Retrofit basement insulation old house Chicago
Hello, looking for some guidance as we are in planning/research phase of basement finish. Sorry for wall of text, trying to give enough detail.
Chicago, zone 5 1910 balloon frame 2 story 1300sq ft house with walk up attic and half below ground basement.
Exterior is vinyl siding->1/4 in foamboard->another layer of vinyl?->poly sheet->1/2 in fiberboard? (house used to have asphalt shingle side)->3/4 t&g sheathing. Front of house still has layer of asphalt siding underneath.
(attached picture because some layers hard to figure out)
Interior of upstairs is 2×4 plaster and lath (minus 4 rooms that have been demoed and insulated per zone and drywalled). New rooms have fiberglass. We added blown in cellulose to one bedroom with plaster and will do others after blocking is adding in basement.
Basement is a half basement poured concrete walls 20×30 room. 1 addition of a cold storage room off the back with walkout steps (addressed this in another post). 1 ft above grade exposed, 3 ft below grade. Walls are about 13 in thick (possibly originally 12 inchs plus interior parging coats) Interior concrete has also been painted in last 60 years. We have some seepage from cracks during heavy rains that we are having addressed by foundation repair company at areas where downspouts failed/some settling occurred. None are new as previous patches were made probably in the 60’s. Grading and downspouts have been addressed. Basement floor is painted concrete graded to center floor drain. No interior or exterior drain system.
2×4 balloon studs sit on a 2×6 sill plate with no capillary break. Currently sill plates are hidden behind a ledger board on majority of walls minus into cold storage room.
Stud walls in basement plastered on lath, painted, furred out with plywood and then veneer flooring strips added as paneling. Stud bays are empty. I’ll attach photo of a 1 empty stud bay.
Trying to do this smart but also correct. I have tried to read everything on here that I can find relevant. The biggest issue is the drafts and cold walls on first floor and also cold basement. I have caulked and sealed at every window and trim board in entire house.
We would like a clean space that is warmer and more even with rest of house. Hoping to add 3 interior walls to close off mechanical area and laundry room and have a flex area. I don’t need bottom concrete enclosed if that isn’t wise though we would prefer to in at least the flex area living space.
For the concrete walls we are considering either repainting in bright white drylock (some areas may need new parging) and leaving uninsulated or insulating them as per article on insulating basement space.
1. We need to add fireblocking to studs to prevent air movement from basement up to attic so plan to remove plaster from area within floor joists of 1st floor to get to stud pockets. If possible, we will stuff some fiberglass up the void to area by first floor baseboards then attach fireblock 2×4 and spray foam to seal. This will also open pocket into basement studs bays.
2. Would pour-in-place spray foam be a good option for these basement voids? We are considering this because it seems wasteful to tear down walls just to rebuild. Also dealing with lead paint. Is cellulose an option or too risky above a sill plate without barrier?
3. Should we be very concerned to insulate against sill plate in this situation since we do not have sill capillary break? I do not think it would be feasible to jack house to add barrier since we recently had almost every wall skim coated upstairs. I have exposed some sections of the side of a sill plate and there appears no rot.
4. Is there a smarter way to do this that is also efficient/green?
Any ideas or opinions would be great.
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