Basement Insulation Tips Video
Hi, I'm Tim Carter and I'm here at a new home construction site in New Hampshire. We are down in the basement to talk a little bit about basement insulation. Look at this.
This is the poured basement foundation wall. It has damp-proofing and even water-proofing on the other side. But concrete can hold water for a long time. And in the Northeast, the ground gets cold and can actually freeze almost four-feet down. This causes the concrete basement wall to almost become an ice-cube. This radiates the cold inside, so you want to stop that.
Two things. First, if you insulation using a solid foam (in this case, 2-inch of rigid closed-cell foam insulation), it acts as a really great water barrier. And it does it from both directions. In case water vapor comes from inside the basement and would touch the bare concrete wall, it would form condensation. That would be the fuel for mold and mildew. If the concrete has water in it, this type of insulation will stop the water vapor getting into the basement.
Secondly, this type of insulation should go all the way from the slab to the top of the concrete. Once the 2x4 wall studs are installed tight against the insulation, fiberglass insulation will be added between the studs. But first, be sure to use a special tape to tape over the joints where two pieces of the rigid foam meet. The tape will be made by the foam insulation manufacturer so that it will stick to their foam.
One last thing, this particular rigid foam insulation sheets comes tongued-and-grooved. This interlocks with the next piece of foam, creating a tighter seal. Insulate your basement this way when you build or remodel.