Patrick’s Barn: The Dirt-Cheap, High-R Building
You may recall my large purchase of salvaged polyiso insulation. After finishing the walls with two layers for a supertight R-21, I’m moving on to the rafter cavities, where I plan to put in three layers for R-31. If I still have material left over, I’ll install a fourth layer in the attic.
I think the inexpensive ($1500) polyiso board was one of our smartest construction decisions, but it does have drawbacks. It is very slow to install, for starters. A spray-foam crew could easily insulate the whole building in a few hours, but I’d guess we already have close to 30 hours into our insulating and air-sealing efforts. My guess is we have another day or two (at least) of finishing up. Cutting the 4×8 sheets to fit inside the rafter cavities is also slow and nasty work. The sheets cut like butter on the tablesaw, but the spinning blade through the fiberglass facing produces a lot of very itchy dust. A respirator is a must. But I think the drawbacks are easily tolerated for such an inexpensive wall with good thermal performance.
I’ve also been installing vinyl siding on the exterior. My wife helped me put up the pump jacks on the south wall, our highest elevation. That work is now done. I’m embarrassed to say I didn’t have a card in the camera when I snapped a photo of the staging at its maximum height with a stepladder on top. With a cleat nailed to the staging planks and the ladder tied to the closest collar tie with a rachet strap, I climbed that ladder perhaps a dozen or more times while siding the upper reaches of the gable. I’d be lying if I said I wasn’t scared, but it was all worth it when I was finally able to climb down, look up at the wall, and savor a beer.
You can read more about my barn here.
This is the first layer of insulation. You can see the building girts (horizontal framing members) in the photo. I already sealed the exterior when I installed the felt weather barrier. I'm also sealing the inside for extra insurance.
This is the second layer of foam. I'm sealing that, too. Not only does the extra spray foam stop air movement, but it does a great job of holding the foam in place. This gable wall with its 24-in.-on-center studs was the perfect place to use up scraps and offcuts. On most job sites, these small pieces would end up in the Dumpster. I credit my Scottish ancestry for my willingness to spend 3 or 4 hours insulating about 100 sq. ft. of wall.
I always remind people to listen to that little voice in their head, as I've ignored the voice just before an injury or bad decision. This is one of those occasions when I ignored the little voice. These 2x4s are for the pump jacks I'll use to side the south wall. Getting them home worked out fine, but I swore to myself and our creator that I wouldn't try anything like this again.
The pump jacks are supported at the top by a steel bracket, which I'm screwing to the sub fascia in this photo. A few minutes later, my wife carried the bottom of the post toward the building while I took the top up the ladder. Her job was harder, as it involved carrying most of the pole's weight, and she did it without complaint even with a cold that made her achy and stuffy. She's the best carpenter's helper I've ever had.
Here's the rig just before things got moving in earnest. I'm installing the battens and J-channel around the gable window. I used the window for material storage and accessing the stage. I hadn't been on pump jacks in 15 years and had forgotten how wobbly they are.