I’ve written several posts about how to insulate basements, How To Insulate Basement Walls and Basement Insulation. One of the best ways I know how to insulate a basement is using a combination of polystyrene foam board insulation and spray-in-place cellulose insulation.
I get so many emails and questions about how to properly insulate a basement. For me there are really two options. Probably the best option out there is to use a closed cell spray foam insulation sprayed directly onto the concrete foundation walls and a framed stud wall. However, spray foam insulation is really expensive and depending on where you live it may be hard to find an installer. That’s why I like the approach I’ve outlined here using a combination of foam board insulation and cellulose.
How To Insulate Basement Walls
- First of all it’s very important to make sure your basement walls are structurally sound and any cracks that are present are properly sealed.
- Install a 1″ layer of polystyrene foam board insulation from the slab up to the top of concrete wall. Use an adhesive that’s rated for use with foam board. It’s also important to seal all the joints with a tape like Tyvek tape or similar.
- Frame a 2×4 wall in front of the foam board insulation. I like to install a piece of composite decking below the wood bottom plate. This ensure that if there ever is some water behind the wall that it won’t wick up into the framing and drywall.
- Hire a qualified NuWool cellulose insulation installer to use spray-in-place cellulose to fill the 2×4 framed wall.
You can see in the photo all the steps involved. The nice thing about the cellulose is it’s fire retardant and mold resistant. The foam board and taped joints help keep moisture from entering the basement from the damp cold concrete walls. Once the cellulose has dried a bit we’ll be installing a layer of gypsum board to ensure that the cellulose doesn’t fall out of the stud bays as it continues to dry.