A few years ago I built a cement addition to my metal pole barn that is 4'X4' with a poured concrete floor. I put my wood burner inside and made an opening in my barn for access. 6:00am Thanksgiving I noticed sparks coming over the roof and ran out to find the wood and shingle roof on my little addition was on fire---SO WAS THE ROOF ON MY BARN! I managed to salvage my barn, thank god ! The fire chief said the wood roof self combusted and that it should have happened sooner. Plans this summer are for angle iron trusses (homemade) and sheetmetal roof--NO COMBUSTIBLES.I almost lost everything...please be careful.I will always burn wood cause there is no better heat in my opinion.