I just bought a 1935 house in Mississippi, and I'm dealing with a kitchen/pantry/laundry extension that has a low-slope roof. There's no attic, no vents, and no insulation, which has led to the ceiling hitting 100°F already in May. I found out I don't have interior access to the ceiling cavity, so I'm considering removing the 18' fascia board and blowing in dense-packed cellulose insulation from the outside. My plan is to first remove the fascia, then seal any gaps with foam or caulk, blow the insulation into the rafter bays, and finally reinstall the fascia. I'm aware that it's an unvented cavity, so I have to be cautious about moisture risks if it's not air-sealed. I'm also unsure whether the rafter bays are open or blocked. I'm looking for any advice on this method. Has anyone tried this approach, or do you have better suggestions?
1 Answer
Getting a proper dense pack from the outside could be a challenge, but it’s worth a shot. Ideally, spraying foam from the interior would be the best fix, and then you could just re-drywall the ceiling. If you want to go for exterior insulation, be prepared for the possibility of needing to redo parts of the roof. But hey, if you’re trying to avoid cutting the ceiling, I think your plan is a decent backup! Just be cautious about sealing everything well before blowing in the cellulose.
I see where you’re coming from! I totally agree that spray foam is the gold standard, but if you can manage to get a good seal with dense-packed cellulose, it might still make a significant difference. Just remember, even a less-than-perfect fill is way better than leaving it hot and uninsulated.