I'm reaching out to gather some insights on the best approach to insulating my basement walls. We're currently planning a drainage project that involves excavating down to the footing. As part of this work, I'll be adding insulation to the basement, which is still unfinished. The plan is to use rigid foam for the insulation. I'm debating whether it would be more beneficial to insulate the exterior walls instead, which would save me the hassle of emptying out my packed basement full of tools and shelves. Anyone have thoughts on whether exterior or interior insulation is the better choice?
2 Answers
In a perfect scenario, exterior insulation is the way to go. If you fully excavate, ensure the walls are clean, and then add a waterproof membrane, it can really make a difference. After that, you could either go with a dimpled mat and exterior foam board or just traditional foam board covered with a protective layer. Just keep in mind that covering that foam above grade is important to prevent damage. Retrofitting might be more of a hassle than starting fresh, but a waterproofed exterior with interior foam could end up being a solid solution.
Totally get where you're coming from! If you're already digging and waterproofing, adding insulation to those outer walls might not be a huge extra step. It could save you from the giant task of moving everything out of your basement, especially since you’re using that space as a workshop. But make sure to have a chat with your contractor too to get the best advice for your situation!