Possible metal over metal installation

Guest User
1/1/2006
I have a 50+ year-old barn with it's original tin roof. The roof is not on plywood but on strips of wood that attach to rafters and is in pretty good shape (it doesn't leak). I am thinking about turning the upstairs of the barn into living space and like the look of the ceiling as-is. I need to insulate the space and I was wondering if any product is out there that I could install over the existing roof. I'm trying to do this on a budget so cost is a concern. The upstairs of the barn is 40' x 80' and I am planning to turn about 1/2 of this into finished space. The roof rises about 8 ft. over a 20 ft. run. After reading your articles I'm scared of condensation, so advice on this would also be appreciated. Thank you.
Allan Reid
Dura-Loc Roofing Systems, Inc.
1/2/2006
Don't be scared, just build it to code. Residential occupancy will create moisture which needs to be controlled. This means interior sealed air barrier, insulation, ventilation and moisture barrier. My suggestion would be to spray foam insulation into the cavity, This will provide the interior air barrier if done correctly and the insulation. Then choose a new roof system that can install on strapping. Strap the roof vertically over the rafters fastening down into them and in between it required with a 1 1/2" board, the strap harizontally to accept the roof metal. Use vented strips at the eave and ridge. The existing metal may act as youe exterior moisture barrier but I would install a good quality reinforced membrane over the vertical strapping as extra precaution. Take car in locating roof penetrations correctly. Choose a system and ajust accordingly trying to keep them higher up and centred on the panels if possible and install sleeves before yoy spray foam.
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