This weekend I removed the torn insulation and even a few of the ceiling tiles to get a better idea of how the room is insulated. Here are a few pics:
There are no vents/opening to outside air in my rafter bays. It's just wood.
It looks like there's an air channel. There are no baffles but there's a gap between the insulation and roof deck that leads to the attic opening. Not sure how effective this is since there are no soffit vents.
This is where I removed the built-in dresser to access the space behind the knee wall. You can see the rafter bay where I removed the insulation. I believe joecaption
is correct about the cardboard - looks like it's used to hold the insulation in place/prevent it from sagging.
The outside of my house has no overhang to install soffit vents. The gutter is flush with the aluminum siding. I also noted one of the gable vents in the pic.
Here you can see the ridge vent that runs across the entire roof. There are gable vents on the right and left sides of the house.
I didn't take photos where I removed the ceiling tiles but there are a few rafter bays that are wider than the others and the insulation doesn't fill the entire bay which leaves nothing between the under side of the roof and the bedroom ceiling. No matter what I do I believe adding insulation to areas such as these will keep the room cooler in the summer.
My big question is, since I don't have soffit vents, do I still need to have air channels leading to the attic? Will the gable and ridge vents move air through the rafter bays even though they don't have a source of external air? The goal is to keep the room cooler in the summer and hopefully warmer in the winter. I'm more concerned about preventing mold/mildew than ice-dams (I rake my roof after every snow storm to prevent/minimize them). My roof is fairly new, about 7 years old, so I don't want to tear part of it off to install soffits. I saw products such as SmartVent
but they still require removing shingles, cutting into the roofing then replacing shingles... looks costly and not DIY friendly.
My current idea is to first seal as many gaps as I can with expanding foam. Then, on the lower portion of the roof (the part below the attic), I'm thinking I should keep air space in the rafter bays since it was there originally by installing baffles. I'll then put in Roxul, cover with a vapor barrier, and install drywall. Directly above the ceiling I'll use thicker Roxul since I'm not constrained by the height of the rafters. I was also debating adding a radiant heat barrier over the insulation to help with the heat in the summer.
How does that sound? All comments are welcome. I know insulating older Cape's is difficult and there are many theories on what's correct. I love working with my hands and this is project is as much a learning experience as it is improving the temperature in the room.