Foam sheets on underside of this ceiling to stop ice dams?
One room on the east side of the building has a cathedral ceiling with NO insulation. The ceiling is made from 2×6 T&G spanning 8 Ft on center, with the ends supported by walls and the center by a truss. The other rooms have an attic.
We would like to add insulation to the underside of the cathedral ceiling and are considering:
a) Two layers of 2”polyiso
b) Two layers of ¾ polyiso
c) 1×6 carsiding
(1) Do I nail the first layer to the ceiling or then to each other to hold in place?
(2) Should I use canned foam (what type) to seal the edges?
(3) Should I tape the seams on each layer or just the final layer(metal faced tape)?
(4) How should the carsiding will be mounted under the foam
1×4 screwed to the ceiling through the foam or
2×6 24 on center and along the walls ( creates a thermal bridge but gives a way to mount lights)
(5) how can I mount lights and fans?
Any help would be appreciated
this building is a nature center in SE WI.
and are faced with high energy costs and ice dams.
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