Thursday, December 5, 2013

How to insulate a threshold

Winterizing! It never ends. At least this is something I won't have to undo in three or four months.

One of the coldest spots in the house is the area by the back door. I know the back door needs a new door sweep, but today I'm going to try and block some air by insulating the threshold. For this project you'll need:

  • gloves and eye protection
  • screwdriver
  • putty knife or painter's tool
  • utility knife or scissors
  • foam weatherstripping or rope caulk
  • small piece of fiberglass insulation
  • caulk and caulk gun

Here's our before. This was caulked, but you can see that there's a gap between the tile and threshold now. Not only is it ugly, it's drafty. Sorry for the blurriness, I didn't catch that when I took the picture.

Start off by removing your threshold.

Pry it out with your putty knife or painter's tool, then scrape any old caulk off of it. Be sure not to lose your screws.

Pray for no water damage. And...yay! There are a few dark spots, but they're solid and not splintery or spongey, so I'm calling it good.

See that huge gap between the subfloor and the wood threshold? That's not doing our heating bill any favors. Cut a strip of your foam insulation or rope caulk and gently press it in place. You don't want to squish it too much; the more insulation is compacted, the less it works.

Mine doesn't go all the way over because the next piece of subfloor actually does go all the way to the threshold. There was a very small gap, so I could have cut a piece in half lengthwise, but I figured the next step would take care of any remaining gaps.

Now it's time for the fiberglass. A whole strip of fiberglass insulation won't fit under the threshold, and even if it did it'd be too flattened to do anything. I peeled one layer of insulation, maybe 1/4" thick, off of the main piece. Then I laid it across the wood threshold.

If you think that water could get under here, you should wrap your insulation loosely in plastic. Not too tight; we don't want to compact it. Just enough to keep any moisture out.

Lay the metal threshold back in place to test your fit.

My insulation was slightly too wide, so I trimmed about 1/2" off one side. Once it's all fitted correctly, screw the threshold back in place. After you clean off the dirt that was under your threshold, of course.

Much better, but there's still a small gap.

For that, we need caulk. Sweep up all the random debris that came out from under the metal threshold first. I use Dap Dynaflex 230 in clear. Actually, I would use white here, but I had clear. This is before I went over it again to clean up a bit more of the excess.

Much better.

1 comment:

  1. This is such a good idea! Thanks for sharing! I live in a drafty old house, and I really need to do this kind of insulating around my house. The rolled up towel thing in front of the doors is getting old! :)