Raised Heel Trusses Allow for More Insulation

This is our first in a series of educational posts about energy efficient methods for building. All of our new projects use raised heel trusses to maximize the amount of insulation that can be installed in the attic. Historically, roofs were framed using rafters, joists and collar ties. Often, the lumber was undersized, which is why you see some roofs sagging. More recently, economies of scale and computer engineering have allowed pre-built standard trusses to replace the stick framing of the past. However, both of these have a downside because they don’t allow for much insulation at the edges of the home. Consequently, we use raised heel trusses on our new projects. The added cost runs about $200 to $400 per home.

According to the example in the Energy Trust of Oregon Best Practices Pocket Guide, there is a significant insulation difference between the standard and raised heel truss R49 vs. R41. “Figure 23 shows standard vs. raised heel trusses. R-49 insulation was installed in two 1050 sq. ft. attics. In the attic on the left, less insulation was installed due to space constraints at the wall-truss connection. Therefore, there are only 910 sq. ft. of R-49 insulation, the remaining 140 sq. ft. is insulated on average to R-20. The Area-Weighted R-Value for the standard truss left attic is reduced to R-41as calculated.”