Brick veneer soffit gap: block and drill weep holes?
Common scenario, but I searched the internet for hours and somehow couldn’t find this answer. I’m very slowly working on insulating and sealing our 40s brick veneer house, Cape 2.5 story with slate roof and no overhangs.
There is no dedicated soffit ventilation – what was there before was just rough gaps between the fascia board and the brick. There are gable vents. Existing insulation was R10 worth of black fiberglass between the rafters. There’s some discoloration but no frank mold/rot thankfully. Sheathing is planks with some sort of plastic/tar between them and the slates.
Gutters were destroyed by ice dams, so I’m having a roofer come and replace them, with new fascia boards that have dedicated vent spaces between them and the brick. The hope is that this ‘soffit ventilation’ will help keep things dry after installing thick insulation.
I tried to seal the attic floor and kneewalls but eventually gave up. On one side there’s a dropped ceiling for a shower, a utility chase to the basement, ducts (with asbestos wrap of course), and pipes. All the hits. So I’m doing a vented cathedral roof using mineral wool, Tyvek as wind washing/air sealing barrier, on the exterior, membrain on the interior (the mineral wool is furred out to R=60) and a little closed cell foam on the interior for sealing and at the eaves where space is at a premium.
It’s very difficult to access the gap between the wall sheathing and the top plate in the eaves (see picture). My understanding is this air leak is the #1 cause of ice dams, but I worry about closing off the ability of the brick to dry (inward solar drive issue). Conversely, I also worry about unsealed leaks in the exterior walls below entering this channel and contributing to warm, humid air hitting the roof sheathing.
If I bug the roofers, I could maybe get on the scaffold and do some work when the fascia board is off, but that’s asking a lot and the work is still tricky and prone to failure. What about blocking this off with foam board or garbage bags stuffed with insulation, foaming up to the baffle, and then drilling vent holes in the vertical mortar underneath the soffit? Is this a terrible plan?
PS there are currently no weep holes in the bricks near ground level. I’m considering making some but may defer to a mason.
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