Can I put foam sealant in between the trim and the siding?

Jeff Haeder
by Jeff Haeder
I'm not sure if the window is sealed with caulk behind the trim. Can I put a small bit of foam sealant behind just to be safe. Or is there any anything else that I could put? I just want to make these windows as energy efficient as possible. They are floor to ceiling windows and face the west.
  6 answers
  • Susan Bechamp Susan Bechamp on Jun 22, 2015
    I would not use foam sealant of the expanding variety, such as Great Stuff. You can easily overfill those gaps and end up with foam oozing out. Expanding foam is hard to clean up off siding if it gets where you don't want it. I would suggest a silicone caulking . \It will seal up the space between the trim and siding so moisture doesn't get behind it, If you can't get the color to match, go for clear or paintable caulking
  • Luis Carlos Becker Luis Carlos Becker on Jun 27, 2015
    In may house ( Brazil) I use foam sealant. It Works . weary well . For clean you need wait the foam dry, them use a knife
  • Rockbiter Rockbiter on Jun 29, 2015
    I had a gap bad on the foundation of my house, I researched the crud out of how to seal the gap (horizontal ) of the bottom siding where it met with the foundation. That is the only type place I would recommend the great stuff, because my gap was allowing bugs inside and I used it as a sort of backer rod for the final layer of caulk. While that stuff is awesome, it is amazingly quickly messy. I would only use a polyurethane silicone caulk, you can get a color that matches primarily. and I don't think your gaps (as it appears in the photo) are major so great stuff would only ruin the nice look of your house. I also had to caulk under a drip cap of my window as a ghetto rig, but again if the pass is small just do caulk, bugs will eat through great stuff and I wouldn't recommend using it without caulking after it for a great seal. working from the inside is where you would get better results (I can take pictures of my window and show you how I insulated an already installed one as a repair if you would like, what type of siding is it is important as well to this fix. Cement siding like mine you fix small cracks with caulk. Take a picture from the bottom of the window if you could, that is a definite spot I can see , and you can as well, whether they sealed it at all in the important spots.Sorry for the long explanation but I find the more you know the better the project will go
  • Bananas! Bananas! on Jun 30, 2015
    From all the houses we've owned, I'm looking and wondering 'why' do you want to fill those? I think they're meant to look like that, it is the 'look' of that style of house. The insulation will have been put under the window frame and that piece we see is decorative only, to cover where the window meets the wall
  • Wanda sinnema Wanda sinnema on Jul 03, 2015
    I am surprised that wasn't done when they installed the window.. I'd use silicone caulk, its waterproof, which is what you want, to keep moisture from getting under the wood. I'd get some you can paint, lots of colors now, but may not get an exact match,, go close and touch up if needed, or if you change colors on the trim later..
  • Charles Prock Charles Prock on Jul 04, 2015
    You do not need to seal in the little cracks behind the window trim....When the window was installed it was sealed to the sheathing with a special tape or caulk....If you seal in the cracks you have no idea how bad that looks....We build 60 houses a year the way I'm telling you and there are no air infiltration problems whatsoever.