Window insulation?

Old 11-12-17, 10:55 AM
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Window insulation?

Hi! I was curious how much of a difference insulation around a window makes? I took the trim off,on a sneaking suspicion I had, and found only the tiniest bit (sporadically too) of pink insulation in there. Before ripping it all off and spending money on the foam and time I was curious if thats what could be causing cold floors and areas surrounding all of my windows? Thanks so much you guys are awesome!

Ps: if so, how big of a difference will it make? Im assuming both of my doors are the same way as well, but my wife isnít convinced and thinks im wasting money.
Old 11-12-17, 11:26 AM
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Windows are cold in the winter because they are 90% glass, and glass is a poor insulator. When it's 0F outside and 70F inside, even the best IGU will be around 47-52F center of glass, even less on the glass perimeters. Since cold air sinks, that's one reason why it's cold on the floor in front of a window. Also why they usually locate floor registers in front of windows... for heat... to keep the windows from icing up in the coldest parts of the year.

Air infiltration is another matter. If you have an uncaulked, uninsulated window letting a cold draft in, you would definitely know it on a cold windy January day. And fiberglass doesn't stop air, it only slows it. Expanding foam does both... air sealing and insulating. At $3 a can, it's not like you are wasting a lot of money.

Whether or not your lack of insulation is letting a lot of cold air in is anyone's guess. Testing your windows on a cold windy day with a smoking incense stick would tell the tale. It will indicate where the draftiness is coming from. Foam insulation can help with that by completely sealing the outer perimeter of the jamb. But it won't help much if the sashes (the part that slides up and down or opens) are also drafty. And it's probably not magically going to make a night and day difference in the temperature of the floor or room... but it would likely help.

That being said, stuffing fiberglass around window jambs was the usual way of insulating them ever since fiberglass was invented. So there are millions of windows insulated just like yours. And more fiberglass is not necessarily better. Loose insulation insulates better than tightly packed insulation. It has to do with slowing air movement... not cramming as much fiberglass in as possible.
Old 11-12-17, 12:50 PM
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If you do use some can foam, 2 cautions. Around windows and doors they sell a low expansion foam so it won't expand and push the frame over. And, can foam doesn't fully expand in cold temperatures. So, difficult time of year to be using foam insulation. Still a temperature limitation but I have used the "DAP" zero expansion and they are correct, once it exits it initially foams up and that is it, done. I have used the popular brand ow window and door and the next day it was all over the floor. I tried using a lot less but it was hit or miss to get a good fill.

X is correct, it won't be earth shaking but should improve your issue.

Have you considered the shrink wrap plastic film?


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