The front of my house is brick, and has vinyl windows. I noticed the
other day that the caulk around the windows has deteriorated. Upon
removing the caulk, I noticed that there is a largeish space between
the window and the brick, that is only about 1/4" where the two meet at
the window frame, but behind there is a greater void - too large to
fill with backer rod.
Should I insulate this space before I replace the caulk? If so, with
what? I am leery to use expanding foam because of the mess, and most
window manufactuers don't recommend it.
I would be tempted to use some of the very low expansion foam made for
windows and doors. I have used fiberglass but find that when packing it in
it can be too tight or not enough, worse yet, I have found that condensation
can wick through joints in the window and soak into the fiberglass
insulation as if it were a sponge, where it sits forever rotting the window
frame and the house framing. Just use it gently, and insert as far back as
you can, extend the tube if you have to, don't over load the space with the
foam, add more to any voids once it is hardened.
There are low-expanding foams that are made for windows and doors:
This is a low-expanding latex foam. Flexible when dry, water cleanup,
$3-$4 a can. I've used it on many windows with excellent results and no
There's also a "Great Stuff" low-expanding foam. It's a polyurethane,
so if any of it goes in the wrong place, you need acetone to clean it
up. Also costs more than the DAP stuff.
The latex foam is made by Dap, and with recent price increases, it's now
$6-$7 a can. Don't use the polyurethane foams (Great Stuff, etc.) on
windows because 1) they expand too much, and 2) they are a royal pain to
What I do in situations like that is; take regular bat type insulation,
cut it into strips and jam it in with a putty knife, leaving enough
room for the caulk to seal it up. I get a little itchy, but nothing a
shower won't fix, my method is simple, cheap and effective.
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