Plot: Our new roof is going on, and our master carpenter talks to roofing contractor Mark Mulloy about the system: decking, bitumen membrane covering every surface from eave to ridge, a three-dimensional nylon mesh to allow air to flow beneath the shingles, and finally the shingles themselves - pressure-treated southern yellow pine with a 50-year transferable warranty. Tom shows Steve how to cut studs quickly when building a partition wall beneath a bowed ceiling, while our master carpenter takes viewers to the Bend, Oregon, factory where our new windows are being made