• You're one step from joining Insulation Forum – Home Energy Efficiency, Soundproofing & Materials.
    Create a free account to post, follow threads, and never miss an update.  Sign up free →

Insulating a 1985 basement

theb00m

New member
Joined
Sep 21, 2025
Messages
3
I’m planning to insulate the basement in our 1985 house, so I poured concrete with about 7.5 feet of full height walls. I’m leaning toward using rigid foam panels on the walls.

To keep the budget and workload reasonable I’m wondering if it makes sense to leave the floor as is for now. From what I understand the walls are usually the bigger source of heat loss compared to the slab, but I’m not sure if skipping the floor will undercut the benefit of insulating the walls. The house is in Ontario and I have no idea if the slab has any insulation under it. Has anyone here tackled a similar project? Just wanted to know if it’s worth the extra effort to address the floor too. Thanks!
 
Heat loss from a slab depends a lot on whether it’s insulated underneath, which 1980s builds usually weren’t. But wall surface area is bigger and more exposed, so starting with rigid foam panels there is still the right call. Floor insulation is comfort, not priority.
 
I’m planning to insulate the basement in our 1985 house, so I poured concrete with about 7.5 feet of full height walls. I’m leaning toward using rigid foam panels on the walls.

To keep the budget and workload reasonable I’m wondering if it makes sense to leave the floor as is for now. From what I understand the walls are usually the bigger source of heat loss compared to the slab, but I’m not sure if skipping the floor will undercut the benefit of insulating the walls. The house is in Ontario and I have no idea if the slab has any insulation under it. Has anyone here tackled a similar project? Just wanted to know if it’s worth the extra effort to address the floor too. Thanks!
Walls first is the right call actually, that's where most heat escapes. The slab will feel cold underfoot, but it's not bleeding heat like uninsulated walls do. A 1985 build likely has no insulation under it, but you can address that later if needed, just so the walls now, you'll see the benefit immediately
 
Back
Top