Spraying foam around the windows

2013-11-05 by . 14 comments

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One of the best home improvements I’ve made in a while, is one you’ll likely never see (unless you read this blog). And at about $10.00, it was also one of the cheapest projects I’ve done.

When the temperatures started to drop, I noticed that the second floor of my house was quite a bit colder than the first. So, I did what my mother had always done. I went out and bought window wrap, and applied it to all the windows in the house.  You know the stuff. The plastic wrap, that shrinks with a hair dryer.

Yeah, that stuff.

After spending a day installing the stuff, I noticed it was still quite cold upstairs.  As I investigated further, I found that I could still feel a draft near the windows.  So I thought to my self “The air must be coming in around the window, not through it.”.

The next day I removed the casing from one of the windows, and found a puny bit of fiberglass batt insulation stuffed in around the window.  I couldn’t believe that in a newer home, in the northern United States, this was the way they insulated around a window.  I knew what had to be done, so I hopped in my truck and headed to Home Depot. Where I picked up two cans of Great Stuff™ Window & Door, for about $10.00.

If you’re going to do this, make sure you get the stuff designed for windows and door.  The “regular” Great Stuff Gaps & Cracks may expand too much and/or too quickly, causing the window or door frame to bow out.  If this happens, the door or window may not function properly.  The window & door formula is created to expand with less force, so it will not bend the frame of a door or window.

Installing the stuff is dead easy.  Once you have the window trim removed, and the gap around the window frame revealed. You simply gently pull the trigger, and fill the gap about 50% of the way (that’s 50% of the depth, you want to fill the entire width). Run a smooth continuous bead in all the gaps, and sit back an watch it expand.



Don’t worry about being super neat, you can trim off anything that expands out of the crack later.  Use a hack saw blade, or utility knife to trim off any excess, once the foam has cured (usually about 8 hours).


Once the foam has cured, and you’ve trimmed off any overflow. There’s nothing more to do except, install the casing, and celebrate a job well done.

I found that one 16 oz. can, was enough to do two standard sized windows. You’ll also want to be aware that once you start using a can, you have to use  the whole can.  If you don’t use all the product in the can, you cannot save the remainder for later. So before you start spraying, make sure the trim is removed from all the windows you plan to insulate.


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  • Bryce says:

    The great stuff “gun” eliminates the need to use the can in a single setting.

    • tester101 says:

      The Great Stuff gun might make sense if you’re working with this stuff often. If you’re only using it once or twice, it’s difficult to justify a ~$30 tool to save a ~$5 can of product.

  • Isn’t that material inflammable?

    • tester101 says:

      According to Dow’s literature, “Cured foam is combustible and will burn if exposed to temperatures above 240°F (116°C).”. However, the propellant used to move the foam from the can is inflammable. All ignition sources should be extinguished while actively spraying Great Stuff, and should not be reignited until all fumes have cleared.

  • Melinda says:

    Me and my husband used the same foam material at home when renovating. At first side looked really horrible, but really helped. Turn out it is really amazing product: fills 100% of the gaps and you enjoy the warmth of your home like never before.

  • Joana says:

    That is cheap and effective way to insulate the windows. The best thing is that you can do it by yourself and you safe a lot of time and money.

  • Chelsea says:

    Hi, I just recently started removing my window trim to insulate around the windows. The plaster around the windows in some places is cracked and very drafty and in other places is snug up to the window frame. Should I only fill in the places that need to be filled with insulation or should I remove the plaster to make a gap and spray foam around the entire window?

  • Annie Craven says:

    Amazing how this stuff works and super handy! Thanks for sharing your experience.

  • pat says:

    how do you remove the stuff in spring/summer when you open the windows for aeration… thanks

    • Mike says:

      You spray it between the casing and the rough framing. Not the window area itself.

  • Michael says:

    Spray foam is getting more and more popular in the UK, it’s a great way to insulate around the windows and protect for years to come.

    Many listed buildings are using spray foam loft insulation, and more and more in commercial use.

  • Brigitte says:

    Hi, I just had a front door installed and this product was used as insulation. I’m painting the trim pieces and want to know how to apply paint over the foam after it cures. The paint seems to just “slide” off”

  • David Herzfeld says:

    The Blue can expanded way to much and bowed our window so that it will not close properly. There was no sheet rock on the inside so there was plenty of room for the foam to expand. Looks like I will have to dig a lot of it out so it can close.

  • This is great….I have some drafty windows that need some maintenance and this is just what I need to try.

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