Vapor retarder? Upper floor gut, main floor remains.
Working on a 1905 residential house in Marine 4C that does not have a vapor retarder on the walls or ceiling. The upper floor is being completely gutted, with new heating and air conditioning.
The roof will be foamed at the rafters/sheathing (I’m aware of the open/closed cell discussion and will address accordingly), but this question is for the walls. Typically we just put up PVA paint on partial remodels and call it a day, but since this is a full gut we have more options. The siding is wood lap on sheathing, so not vented. Code says we need at least class II.
I am thinking Intello (class II) on all interior second floor walls (and ceiling if we use open cell at the roof). The question is: will this screw anything on the main floor given the old house will have a different permeability on each floor?
For the roof – do conditioned CLOSED cell attics also need dehumidification?
TIA
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Replies
TIA,
I can't think of why varied wall permeability would make any difference.
Whether the attic will need de-humidification depends on how it is conditioned. If you are exchanging air with the rest of the house it should track the humidity in the living spaces below pretty closely. If you are just supplying heat it might need some help.