I have been sitting on my salvaged insulation for quite a while, but have finally come to the point where I get to use it.

The aggregate base is installed, which allows me to move the 2 inch thick XPS sheets into the basement. I picked the northwest corner as a starting point.

Because none of the foundation walls are really square at the corners, but the XPS sheets are, I began laying down an oversized L-shape and adjusted the directions until the insulation sheets were as square as it could be in my old, crooked but beloved basement.

(See, the German in me is showing through again…)

While I am on the subject, I spent some time cutting the insulation sheet edges to match the subtly changing directions of the foundation wall.

Although I got the salvaged XPS sheets for cheap, I had to put some time in to check that they were square. Some edges were cut at a slight angle for the previous job, some edges had dents, or some corners had broken off.

Regardless what the imperfection was, I bought a big drywall square, scored the boards that needed attention, and cut the square back into them with a simple hand saw. The cutting with the handsaw worked really well.

The spread footings! Let’s not forget about the spread footings. I have to cut an 18 by 18 inch square out of the insulation at the spread footing location. That square will receive the spread footing pedestal.

These two inch XPS sheets are only the first layer in the insulation assembly. But they give me an insulation value of R-10 already. We could physically feel that.

Whereas previously the thermal mass of the soil and stone in the basement floor has kept the temperature down, that cooling power is now blocked and we could feel it warming up.