 1. Attic Insulation Requirements in the 2009 and 2012 IECC. (Source: 2009 IECC and 2012 IECC)
If an unvented roof design is selected, using a hybrid of air-impermeable insulation (rigid foam or spray foam) and fibrous fill (air-permeable insulation), it is vital to maintain a sufficient ratio between the two to control condensation. In colder climate zones, the amount of air-impermeable insulation needed to maintain the sheathing temperature increases. Table 2 provides information on minimum levels of air-impermeable insulation for condensation control specified in Table R806.4 Insulation for Condensation Control of the 2009 IRC (ICC 2009a) and Table R806.5 Insulation for Condensation Control of the 2012 IRC (2012a).
Table 2. Insulation required for Condensation Control in the 2009 and 2012 IRC. (Source: 2009 IRC and 2012 IRC)
Training
Compliance
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 Single-Family New Homes, Version 3/3.1 (Rev. 11)
ENERGY STAR Single-Family New Homes requires that ceiling, wall, floor, and slab insulation levels meet or exceed those specified in the 2009 International Energy Conservation Code (IECC) with some alternatives and exceptions, and achieve Grade 1 installation per RESNET Standards (see 2009 and 2012 IECC Code Level Insulation – ENERGY STAR Requirements and Insulation Installation (RESNET Grade 1). 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 or 2015 IECC. Visit the U.S. DOE Building Energy Codes Program to see what code has been adopted in each state.
National Rater Design Review Checklist
3. High-Performance Insulation.
3.1 Specified ceiling, wall, floor, and slab insulation levels comply with one of the following options:
3.1.1 Meets or exceeds 2009 IECC levels5, 6, 7 OR;
3.1.2 Achieves ≤ 133% of the total UA resulting from the U-factors in 2009 IECC Table 402.1.3, per guidance in Footnote 5d, AND specified home infiltration does not exceed the following:6, 7
- 3 ACH50 in CZs 1, 2
- 2.5 ACH50 in CZs 3, 4
- 2 ACH50 in CZs 5, 6, 7
- 1.5 ACH50 in CZ 8
Footnote 5) Specified levels shall meet or exceed the component insulation levels in 2009 IECC Table 402.1.1. The following exceptions apply:
a. Steel-frame ceilings, walls, and floors shall meet the insulation levels of 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 in. on center. This exception shall not apply if the alternative calculations in d) are used;
b. 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;
c. 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 sq. ft. or 20% of the total insulated ceiling area, whichever is less. This exemption shall not apply if the alternative calculations in d) are used;
d. 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 performance of all components (i.e., ceilings, walls, floors, slabs, and fenestration) can be traded off using the UA approach. Note that Items 3.1 through 3.3 of the National Rater Field Checklist shall be met 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.
Footnote 6) Consistent with the 2009 IECC, slab edge insulation is only required for slab-on-grade floors with a floor surface less than 12 inches below grade. Slab insulation shall extend to the top of the slab to provide a complete thermal break. If the top edge of the insulation is installed between the exterior wall and the edge of the interior slab, it shall be permitted to be cut at a 45-degree angle away from the exterior wall. Alternatively, the thermal break is permitted to be created using ≥ R-3 rigid insulation on top of an existing slab (e.g., in a home undergoing a gut rehabilitation). In such cases, up to 10% of the slab surface is permitted to not be insulated (e.g., for sleepers, for sill plates). Insulation installed on top of slab shall be covered by a durable floor surface (e.g., hardwood, tile, carpet).
Footnote 7) Where an insulated wall separates a garage, patio, porch, or other unconditioned space from the conditioned space of the house, slab insulation shall also be installed at this interface to provide a thermal break between the conditioned and unconditioned slab. Where specific details cannot meet this requirement, partners shall provide the detail to EPA to request an exemption prior to the home’s certification. EPA will compile exempted details and work with industry to develop feasible details for use in future revisions to the program. A list of currently exempted details is available at: energystar.gov/slabedge.
Please see the ENERGY STAR Single-Family New Homes Implementation Timeline for the program version and revision currently applicable in your state.
DOE Zero Energy Ready Home (Revision 07)
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.
Exhibit 1 Mandatory Requirements.
Exhibit 1, Item 1) Certified under the ENERGY STAR Qualified Homes Program or the ENERGY STAR Multifamily New Construction Program.
Exhibit 2, Item 2) Ceiling, wall, floor, and slab insulation shall meet or exceed 2015 IECC levels and achieve Grade 1 installation, per RESNET standards.
2009-2021 IECC and IRC Insulation Requirements Table
The minimum insulation requirements for ceilings, walls, floors, and foundations in new homes, as listed in the 2009, 2012, 2015, 2018, and 2021 IECC and IRC, can be found in this table.
2009 International Energy Conservation Code (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 402.2.2 Ceilings without attic spaces. Where the prescriptive requirements would require more than R-30 insulation but the roof/ceiling configuration cannot accommodate the insulation level indicated by the prescriptive requirements, R-30 is the minimum insulation requirement. This reduced insulation requirement is limited to the lesser of 500 square feet or 20% of the total insulated ceiling area.
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.
2012, 2015, 2018, and 2021 IECC
Section R101.4.3 (R501.1.1/R503.1.1 in 2015 and 2018 IECC) 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 (R503.2 in 2015 and 2018 IECC) 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 (R402.1.2 in 2015 and 2018 IECC) 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. In the 2021 IECC, this requirement is extended to R-60 insulation: Where R-60 insulation is required, installing R-49 over 100 percent of the ceiling are requiring insulation shall satisfy the requirement for R-60 insulation wherever the full height of uncompressed R-49 insulation extends over the wall top plate at the eaves.
Section R402.2.2 Ceilings without attic spaces. Where the prescriptive requirements would require more than R-30 insulation but the roof/ceiling configuration cannot accommodate the insulation level indicated by the prescriptive requirements, R-30 is the minimum insulation requirement. This reduced insulation requirement is limited to the lesser of 500 square feet or 20% of the total insulated ceiling area.
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. The 2021 IECC notes that the baffle shall be installed to the outer edge of the exterior wall top plate in order to provide maximum space for attic insulation coverage over the top plate. Baffles shall be continuously installed to prevent ventilation air in the eave soffit from bypassing the baffle.
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.
Retrofit: 2009, 2012, 2015, 2018, and 2021 IECC
Section R101.4.3 (in 2009 and 2012). Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with this code. (See code for additional requirements and exceptions.)
Chapter 5 (in 2015, 2018, 2021). The provisions of this chapter shall control the alteration, repair, addition, and change of occupancy of existing buildings and structures.
2009 International Residential Code (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 R806.4 Unvented attic assemblies. This section outlines the conditions for unvented attic/roof assemblies. Note that table R806.4 indicates the amount of insulation above the roof deck or air impermeable insulation below the roof deck required for condensation control assuming minimum required total insulation as indicated in Section N1102 Building Thermal Envelope. Higher R-value assemblies will require a proportionally larger amount of air impermeable insulation below the roof deck or insulation above the roof deck for condensation control.
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 Building Thermal Envelope. Table N1102.1 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 N1102.2.2 Ceilings without attic spaces. Where the prescriptive requirements would require more than R-30 insulation but the roof/ceiling configuration cannot accommodate the insulation level indicated by the prescriptive requirements, R-30 is the minimum insulation requirement. This reduced insulation requirement is limited to the lesser of 500 square feet or 20% of the total insulated ceiling area.
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.
Appendix J, Section 501.6 (AJ109.6 in 2021 IRC), 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 R806.5.
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 R806.5 Unvented attic assemblies. This section outlines the conditions for unvented attic/roof assemblies. Note that table R806.5 indicates the amount of insulation above the roof deck or air impermeable insulation below the roof deck required for condensation control assuming minimum required total insulation as indicated in Section N1102 Building Thermal Envelope. Higher R-value assemblies will require a proportionally larger amount of air impermeable insulation below the roof deck or insulation above the roof deck for condensation control.
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 Building Thermal Envelope. Table N1102.1.1 (N1102.1.2 in 2015 and 2018 IRC) 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. In the 2021 IRC, this requirement is extended to R-60 insulation: Where R-60 insulation is required, installing R-49 over 100 percent of the ceiling are requiring insulation shall satisfy the requirement for R-60 insulation wherever the full height of uncompressed R-49 insulation extends over the wall top plate at the eaves.
Section N1102.2.2 Ceilings without attic spaces. Where the prescriptive requirements would require more than R-30 insulation but the roof/ceiling configuration cannot accommodate the insulation level indicated by the prescriptive requirements, R-30 is the minimum insulation requirement. This reduced insulation requirement is limited to the lesser of 500 square feet or 20% of the total insulated ceiling area.
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. The 2021 IRC notes that the baffle shall be installed to the outer edge of the exterior wall top plate in order to provide maximum space for attic insulation coverage over the top plate. Baffles shall be continuously installed to prevent ventilation air in the eave soffit from bypassing the baffle.
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.
Retrofit: 2009, 2012, 2015, 2018, and 2021 IRC
Section R102.7.1 Additions, alterations, or repairs. Additions, alterations, renovations, or repairs shall conform to the provisions of this code, without requiring the unaltered portions of the existing building to comply with the requirements of this code, unless otherwise stated. (See code for additional requirements and exceptions.)
Appendix J regulates the repair, renovation, alteration, and reconstruction of existing buildings and is intended to encourage their continued safe use.
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Tight Air Sealed Home = Comprehensive Draft Protection
Poorly air-sealed homes are less comfortable and cost more to maintain because they provide a pathway for drafts, cold spots, moisture, and insects into the home. Comprehensive draft protection includes a continuous air barrier around the whole house along with caulking and sealing in all holes and cracks. This includes around wiring, plumbing, ducts, and flues; where wall framing meets flooring; around windows; where drywall meets top plates and sill plates; where rim joists meet foundation walls and subfloors; etc. Spray foam insulation can be used at rim joists, floors above unconditioned space, and in attics to insulate and air seal at the same time.
Sales Message
Comprehensive draft protection minimizes air flow that can undermine a complete high-performance insulation system. What this means for you is less wasted energy along with enhanced comfort, health, quiet, and durability. Wouldn’t you agree it would be a shame to only get a partial return on your investment in advanced insulation?