Green Dream Hits a Snag

The insulated panels are the perfect building material ... as long as they fit

Setting the First Roof Panels

John B. Carnett

We recently installed the panel roof system over the kitchen area and hit the first of our inevitable early-adopter glitches. The roof panels are 11 inches thick and much heavier than the wall panels, as they have much more embedded steel to carry both my green roof and the snow load here in upstate New York. The things are dense and required a serious effort for two to carry around. Even with all that beefiness, the engineer asked me to put a horizontal steel beam through the middle of the room for added support. The panels were supposed to meet at the beam and fit seamlessly together. The key words there: supposed to. Read on for the reality.

Center Beam Supports the Roof

John B. Carnett

The first two panels went together like a glove, but as we installed more panels it became harder to maintain a perfect fit in the middle and at the side walls. Each panel required more and more spray foam to both seal and glue the joint together. And getting both the perfect bit of glue and the panels in position was full of smacking and pushing. The issue was that each panel had to meet a side wall and also touch the other panel in the middle. In other words, they all had to be precisely the right size. They were not.

Filling the Gaps

If the panels don't quite line up, you just spray more foam to fill it in. Not ideal, but it works.John B. Carnett

We pushed one panel toward the middle and it would push the other toward the outside. If you were building with traditional 2x6-inch wood framing, you can make small adjustments in your framing to hide these kinds of fit up issues, but when your panels are precisely spec'd by an engineer and cut at the factory, well, you're out of luck.

I know being the first to use any technology comes with trade-offs, and I'd rather have a bit of fit-up trouble to get a roof with an R-value, a measure of thermal resistance, of 52—several times the typical roof. But that's little consolation when your arms are burning as you pound the umpteenth panel into place. Fortunately, the company is sending out its own team next week to do some panel remaking in the field. Then we should be back on track.