1923 Balloon Frame – Insulation Questions
As the title suggests, I recently purchased a 1923 house with balloon frame construction and have a plethora of insulation/air sealing questions. I’ll try to be succinct as I know this has been asked before, but I’m trying to do the best for my specific house.
To start, we had an energy audit performed which yielded obvious results….this thing is leaky. The contractor followed up with a spray foam insulation quote, which included applications along the foundation rim joist and attic roof rafters.
With the weather becoming increasingly cold this winter, we began to feel drafts (more like breezes) throughout the house, but most noticeably along a specific exterior wall. To investigate, I began tearing out drywall in the basement along the wall in question and was surprised to find mortar between the floor joists. The rim joist in this specific area was not drafty at all, so I assume spray foaming would not accomplish much.
I consulted a friend who builds/restores very high end homes and he was against spray foaming the rim joist in my specific situation. His reasoning included the potential for water to become trapped along the rim joist (it’s above grade) and the uncertainty of water ingress along the foundation. There is interior drainage along most of the foundation (except in the wall i started tearing up) which drains to 3 (!) sump pumps, so water was an issue in the past but I have not exposed the foundation anywhere else. He did suggest that I could use rock wool in the rim joist cavities if I decided to rip all of the walls open.
Back to the draft along the foundation. I traced this to an attached greenhouse and air sealed as best as possible. There’s also a nearby cold storage room beneath the front porch which was dug out by a previous owner. Both the cold storage room and greenhouse are very, very leaky. Yes, the layout of this basement is insane.
My current plan of action is to remove the existing drywall along the cold storage room and greenhouse, reframe, air seal, and add rigid foam board as insulation. I don’t believe water ingress is an issue along these walls as they are both kind of “interior” walls now.
My questions are as follows:
1. Am I on the right track as far as reframing and insulating the walls along the cold storage room and greenhouse? Can I spray foam along the stone foundation in these areas or should I consult with a mason about repointing, etc? The idea, at least in my head, is to isolate the greenhouse and cold storage room as exterior zones and stop air from infiltrating into the basement.
2. Anyone else concerned with spray foam applications along rim joists in a house such as mine? I’ve been researching and going into the weeds on this, but I agree with the concerns of my builder friend about spray foam. How am I ever going to know about a water issue behind the foam, especially if I finish the basement completely?
3. I don’t think I’ll ever get the basement air right, but should I be worried about ventilation issues as i air seal and/or insulate? No hvac runs down there, but I will likely add a mini split head to the basement in the near future. I ran a dehumidifier 24/7 when we bought the place in October and it would fill up with water every other day or so. I assume it will be very humid down there in the summer, and the dehumidifier will probably be sucking warm air from outside into this space if I don’t tighten up the walls.
4. I’m confused by the balloon frame construction. In the attached rim joist photo, you can see two studs between the floor joists, which I assume run all the way to the attic. If these make up the interior side of my walls, I don’t think I can access the wall cavity from the basement. I assumed the air drafts I feel along the exterior walls of my house were due to air infiltration from the basement creeping into the wall cavities. Am I wrong on that? Should I be looking at possible openings on my exterior (currently vinyl siding over original wood)? I’m really confused by this.
I’ve attached photos of the rim joist, foundation exposure, and a 1st grade level drawing of the basement layout in this area. I can attach more photos if they help explain my situation better. Thanks again!
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