Advanced Framing: Minimal Framing at Doors and Windows
Construct framed walls using advanced framing details like minimal framing at windows and doors to reduce thermal bridging and allow more space for insulation.
- Limit framing to a maximum of one pair of king studs per window opening.
- Limit framing to a maximum of one pair of jack studs per window opening to support the header and window sill.
- Install additional jack studs only as needed for structural support and cripple studs only as needed to maintain on-center spacing of studs.
- Limit framing to necessary structural requirements for each door opening.
See the Compliance Tab for related codes and standards, and criteria to meet national programs such as ENERGY STAR Certified Homes, DOE’s Zero Energy Ready Home program, and EPA’s Indoor airPLUS.
In stud-framed walls, extra studs are often installed around windows and doors, even when they are not needed to bear structural loads. Window and door openings should have no more than one pair of king studs, one pair of jack studs, and the minimum number of cripple studs needed to maintain on-center spacing of studs. Adding more studs than necessary wastes lumber and reduces the wall’s thermal resistance because the lumber blocks cavity space that could be filled with insulation and because each stud represents a thermal bridge that can transfer heat between the interior and exterior of the building.
Building scientists estimate that standard stud construction may use 5% to 10% more board feet of lumber than necessary and add up to 30% more pieces of lumber than needed (Lstiburek 2010). By using advanced framing techniques, builders can reduce the amount of lumber used and save money as well. Building Science Corporation found savings of up to $1,000 per home in materials and labor were possible for production builders who used a combination of several advanced framing techniques (Lstiburek and Grin 2010). Advanced framing techniques should be specified in the framer’s contract. For more about advanced framing, see Minimum Wall Studs.
The framing pieces that surround windows and doors include king, jack, and cripple studs, headers, and sills. The full-length stud on each side of a door or window is called a king stud. A header is a piece of framing installed horizontally directly above the door or window opening and extending to the king stud on each side of the opening. The header rests on jack studs that are nailed in place next to the king stud on each side of the opening; jack studs extend to the bottom plate of the wall. A saddle or sill is another horizontal piece that goes under the window opening and is nailed to the inside of each jack stud. Because typical stud spacing is 16- or 24-inch on center and most windows and doors are wider than this, cripple studs are installed below window openings from the sill to the bottom plate in the location where a common stud would have been if the space had not been left open to accommodate the door or window. Depending on the header height, cripples are sometimes located above the window extending from the header to the top plate.
How to Install Minimal Framing at Doors and Windows
1. Design homes on a two-foot grid with 2x6 studs spaced 24 inches on-center (See Minimum Wall Studs). Align windows and doors with this two-foot stud spacing to reduce the number of extra king studs needed.
2. Hang insulated headers with metal hangers instead of jack studs.
3. Attach 2x2s to the outside edge of the kings studs if nailers are needed to attach trim or siding, rather than using extra king studs, if “nailable” OSB sheathing is not installed.
Advanced framing details should be specified in the construction plans (i.e., framing elevations should be provided) and these plans should be reviewed by the site supervisor and lead framer. The construction supervisor should ensure that framing crews are knowledgeable of or trained in advanced framing techniques. The framing should be visually inspected by the site supervisor before the drywall is installed.
No climate specific information applies.
ENERGY STAR Certified Homes (Version 3/3.1, Revision 08), Rater Field Checklist
Thermal Enclosure System:
3. Reduced Thermal Bridging:
3.4.3c Framing limited at all windows & doors to one pair of king studs, plus one pair of jack studs per window opening to support the header and sill.
ENERGY STAR Revision 08 requirements are required for homes permitted starting 07/01/2016.
Exhibit 1: Mandatory Requirements. Certified under ENERGY STAR Qualified Homes Version 3.
North American Fenestration Standard/Specification for Windows, Doors, and Skylights. Available from AAMA. This is a voluntary standard/specification that covers requirements for the following components for new construction and retrofits: single and dual windows, single and dual side-hinged door systems, sliding doors, tubular daylighting devices, and unit skylights.
Door Gasketing and Edge Seal Systems. Available from ANSI. This standard sets performance and installation of gasketing systems applied to doors and/or frames. It includes definitions, general information, and tests.
Standard Practice for Installation of Exterior Windows, Doors and Skylights. Available from ASTM. The standard covers fenestration product installation from pre-installation through post-installation procedures in new and existing construction.
This topic is not specifically addressed in the 2009 IECC.
This topic is not specifically addressed in the 2009 IRC.
This topic is not specifically addressed in the 2012 IECC.
This topic is not specifically addressed in the 2012 IRC.
Reduced Wall Framing = High-Efficiency Wall Framing