Converting a flat roof to a pitched roof?
I’m in the process of remodeling my 1950s ranch house. I have a modified bitumen flat roof, which is about 15 years old. The roof is in okay shape right now, however it’s sloped incorrectly in about half the roof and has some ponding of a few inches most of the time. There has been some damage to the roof sheathing near the chimney in the past. The rest looks to be in good shape. I’d like to improve the roof and be able to add more insulation to the ceiling as the first part of my renovation. I’d like to get your opinions on the best way to improve the roof. Right now I am considering converting the flat roof to a hip roof with at least a 4/12 pitch.
I met with a contractor and he suggested putting trusses over the top of the existing roof assembly to achieve the pitch. He said a tear off of the membrane and ship lab sheathing wouldn’t be necessary. He would cut through the membrane and roof sheathing at the end of each rafter to blow cellulose between the sheathing and the ceiling below it (about 6 inches) and blow more cellulose on top of the sheathing and membrane. Right now the flat roof is vented through the sofits around the whole perimeter of the house. Vents would be added to the top of the roof. Would this set up cause moisture problems?
Thanks for any suggestions, let me know if I can provide more info.
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