Condensation forming inside wall cavity (zone 6)
I’m in the process of building a woodshop and recently noticed some condensation forming on the exterior sheathing behind the insulation in the unfinished utility room (see attached photos). The rest of the walls have taped drywall so I’m not worried about those areas but my original plan was to just put unpainted 1/2″ plywood on the walls in this room so I can easily remove them to access electrical, plumbing, etc.
The exterior side of this north-facing wall is a covered (future screened-in) porch currently just has the 3/4″ sanded plywood and does receive some blown in moisture. The plan next summer was to clad this wall in some shiplapped ash that we milled recently from trees harvested on the property.
I have 2 questions I wanted to solicit some opinions on:
1) Will the paper-faced insulation plus the plywood be a suitable vapor barrier to prevent this from happening over the long run (provided I unfold and staple the craft paper properly)? I can install 6-mil poly over the insulation behind the plywood if absolutely needed but it will prevent me from easily accessing this wall cavity in the future and I sort of expect to need to when I’m working on the porch side of this wall as my wife we will probably want to install some additional lighting, outlets, etc.
1B) If I do install poly over the insulation, do I need to pull out the insulation and dry everything out well first?
2) My original plan was to finish nail + PL the ash directly to the plywood to avoid exposed fasteners which would mean there would be no house wrap on this facade. Again, this is a covered porch that does receive a little blown moisture but less so when the screening goes in. The ash will be varnished for its protection but is it a mistake to not add Tyvek? If this were fully exposed I’m a big fan of installing siding over furring strips over house wrap to provide a drainage/drying plane for water that works its way through the siding but I’d like to avoid it here if possible for ease of cladding installation and the detailing around the door.
Edit: I’m also trying to make sense of why the moisture is forming in certain areas and not others and wanted to solicit some opinions on that as well. I’ve added a third photo that shows where the plywood joints are. I felt behind some additional areas and the moisture isn’t limited to these 3 bays but I didn’t pull everything out to try and map it or anything.
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