The Construction of a High Performance Home: Week 6

By Tim Biebel | March 20, 2017 |

With the roof framing completed and the waterproof membrane in place, the focus has turned to finishing the interior framing so the electricians and plumbers can move in and begin their work. Once that’s completed, the crew will move back outside and complete a few minor framing items, like the two car garage.

Now that the building is up in the construction of a high performance home, I have some visuals to help explain a few of the energy details we like to do. The first is simple and adds next to nothing in the overall cost of a project. This involves the “heel height” of the truss. The heel height is the distance from the top of the wall to top of the sloped part of the truss.

Designing a 20” heel height will allow the insulation to extend all the way to the exterior of the wall at a uniform depth. A traditional truss design would have forced the insulation to taper to a lesser depth as it got closer to the exterior wall. An energy heel height is a simple design that can be incorporated into the house and will pay dividends forever.

The next detail I’d like to discuss is the energy seal on the ceiling. We use a product called Intello Plus that acts as an air barrier yet allows moisture to escape the insulation cavity if needed. We have been using the product for a couple of years now and have been impressed with the its air sealing capabilities. In fact, our tightest house yet utilized the Intello membrane.

If you look close at the pictures below, you’ll notice that we put up the membrane and strapping on the bottom side of the trusses BEFORE we framed any interior walls. This allows for a much better seal than if we cut the membrane to fit the ceilings of each individual room.

Not everyone likes this approach. The subcontractors that need to access the ceiling give us dirty looks when we tell them, “We did it again.” It makes their work a little more time-consuming for sure, but the product is better in the end, so it’s worth it. They will need to puncture the membrane to run wires and vent pipes, but air sealing a few holes is much easier than trying to seal around every interior wall joint.

There you have it! One simple design feature that creates a better insulated envelope, and one simple step to make for a better air seal at the ceiling. Maybe you can implement them if you decide to build a house some day!

Click here to read week 5 update.

Click here to read week 7 update.

Here are a few more pictures: