“Energy Savings Start With The Framing.” As energy codes become more stringent and homeowners demand higher performing homes, designers are looking at innovative ways to improve the efficacy of their building envelopes. Insulated headers can really help to improve the R-value and provide wall cavity space for insulation. ASHRAE estimates that at least 4 percent of the wall assembly consists of headers. If 4 percent of your wall is not properly insulated, your energy envelope will not be performing at its best.
From the APA: “In a 2×6 wall, a solid wood header has a total R-value of 6.88; a double 2x dimension lumber insulated header can have an R-value starting at 13.8. Depending on the type of insulation used to fill the cavity behind the header and the thickness of the structural wood header itself that number can climb even higher.”
Designers often use headers that have a far higher load-bearing capacity than is necessary i.e. 2x10s instead of 2x6s that would carry the load, or the framer uses 2x10s because it’s close.
But, with a little careful planning, you can design a home with both structural performance and high R-values. This can be achieved by carefully calculating the load requirements and the headers needed to meet that need and then using the remaining space for insulation. Openings in walls running parallel to the floor joists don’t carry the same load as those perpendicular to the joists.
Insulated headers Types
Most designers use the same headers for every job and size the headers to fill the space. But, when the headers are sized for load capacity, the extra space can be filled with cavity insulation. Here are a few examples:
Single-ply Headers: Here a single wood member is used to support loads over open spaces creating a cavity space that can be insulated. Here is an example from the APA: “When a single 2x header (1-1/2-inch thick) is used in a 3-1/2-inch-thick wall, 2 inches of cavity insulation can be added to net a total header area R-value of 10 or greater.”
Double-ply headers: Double-ply headers use two wood members and so there is less space for insulation. However, you can still utilize some of the cavity for insulation. From the APA: “When a double 2x header (3-inch thick) is used in a 3-1/2-inch wall, 1/2 inch of cavity insulation can be added. If 1/2-inch EPS rigid board insulation or polyisocyanurate is used to fill the open area, the insulation value of the header increases from R4.38 to R5.8 and R6.8, respectively.”