Insulating Part of the Basement

From what I’ve been reading online, there seems to be a general trend that’s moving people away from traditional fiberglass (pink stuff) insulation and moving them towards either spray foam insulation or rigid foam panel insulation. Because it’s still relatively new and mostly requires professional assistance, spray foam is expensive. If you were to have a company come out to your house to complete a project, it’s likely to cost you thousands.

Rigid foam insulation is expensive as well, but not nearly as much as spray foam. It can be easily handled by the homeowner at whatever pace he so chooses. There are no chemicals hardening in the tip of a spray gun and no mad rush throughout the project area to get things done on schedule. And rigid foam has a nice high R-Value per square inch, so it competes almost directly with spray foam. Rigid foam can also be sealed into an area, unlike regular fiberglass insulation.

When I was thinking of what I wanted to use to insulate the basement of this house, I pretty much knew I wasn’t going to use spray foam. I work far too slowly to be near anything like that. Perhaps if they offered some homeowner version that came in small cans, I’d consider it, but as for what’s available now, the containers are simply too large. I knew I’d be far better off with sheets of rigid foam insulation sitting there in the basement waiting for me to get around to doing what needed to get done.

If you read my previous post, you most likely saw the pictures I took of my truck at the building supply store. In the bed of the truck, I had two 4’x8’x2″ sheets of “Dow Styrofoam Scoreboard Insulation.”

I decided to buy the 2″ thick sheets because they have a high R-Value of 5 per inch of thickness. That’s pretty good for insulating the space between the basement and living space. For outside walls, I’m simply going to lay rigid foam over the existing fiberglass insulation, to boost and seal what’s already in place. When I’m finished, I expect a very well insulated area.

For my first project, I pretty much had my hands full. The fiberglass insulation was sagging and falling out of the joist and stud areas. There were gaps that were letting cold air creep in and to be honest, I just think it looked bad. The area was small, so I thought it was a good spot to figure out and get used to how the material worked.

The first thing I tackled was to pull all the old insulation out of the areas that couldn’t be saved and to vacuum up all nearby debris. This made my already tight and unpleasant work area much more bearable. Just imagine being stuck in a place like this, surrounded by particles of fiberglass floating through the air. Not fun.

Once I had things in the first area cleaned the way I wanted, I began measuring and cutting pieces of the rigid board to fit in between each wall stud. I fit each piece in.

And since the corner gaps were really tight, I simply added some painter’s caulk as sealant.

I did the same to the other side of the staircase.

That was all done yesterday. This morning, I began working on the area directly beneath and beside the stairs.

I cut the foam board insulation and placed it between each floor joist.

And lastly, I covered the existing fiberglass insulation on the exterior walls and sealed the larger gaps with “Great Stuff” expanding foam and the smaller one with the same painter’s caulk I used earlier. There are also two floor joists that you can’t see in these pictures. I insulated between them as well.

You may be asking yourself why I didn’t just leave things alone in this area and why I chose to use the rigid foam board. Well, from what I’ve found with fiberglass insulation is that it has a tendency to sag over time. If it absorbs any amount of moisture, it starts looking really bad and basically, if gaps are opened up in between pieces or between the insulation and lumber, it’s rendered useless. It’s almost as bad as having no insulation at all. What I wanted to “cure” in this small area was the air leakage into the basement area from outside. The rigid foam, the caulk and the expanding foam spray did the job. Now, onto the rest of the basement.