We used the same spruce two-by-six tongue-and-groove boards for the roof deck (sunroom ceiling) as we used for the floor. The most difficult part was tearing up a couple of feet of the earth roof on the house, so that we could marry the new roof to the old. I was pleased that the new material — from Russia — was almost identical to the lumber Fd used in the original roof, which was from Quebec. So, once the rafters had been extended, and the old gutter and drip edge removed, Anna and I were able to install the roof deck very quickly indeed, about two days. The work was easier than the floor because 1) we didn’t have to fit the first plank to a cordwood wall, 2) there were only two — large — facets instead of three smaller ones, 3) we were nailing to five-by-eights instead of four-by-tens and 4) we could let all the boards run long and trim the east and west overhangs with one single straight cut. With regard to 4), I let the tongue-and-groove planks overhang eight inches on the east and west walls. More would have been nice, but I was concerned about going too far out with cantilevered planking, considering that the earth roof, soaking wet with snow, can weigh 185 pounds per square foot (903 kilos per square meter).