Window insulating advice needed

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  #1  
Old 04-23-19, 09:24 AM
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Window insulating advice needed

Good day, all!
Hoping someone can help. I've removed the trim around my windows to better insulate against drafts. Currently, there is fiberglass insulation. I was going to leave the fiberglass but use expanding foam only directly behind the trim. Now I'm thinking I should try to remove all the fiberglass. Problem is that some gaps are very tight. In one case, drywall presses firmly against the top of the window frame. 3 questions...
1) Should I remove all the fiberglass insulation and apply 2 passes of expanding foam (once towards the exterior brick then once near the interior trim)?
2) Should I cut the drywall to make sure I have a decent gap for the expanding foam's straw to pass all around the window frame?
3) What happens if EVER the window frame needs replacing? Will it be impossible to get out?

Thank you for any responses! Much appreciated!
 
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  #2  
Old 04-23-19, 09:50 AM
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Cut the drywall back as much as you need then dig out as much fiberglass as you need to get a good seal with your foam. Anyone who wants to remove the window will just run a sawzall around the window to cut the foam... no big deal.
 
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Old 04-23-19, 09:54 AM
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Didn't think of the sawzall! Thanks for the advice. I guess I knew how I should proceed, just wanted someone to validate. The wife won't be happy but it'll be done right! Thanks, Xsleeper!

Wait, something just came to mind...
I remember very thin shims around the window frame. I'm talking 1/8". If that's the case, I'll have no choice but to keep the fiberglass insulation as the straw will never fit in there. Dang.
Will only be able to use the expanding foam closest to the trim...
 
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Old 04-23-19, 10:08 AM
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Unless you are able to get a substantial amount of foam into the space there will not be much insulating effect from the foam.
Since drafts are your concern you could press in duct seal which is a hand workable sealant or use acrylic caulking.
Make sure you use acrylic caulking because as much as some ppl like silicone based sealants it is near impossible to totally remove.
 
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Old 04-23-19, 10:58 AM
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And make sure you are using low expansion foam!
 
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Old 04-23-19, 12:38 PM
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I didn't think of acrylic calk behind the trim. I use it all around the outside edges of the trim. Thanks for the advice, GregH.
Thanks, Marq1. I made sure to get low-expanding foam!
 
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Old 04-23-19, 05:16 PM
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I'm confused. Got home and removed the trim around 2 more windows. There is little-to-no gap around the window frame. Was the window frame installed first and then the drywall/plaster later? At this point, i don't think i can do much unless i really do cut a gap all around. Where I fo see shims, they are between the window frame and drywall. I would need to cut the drywall everywhere there isn't a shim cause i assume that's how the frame is held?? I will try to attach pics...
 
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Old 04-23-19, 05:28 PM
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No gap at all. Should I make one or leave as-is??
 
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Old 04-23-19, 05:32 PM
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You haven't cut the drywall back to the edges of the studs yet, have you? The rough opening is always bigger than the window, but how much is anyone's guess until you cut the drywall / plaster back.

If the wall is plaster, the plaster is applied after the window is installed, so the plaster will go right up to the window and it covers up the rough opening.
 
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Old 04-23-19, 06:22 PM
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There you have it. Plaster is applied AFTER the window. Explains why there is zero gap in most places. No, Xsleeper. I haven't cut anything back. Wondering if i should just caulk the very thin gaps between the plaster and the frame or cut a gap around the frame perimeter to replace the fiberglass foam with expanding foam. Will the results be significantly better over the tight-gap plaster? In another window where i have a thin gap, i can actually see light from outside in a couple of tiny spots.
 
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Old 04-23-19, 07:13 PM
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It's pretty hard to seal a crack... all you can do is caulk it. It's better IMO to open it up as wide as you need so that you can inspect the window perimeter and foam it. Often you find no insulation at all. And it's better for the entire jamb to be insulated all the way to the exterior trim rather than to allow that cold air to penetrate all the way in to the caulking.

The only caveat I would add is that when you do cut the plaster away, you might be removing "some of" the support for the window. So if the window seems loose at all, you might want to shim it once you cut it back to the rough opening. But foam also does a pretty good job of fully supporting the window, once it has cured.

Depending on the type of plaster you have (some is about like cement) you might want to locate some diamond grit Sawzall blades. Have someone vacuum with a shop vac while you cut.
 
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Old 04-24-19, 12:02 PM
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XSleeper, thank you VERY much for your insight and advice! You've given me a lot to think about and have pointed me in the right direction. I dislike using the sawzall when I don't know what's behind the wall (nails, half-assed wiring). I may get a diamond disc for my angle saw or consider a dremel saw max. The first thing I need to do is discuss with the wife considering the amount of dust this will create despite best efforts. Then, I'll consider how badly I want to live and make a decision. THANK YOU, ALL!
 
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Old 04-24-19, 12:18 PM
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Just thought of it...I may buy a diamond jigsaw blade. Hmmm...
 
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Old 04-24-19, 01:22 PM
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You can also have someone spray just a small stream of water on it while you cut. Drill a tiny hole in the cap of a water bottle. Keeps the dust down.
 
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Old 04-24-19, 03:14 PM
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One other thought. If the cavities are empty... and you just want to fill them, you could use a hammer drill and 5/16" masonry bit to drill holes every 3" or so around the window perimeter. Then you could inject the foam through the hole.

Only danger with that is overfilling or underfilling the cavity since you won't be able to clearly see what you're doing.
 
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Old 04-24-19, 04:28 PM
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Hi! Yes, I was actually thinking of drilling every 5" and angling the drill bit side-to-side to spray. As you said, I won't be able to tell what I'm doing. To be honest, I'm the type to tear things down and do it right no matter what but just thinking of the dust hassle...I may opt to just seal amy gaps and forego opening the edges. Knowing me, I'll change my mind Saturday. :P
 
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Old 04-29-19, 04:55 AM
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OK, so after weighing my options on cutting the cement stucco, I opted to buy a Dremel Ultra Saw kit because one of the kits includes a vacuum attachment and a diamond disc. I assumed this would make a lot less dust than my angle grinder, but there was still a LOT of dust created. I taped a plastic drape from ceiling to floor. In some areas, I could see light through the window frames, telling me there wasn't enough insulation and the exterior caulking had cracked.

The Dremel was phenomenal and the depth adjustment and vacuum attachment greatly helped. I then removed the pink fiberglass insulation and sprayed expanding foam (for windows) as deep as I could. Trimmed the foam once dry and installed new trim. This will look great once I fill the nail holes, caulk the joints, and roll a coat of paint. Two windows down, 4 to go. Thanks for the advice!

 
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