Since the late 1960s, most houses have been built with engineered trusses (click on the link for more information than you need) instead of traditional rafters. Trusses offer greater spans to open up our interiors with great rooms, require less time and labor to erect, and provides a more uniform pitch to the roof, which may not seem important to you, but your roofer loves it.
Early truss systems resembled a triangle with a bunch of triangles inside the outside one. The problem that we ran into, from an energy usage standpoint, were those skinny angles at the ends of the truss. Often, there was not sufficient room to get an adequate amount of insulation into the space. I see a fair number of homes with shadowing on the ceiling at the outside edges of the rooms from precisely this.
A 1970s Engineered Truss
Note how skinny it is at the low edge. Not much room for insulation.
When energy was really cheap (raise your hand if you can remember $.25 gasoline!), this was not a big priority. Today, with more expensive energy and an improved awareness on how to heat and cool our homes efficiently, what happens on that edge is important. One solution was to re-design the truss. Meet the raised-heel truss.
The raised-heel truss
Raised-heel trusses are engineered to provide enough space for the insulation. By design, they are taller than older truss designs at the point where they cross the wall. This section, called the heel, intersects at the perimeter wall and lifts the top chord of the truss. From my research, it looks like the energy-saving qualities of the raised-heel were not the primary reason they were developed, though. Initially, the were built to match roof lines and increase curb appeal. Go figure . . .
Even though the cost for these trusses are not substantially higher than with other truss systems, I still don’t see that many of them. When I do, it’s good news for my clients!
(A quick note on the video - I shot it in an attic while hanging from the framing - it might not sound smooth and polished.)