I am converted a existing 2 car garage into a wood shop. It is an attached garage, with an open crawl space leading to the roof. Previous owners left the existing roof and put a new roof a few ft. above the old one, with 1 basement window. My problem is I live in the colder climate of the USA, and want to run a Nipco heater run from propane, but the exhaust smell gets into the home, wife not happy. I plan on finishing off the shop with insulation and 1/2" CDX, but need to keep the vapors or smell out of the home. Any one have any questions, I am a DIY'er.