5 proven ways to optimize framing

4. Insulated Headers

Advanced framing headers offer increased energy efficiency by replacing framing material with space for cavity insulation inside the header. Advanced framing headers are sized for the loads they carry and are often installed in single plies rather than double, as shown in Figure 5. Sizing for single-ply lumber headers is covered prescriptively in the 2012 IRC Table R602.7.1.

FIGURE 5

Single-ply engineered wood headers may be calculated based on tributary loads applied to the header. To do so, determine the live load and total load in pounds per linear foot and refer to a published standard, such as the American Wood Council’s Wood Frame Construction Manual (WFCM) for One- and Two-Family Dwellings. Headers at openings in non-load-bearing walls are not required (Figure 6). The top of the opening can typically be framed with a flatwise member the same dimension as the wall studs.

FIGURE 6

Site-built wood structural panel box headers are another simple code-prescribed header solution that provides full-depth cavity insulation. They may be used as load-bearing headers in exterior wall construction, when built in accordance with 2012 IRC Figure R602.7.2 Typical Wood Structural Panel Box Header Construction and Table R602.7.2 Maximum Spans for Wood Structural Panel Box Headers.

Typically built with 15/32 Performance Category wood structural panel sheathing installed over minimum 2x4 framing, wood structural panel box headers provide more cavity insulation space than dimensional lumber headers. Types of wood structural panel box headers are shown in Figure 7.

FIGURE 7

Wood structural panels can be installed on one side (panel installed on the exterior side) or both sides of the header. In most cases, one-sided is the best option (if meeting the structural requirements specified in the IRC Table) because installation of interior finishes may be impaired by wood structural panels on the interior side of the wall. On the exterior side, wood structural panel box headers are a perfect complement to continuous wood structural panel wall sheathing, because the sheathing for the header also acts as part of the continuous sheathing.

The 2012 IRC Table R602.7.2 allows a 15-inch, one-sided wood structural panel box header to span 4-foot-wide openings for homes up to 28 feet wide, and 3-foot-wide or narrower openings for homes up to 32 feet wide in single-story construction with a clear-span truss roof or two-story construction with the floor and roof supported by interior bearing walls. Openings up to 4 feet wide require only a single stud at the sides of the rough opening, eliminating the need for jack studs, thereby providing another opportunity to replace framing members with cavity insulation.

Where nominal ceiling height is 8 feet or higher, an overall height of 15 inches allows for installation of 6-foot, 8-inch interior and exterior doors.