There are many different opinions on the proper insulation technique. One school of thought says that you should install a vapor barrier (a plastic sheet) on the outer side of the wall, and then mount your fiberglass insulation, and then your walls. A vapor barrier is essential to keep moisture from forming in the wine cellar or behind the walls.

We decided to use a different approach: spray foam insulation. The insulation is applied as a liquid, and expands as a foam, and then hardens as a “solid”. Our contractor blew the the foam into place, smoothed it out, and let it harden.

This approach has a number of advantages.

First, it’s relatively quick. The entire job can be done easily in half a day. If you were to install a plastic vapor barrier, then cut and install fiberglass insulation, and fasten it into place, the job would take much longer. You may be able to simply push the fiberglass into place in the walls, but gravity won’t allow you to do that in the ceiling; fastening is necessary. With spray foam, it’s quick and it’s done. Here’s how it looks in the ceiling.

Second, since the foam dries hard, there is no need for a separate vapor barrier. Fiberglass insulation will retain water if it gets wet, so a vapor barrier is essential. With “solid” insulation, water cannot penetrate, so a separate vapor barrier is not necessary.

Finally, as you can see with the ceiling picture, foam is great for filling in every “nook and cranny” in a ceiling or wall with wires, pipes and other impediments. Fiberglass insulation will not fit as tightly.

Therefore, my vote is for spray foam insulation.

Framing is not necessary, since the floor joists that hold up the upper floor will serve as the area to attach the drywall, and to put the insulation.

As you can see from this picture, our house has various electrical wires, gas lines and plumbing running through the joists. It is necessary to review what’s there, and determine if anything needs to be moved before you proceed. In our case it was possible to frame around everything, so no major moving was necessary.

One final question to ask yourself: Will I ever need to access this area, or run additional wires? In the picture you can see four grey cables taped in a bundle; those are the cables from our television satellite dish. Once the ceiling is constructed, they will be inaccessible. If you think you will ever need to run wires through the ceiling in the future, you could consider running a conduit through the ceiling before you close it.

A conduit is simply empty plastic pipe, open at both ends, so that you can easily run wires through it. I suggest running rope from one end of the conduit to the other, so that you can pull your wires through it in the future. In our case it wasn’t necessary.