posted 1 hour ago
Situation: Tiny home in a cold/frigid climate for year round living. Desiring natural building techniques, metal is ok. Roof pitch limited to around 6:12. Cathedral ceiling preferred but attic is ok if needed.
The walls will be tongue and groove wood on the inside, planer shavings, borax and maybe clay slip as the insulation (4" on walls, 6" on floor and roof), and board and batten or t&g exterior boards.
The floor will be wood boards on 6" floor joists with the same insulation as in the walls. The exposed surface underneath will be metal roofing, partially for mouse prevention.
In a cathedral ceiling situation, the ceiling will be wood boards and the same insulation. My simple thought is to use metal roofing and pack the shavings fully between the ceiling and roofing. But, I'm worried about condensation on the underside of the metal getting the insulation wet and leading to rot/mold. If I leave an air gap, the condensation will likely still form and some may run down hill and exit but some undoubtedly would get into the insulation. I've heard that if the dew point is reached "in" the insulation you don't have anything to worry about but I'm not sure if that's with styrofoam or any kind of insulation.
In an attic situation, I could do ceiling boards, insulation and then more boards on top to contain the insulation and block airflow. Then have a well vented attic with a metal roof. Would that greatly reduce the condensation to the point of not having to worry? Plus it would drip on boards instead of insulation so it probably would evaporate?
Alternately, is there a natural sort of vapor barrier I could use to keep humid house air from reaching the roof metal? Perhaps rosin paper or single ply cardboard?
Alternately, is there another form of roofing that would not have the condensation problem? Thatch isn't a solution for my area/expertise. Wood shingles might be...
I'm hoping the floor wouldn't have the same problem....
Thanks!!!
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