The Green Dream Home Gets a Crucial Second Skin
An extra panel system called ZIP saves the day
Building this house has been a constant learning experience, and today was no exception. My original plan was to build the walls from special insulated structural panels from Kama-Eebs, add some simple “X” braces to control shear, and throw on some housewrap before attaching my siding. And that would have been the cheapest and most ideal solution, but the more I looked at the final Kama panels installed the more I began to question the wisdom of that idea.
During install, we ran into some fit-up issues and the panels were now full of metal plates and caps that were added in various areas at different elevations as part of the field repairs to get the system to all fit together. As hard as the Kama repair team worked to get the roof to line up with the walls, things were still not flush. If I just threw housewrap over my panels, the shiplap siding — the part you’ll actually be able to see — would never sit correctly. I needed something to create a smooth, uniform surface and I needed it not to cost a fortune. Then I discovered the amazing ZIP panel system.
The ZIP system is a combination engineered-wood panel and protective covering (with special tape for the seams) that would give me a 7/16-inch thick structural wall panel, moisture resistance and an air barrier all in one lightweight sheet. Just attach the $10 panels to my walls, tape the joints and that’s it. I was sold.
Smooth Zip wall
I ordered the wall sheathing (they also make a roof version) and we started throwing it on. Part of the appeal of the ZIP panels is the quick install, but it took us three days to get 2,600 square feet up because every panel had to be cut to fit and screwed onto the Kama system. The screwing itself was the most time consuming part. Imagine driving thousands of machine screws with an electric drill, screws breaking off in the wall, screws hitting screws already in the wall. If we had been attaching it to a standard timber frame, we could have just used nail guns, which would have been a lot faster.
The other timesuck was cutting the 4-by-8-foot ZIP panels so that the screws would hit the steel in the kama panels, which were not uniform. Neither of these things were ZIP’s fault — just the result of our ongoing experiment here. Once we got the panels all screwed on, we used the special zip tape to go over all the joints.
Zip panel close-up
After the chaos of the past couple of weeks, I’m thrilled to say I ended up with walls that are now smooth and very tight. Just touching the final result is impressive when compared to typical housewrap over sheathing, which always felt to like gift wrap on a present: very easy to have a bad fit, a tear, a leak. The ZIP panels were idiot proof and a great way to take care of my Kama issues. Like I said, every step an adventure in this house.
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_