Advanced Framing: Insulated Corners

    Scope Images
    Image
    Advanced framing details include corners that are constructed with fewer studs or studs aligned so that insulation can be installed in the corner.
    Scope

    Construct framed walls using advanced framing details like insulated corners that reduce framing and thermal bridging and allow more space for insulation.

    • Construct corners with two studs or three studs aligned to allow more room for insulation along the exterior wall. 
    • Use drywall clips as needed to hold drywall in place.
    • ENERGY STAR requires that the space provided at the corner allow for at least R-6 of insulation (ENERGY STAR 2018). 

    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 Certified Homes, and Indoor airPLUS.

    Description

    Exterior wall corners are typically framed with three studs. The third stud generally only provides a nailing edge for interior gypsum board and its typical placement blocks off the wall cavity, preventing insulation from being installed. If the third stud can be eliminated, there is more room inside the wall for insulation. Drywall clips, a 1x nailing strip, or a recycled plastic nailing strip can be used to create a two-stud corner that still provides a surface on which to hang the drywall. Using drywall clips also reduces opportunities for drywall cracking and nail popping, frequent causes of builder callbacks.

    The designer should include the corner detail on building plans. It should be installed by the framer. If two-stud corners are used, they can be insulated by the insulation contractor. This task should be included in the contract for the appropriate trade, depending on the workflow at a specific job site. ENERGY STAR Version 3.0 requires that all exterior corners shall be constructed to allow access for the installation of ≥ R-6 insulation that extends to the exterior wall sheathing. See the Compliance tab for 2009 IECC-specified wall insulation levels.

    How to Insulate Corners

    Construct exterior corners to allow access for the installation of > R-6 insulation that extends to the exterior wall sheathing in one of the following ways:

    1. Construct a two-stud corner using a nailing strip or drywall clips, which allows the wall cavity at the corner to be insulated in sequence with the rest of the installation at full wall thickness.
    • When drywall clips are used, they should be installed above the level of the interior trim so trim nails will not interfere.
    • If installing trim, the noncoped trim piece should be installed first, against the drywall that bears on the clip, so that the coped trim piece can be nailed to the stud.
    • If rigid foam is used as the sheathing instead of OSB or another solid nailable sheathing, install a wood nailer strip behind the sheathing if necessary for attaching exterior trim or siding at the corner on the side that does not have a stud.
    Two-stud corner using drywall clips; detail shows nail placement for exterior trim.
    Figure 1. This side view shows drywall clips installed on studs at a two-stud corner (the second stud is not visible behind the first corner stud). The plan view in the detail shows the placement of nails for fastening exterior corner trim (Source: Building Science Corporation).

     

    Conventional three-stud corners leave a cavity that must be insulated by the framers—not good.
    Figure 2. Conventional three-stud corners leave a cavity that must be insulated by the framers—not good (Source: Building America Best Practices Series Volume 12: 40% Whole-House Energy Savings in the Cold and Very Cold Climates 2011). 

     

    The improved three-stud corner allows insulation to be installed later, in sequence.
    Figure 3. The improved three-stud corner allows insulation to be installed later, in sequence (Source: Building America Best Practices Series Volume 12: 40% Whole-House Energy Savings in the Cold and Very Cold Climates 2011). 

     

    Two-stud corners with drywall clips use the least wood and give the best thermal performance.
    Figure 4. Two-stud corners with drywall clips use the least wood and give the best thermal performance (Source: Building America Best Practices Series Volume 12: 40% Whole-House Energy Savings in the Cold and Very Cold Climates 2011). 

     

    Ensuring Success

    The quality of the insulation installation should be visually inspected by the site supervisor before the drywall is installed. It may be possible to detect heat loss at the corners of exterior walls with an infrared camera, if a sufficient temperature difference exists between the outside and the conditioned space of the house.

    Climate

    No climate specific information applies.

    Right and Wrong Images
    Image
    Wrong – Framing does not allow corner to be insulated
    Wrong – Framing does not allow corner to be insulated
    Image
    Right – Framing allows corner to be insulated
    Right – Framing allows corner to be insulated
    Image
    Wrong – Framing does not allow corner to be insulated
    Wrong – Framing does not allow corner to be insulated
    Image
    Right – Framing allows corner to be insulated
    Right – Framing allows corner to be insulated
    Image
    Wrong – Framing does not allow corner to be insulated
    Wrong – Framing does not allow corner to be insulated
    Image
    Wrong – Excessive framing will not allow corner to be insulated
    Wrong – Excessive framing will not allow corner to be insulated
    Image
    Right – Gap in framing will allow corner to be filled with insulation
    Right – Gap in framing will allow corner to be filled with insulation
    Image
    Right – This three studs in this corner are positioned to allow insulation against more of the exterior wall than standard three-stud corners.
    Right – This three studs in this corner are positioned to allow insulation against more of the exterior wall than standard three-stud corners.
    CAD
    CAD Files
    2-stud corner with drywall clips
    2-stud corner with drywall clips
    Download: DWG PDF
    2-stud corner with 1x4 backer
    2-stud corner with 1x4 backer
    Download: DWG PDF
    3-stud corner with rigid insulation
    3-stud corner with rigid insulation
    Download: DWG PDF
    Conceptual 3D advanced framing drawing
    Conceptual 3D advanced framing drawing
    Download: DWG PDF
    Conceptual 2 foot module house drawing
    Conceptual 2 foot module house drawing
    Download: DWG PDF
    Corner installed plywood or OSB as shear bracing
    Corner installed plywood or OSB as shear bracing
    Download: DWG PDF

    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, Version 3/3.1 (Rev. 09)

    National Rater Field Checklist

    Thermal Enclosure System.
    3. Reduced Thermal Bridging.
    3.4.3a Corners insulated ≥ R-6 to edge.22

    Footnote 22) All exterior corners shall be constructed to allow access for the installation of ≥ R-6 insulation that extends to the exterior wall sheathing. Examples of compliance options include standard-density insulation with alternative framing techniques, such as using three studs per corner, or high-density insulation (e.g., spray foam) with standard framing techniques.

    Please see the ENERGY STAR Certified Homes Implementation Timeline for the program version and revision currently applicable in in your state.

     

    DOE Zero Energy Ready Home (Revision 07)

    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 International Energy Conservation Code (IECC)

    Table 402.4.2 Air Barrier and Insulation Inspection Component Criteria, Walls: Corners, headers, narrow framing cavities, and rim joists are insulated.

    Table 402.4.2, Air barrier and thermal barrier: Exterior wall insulation is installed in substantial contact and continuous alignment with the air barrier. Air permeable insulation is not used as a sealing material.

    2012, 20152018, and 2021 IECC

    Table R402.4.1.1 Air Barrier and Insulation Installation, Walls: Corners, headers, and rim joists making up the thermal envelope are insulated.

    Table R402.4.1.1, Air barrier and thermal barrier: A continuous air barrier is installed in the building envelope including rim joists and exposed edges of insulation. Breaks or joints in the air barrier are sealed. Air permeable insulation is not used as a sealing material.

    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)

    Table N1102.4.2 Air Barrier and Insulation Inspection Component Criteria, Walls: Corners, headers, narrow framing cavities, and rim joists are insulated.

    Table N1102.4.2, Air barrier and thermal barrier: Exterior wall insulation is installed in substantial contact and continuous alignment with the air barrier. Air permeable insulation is not used as a sealing material.

    2012, 20152018, and 2021 IRC

    Table N1102.4.1.1 Air Barrier and Insulation Installation, Walls: Corners, headers, and rim joists making up the thermal envelope are insulated.

    Table N1102.4.1.1, Air barrier and thermal barrier: A continuous air barrier is installed in the building envelope including rim joists and exposed edges of insulation. Breaks or joints in the air barrier are sealed. Air permeable insulation is not used as a sealing material.

    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.

    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
    References and Resources*
    Author(s)
    U.S. Environmental Protection Agency
    Organization(s)
    EPA
    Publication Date
    Description
    Guide describing details that serve as a visual reference for each of the line items in the Thermal Enclosure System Rater Checklist.
    Author(s)
    NAHB,
    Southface Energy Institute,
    Oak Ridge National Laboratory,
    National Renewable Energy Laboratory
    Organization(s)
    NAHB,
    Southface Energy Institute,
    Oak Ridge National Laboratory,
    National Renewable Energy Laboratory
    Publication Date
    Description
    Information sheet about advanced wall framing.
    Author(s)
    Baechler,
    Gilbride,
    Hefty,
    Cole,
    Love
    Organization(s)
    Pacific Northwest National Laboratory,
    Oak Ridge National Laboratory
    Publication Date
    Description
    Guide describing measures that builders in the cold and very cold climates can take to build homes that have whole-house energy savings of 40% over the Building America benchmark with no added overall costs for consumers.
    Author(s)
    Lstiburek
    Organization(s)
    Building Science Corporation,
    BSC
    Publication Date
    Description
    Report detaining advanced framing techniques, including discussion of cost and energy savings.
    Author(s)
    APA - The Engineered Wood Association
    Organization(s)
    APA - The Engineered Wood Association
    Publication Date
    Description
    Detailed guide to advanced framing, a system of construction framing techniques designed to optimize material usage and increase energy efficiency.
    *For non-dated media, such as websites, the date listed is the date accessed.
    Contributors to this Guide

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

    Building Science Measures
    Building Science-to-Sales Translator

    2-Stud Corner w/Drywall Clips = High-Efficiency Corner Framing

    Image(s)
    Technical Description

    Traditionally built homes use three or more studs in exterior wall corners leaving minimal space for insulation, resulting in  thermal losses. By only using two studs and a clip to help hold the drywall, high-efficiency corner framing allows for insulation in the corners of a home and reduces heat loss. This in turn minimizes cold spots at corners while saving both energy and cost. It also helps minimize corner cracking because the two sheets of drywall that meet at the corner are effectively attached to the same stud, eliminating differential movement.

    High-Efficiency Corner Framing
    Sales Message

    High-efficiency corner framing reduces the heat loss and gain though structural framing. What this means to you is less wasted energy along with enhanced comfort and quiet. Knowing there is one opportunity during construction to lock in quality construction, wouldn’t you agree advanced thermal protection is a great investment?

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