A House Size Sweater, Rain Jacket, and Roof

So a couple of years ago I stumbled upon a group of building science nerds. These guys hangout at greenbuildingadvisor,com, greenbuildingtalk.com and buildingsciencecorp.com, they play with high efficient building systems.  Using simple building principles like high air tightness, high levels of insulation, and proper ventilation, you can cut the energy use of a home  50-70%.  So I decided to experiment with some of their design ideas on my house to see how they worked.

so I started off with improving the air tightness of the building envelope. so after I put up the OSB sheathing, I taped all the seems with 3M’s All Weather Flashing Tape. The point of this is to cut down all the drafts through the house.

After taping all the OSB joints. I put a “sweater” of recycled foam insulation, over the exterior of the house. this just helps improve the overall insulation R-value of the wall.

After the insulation was in place, I wrapped the foam with house wrap, then used pressure treated 1x3s to hold the assembly all together, the 1×3 strapping is screwed through the foam into the wall studs with 5 inch long screws. And if you think installing 5 inch screws in 30 degree weather is difficult, you’d be correct.

I used recycled polyiso foam that was removed from the roof of warehouses, the foam is in good enough shape for what i’m using it for, even though it was stained with some mildew. to be on the safe side, I sprayed both sides with fungicide, and let the foam dry out before installing it on the house.

My roof rafters were a bit too shallow to hold enough insulation to meet code. so I ended up building what is called an over-roof, where you add part of your insulation to the top of your roof deck, then add a layer of OSB and then your roofing material. It seemed to work well, though it makes the roof line look a bit fat.

My brother and brother-in-law came over and gave me a hand installing the metal roof panels.

So far so good.

Up next Windows, and Siding.


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