My house was built in the early 1900s (St. Louis, MO) with balloon framing and a hip roof with dormers on the north and south side. The upstairs/attic is finished with “knee walls”, but the knee walls are 7’ high and have access doors on the east and west side. Also worth noting that the ceiling is flat and not vaulted. I traced out the living space in the image below. I just installed fully vented soffits on the east and west side (marked with yellow line). The north side, south side, and both dormers have non-vented aluminum soffits installed over solid wood but replacing the north and south side with fully vented soffits is a project scheduled for next weekend. There was R-11 faced fiberglass stapled to the rafters when I bought the home, but that has all been removed aside the southeast corner (drywalled over – no access currently).
Here is my grand plan:
- Radiant barrier stapled to rafters from top plate to highest access point in attic side of knee walls,
- Rigid foam insulation on attic side of knee walls
- Cover the foam insulation with radiant barrier (I bought way too much radiant barrier).
- Install a power ventilator near the ridge, which should in theory, pull air from the vented soffits as well as the rest of the unconditioned attic space.
- Eventually cut access holes in the living space ceiling so I can blow in insulation and cover with more radiant barrier.
My question is, should I vent the dormers soffits as well? Or would that “short circuit” the airflow from the soffits?
As a guy that likes the cold (and doesn’t have a wife or kids to answer to), I really don’t care about retaining heat in the winter. The reason I’m doing all of this is because the upstairs is a bedroom that turns into a literal oven during the summer that required window A/C units to be running constantly just to maintain ~75 degree temps up there. The upstairs living space does have two central air registers and a return, but they can’t compete with the 100+ degree attic temps. I realize that a power vent will probably suck out conditioned air, but I care more about comfort than electric bills at this point.
If anyone has any insight or can provide guidance it would be much appreciated. This hip roof/dormers/knee wall/balloon framing question is so insanely specific that I haven’t been able to find any concrete answers elsewhere. I’ve caused myself too many headaches trying to research this issue that I’ve turned into a broken man and need a professional’s assistance.
If you’ve read down this far, feel free to send me an invoice for your time.