The Green Dream Gets a Third Floor

I can’t believe it, but the entire box is now up. All the wall and roof panels have been installed. As you may recall the second floor was a bit of a learning curve for everyone, but when it came to the last level, everything went together as expected. LightShip Group, the firm making the panels, took all the field experiences that we had with the first install, went back to the shop and turned out 100 percent perfect panels for my third floor walls and roof. Click the gallery for shots of the third floor and it’s curved roof section going up, and see more details about the build after the jump.

Here are a few highlights from the final push:

• Light Ship eliminated the “C” channels that had been on all the interior walls and instead used a two-inch angle. That really helped speed up the install process: We no longer had to cut channel in the field. Rather, we just had to unscrew and flip around the angle that was already on the panel from the factory. It was a brilliant solution, but it was too late for all my exterior walls that have the “C” channel. Any cold that hits the outside of the channel goes right under the panel and into the interior with no thermal break. I intend to fix this by running a strip of Aspen Aerogel along the entire interior where the channel enters the house to create a thermal break. Like I say, lessons learned.

• Lightship also provided pre-cut metal corner connections for all the panels this time around. That saved a bunch of time as we could just slap down the metal and go without having to stop to cut raw material. My chop saw can finally rest.

• They also designed an in-house crane hoist bracket that allowed multi-wall panels to be connected on the ground then lifted into position as single units.

• My third floor roof is 11 inches thick and it carries itself all the way down the roof to the north vertical wall over a curved radius. That not only gives me an incredibly high R-50 insulation rating for the roof, but also for the back wall. It’s an amazing feeling to stand in a corner of a building that is under construction and feel warm.

• I elected to use the same panel material in four-inch thickness for my interior walls. This allowed everything to go up at the same time and was a really effective way to deal with the ceiling curve connecting to the interior walls. You can imagine how long it would take to frame that kind of radius with typical 2×4 framing methods. I ended up with very tight walls between the roof and the interior, which will help control not just temperature but sound as well for a very peaceful bedroom.

• During the third-floor install I started counting the number of cans of 12 oz spray foam that we used. It took more than 81 cans to connect all the panels. Lesson learned: Remember to include spray foam in your budget!

• Just as soon as the Kama panels were installed, we began getting Zip board on the roof and exposed walls. The curved corner on the roof was too tight for the zip board so we used 1/4-inch AC plywood in two offset layers then covered it with a waterproof membrane, which matched up perfectly to the Zip Board.

I’m looking forward to getting the doors, windows and metal roof on next. In the meantime, check out the gallery of the third floor going up here.

John B. Carnett, PopSci’s_ staff photographer, is using the latest green technology to build his dream home. Follow along as the project progresses on his Green Dream blog: popsci.com/green-dream_