Green Dream Hits a Snag

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

By John B. Carnett Posted 09.25.2009 at 10:30 am 5 Comments

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.

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5 Comments

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mattman_83

10/03/09 at 6:36 am

John,

Sorry to double-post (also mentioned this in the geothermal section), but I am rushing to plan the window cutouts for our sips. Any news on the "build your own high efficiency windows" article? I am hoping to build both these and my own doors (using the sips cutouts, thinned down a bit). Any info would be great.

Thanks,
Matt
mattman_83@hotmail.com

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John Carnett

10/05/09 at 10:41 am

Hi Matt- My next story in the magazine will feature my aluminum windows and doors- It will also be posted here once it hits the newsstand. I found a small yet highly focused company that spent the last two years coming up with a much better and cheaper solution for aluminum windows- Better than my original DIY idea- Right now all you need to know is that you can go ahead and design any cut out that you wish in your SIP's as the windows are all custom- not stock- so whatever you want they can do and the price was the same as high quality mainstream stock windows... just make sure that you have included the proper engineered lumber in your sip package

John

Staff Photographer
Popular Science Magazine

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Greenteck

10/06/09 at 9:49 am

Yes, there were some fit-up problems but once the fascia caps were installed and the punchlist items were attended to the first floor walls and roofs came out GREAT. In construction – especially with new technology – the statement isn’t IF there are issues, it’s WHEN there are issues. The real metric is how they are resolved. In this case small tweaks were needed prior to fascia cap installation…tweaks done; caps installed…energy savings commence!

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John Carnett

10/06/09 at 7:57 pm

I'm currently in production of an HD movie that covers the panel building process- this movie will contain time lapse of the build process (a picture every 8 minutes) as well as various panel building moments- I expect to launch the first installment next week here on the site- John

Staff Photographer
Popular Science Magazine

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cwolf88

10/13/09 at 11:54 am

1. I built a stress skin house. The panel ends had to be cut, then foam scooped out, then joined with a 2x6 or 2x8 (plus foam). Very labor intensive. Later after a roof leak, I found the panels had separated significantly despite glue, foam, and nails. If I had to do it again, I'd use steel framing, then just bolt the panels to it.

2. Lifting the roof panels: we just drilled a hole in the middle, then inserted an eye bolt over circular saw blade then lifted with a crane.

3. The other interesting technology is foamed concrete houses.

4. Don't ever get windows with plastic sheets inside the glass.

5. The life cycle problem with houses is maintenance. Avoid anything that will require painting or that can rot. Painting your house would be stunningly expensive.