There were several things we had to take care of before the real winter hits here in Chicago. Our energy audit produced bad results (which weren't so surprising), and so we decided to take matters into our own hands. We installed electrical outlet sealers, and then started the more labor intensive (but not difficult) task of placing insulating foam sealant under our quarter rounds and in some holes in the attic floor...
This stuff expands a lot, so the trick is to spray a little and keep it moving along any given edge/space. After it dries (we gave it a good 3-4 hours), you can then go along the edges with a utility knife and scrape until even with your wall, floor, etc.
Here's a comprehensive list of where to use foam sealant, including:
- Under baseboards
- Window and door frames
- Electrical outlets
- Pipe/wire penetrations
- Conduit penetrations
- Air/heating vents
A can of Great Stuff runs anywhere from $2.99 (we've seen it on sale) to $5.50. Make sure you have a spray plan before starting; once you open a can you need to use the whole thing.