Insulation around windows ?

[Cycledude]

Installed all 12 new windows in my 86 years old house. The outside work is mostly done but now I need to finish the inside work, need to insulate the small space around the windows and am wondering about using that spray foam type insulation that comes in aerosol cans , have you ever used the stuff and if you did how do you like it ? Maybe I’d be better off just using regular fiberglass insulation ? Thanks for your help.

 

[duffer]

IMO, fiberglass won't work near as well as the spray foam. The foam expands into minute areas that you can't get fiberglass into without crushing it, which defeats the purpose of the insulation in the first place.

If you use the spray foam, BE SURE to get the low expansion formula made specifically for doors and windows. The regular foam can expand too much and put pressure on your jams and glass potentially.

 

[Doofy]

Use the spray foam that is made for doors and windows. It fills the gaps extremely well and stays pliable and does not expand enough to swell or warp anything. Great stuff!

 

[EddieWalker]

First, make sure it's the foam designed for windows. The other stuff will expand so forcefully that it will bow your windows.

In my opinion, using window foam should be required. Taping the exterior is probably more important, but foam is also very important.

Your biggest enemy is allowing air to get around the windows. If air can get through there, then the heat or cold from outside will get through there too!!!!

 

[Have tractor did travel]

Some of that foam is labeled "sealant" which is what I think of it as being. Other of that foam is labeled "insulating sealant". No R value is given. To me - no specific claim, probably means not much R value. I've been insulating the outside walls of my 102 year old house. Around the windows, where I could push in insulation, I pushed in insulation. Where it seemed nonsensical, I sprayed foam. Spray lightly - it expands, as you don't want the foam pushing the window frames out of plumb. You can always come back later and give it another shot.
After researching the R value of new windows, and storm windows, I decided to keep the original windows (and the money) and just re-glaze, insulate, and caulk. It's worked out well. No drafts. We added interior shutters for its additional insulating value (stagnant air between shutters and windows).
Incidentally, if you are using, say R15 fiberglass, and pack it into the opening, you do not increase R value. You don't lose R value, but there is nothing gained by compressing the insulation.

 

[Diggin It]

If you go with foam, use the stuff marked windows and doors or small gaps and cracks. The regular stuff can expand too much and warp the sides which can cause problems for the windows.

 

[ROUSTABOUT]

I install replacement windows. I still pack insulation around them. After one dose of a bunch of cans that wouldn't spray, I learned a roll of insulation works every time.

 

[AndyMA]

I install replacement windows. I still pack insulation around them. After one dose of a bunch of cans that wouldn't spray, I learned a roll of insulation works every time.

The problem is that doesn't meet the IECC Energy Code which requires foam. Keep n mind that fiberglass insulation has no air sealing properties As others have stated use low expansion window foam, I do energy audits and see windows you can't open with normal foam

 

[ROUSTABOUT]

The problem is that doesn't meet the IECC Energy Code which requires foam. Keep n mind that fiberglass insulation has no air sealing properties As others have stated use low expansion window foam, I do energy audits and see windows you can't open with normal foam

National Fenestration Ratings Council. Does his 86 year old house even have wall insulation? As far as air infiltration, I caulk each side and all the wood completely. I've also built several ICF homes. But, people just can't see it, and want those 2x4's. ICF is phenomenally better.

 

[Cycledude]

National Fenestration Ratings Council. Does his 86 year old house even have wall insulation? As far as air infiltration, I caulk each side and all the wood completely. I've also built several ICF homes. But, people just can't see it, and want those 2x4's. ICF is phenomenally better.

No this house did not originally have insulation inside the walls but about 30 years ago I blew insulation into the walls and ceiling, obviously that doesn’t work very well but it’s better than nothing.

 

[MossRoad]

Don't pack insulation around windows. It should be put in so that it's not compressed. If you pack it, the insulation value will be greatly reduced.

 

[ROUSTABOUT]

No this house did not originally have insulation inside the walls but about 30 years ago I blew insulation into the walls and ceiling, obviously that doesn’t work very well but it’s better than nothing.

Always a pain with fire blocks.

 

[jaxs]

Since you say outside work is finished it's probably too late on this job but wrap windows on next job before installing siding and trim. That not only seals out air but prevents water soaking into foam then rotting surrounding wood.
Oh BTW USE FOAM SPECED FOR WINDOWS AND DOORS.

 

[timbatrader]

I have recently put windows into a new build I push a PEF foam rod into the back of the gap as a back stop before putting the foam in I found the cans don't work on cold days so wait until midday on a sunny day if in winter another tip is that what sets off the foaming reaction is contact with the moisture in the air or suroundings so spray water around the windows before foaming which makes the foam expand more predictably therefore easier to avoid over foaming with it expanding where you don't want it

 

[Have tractor did travel]

Don't pack insulation around windows. It should be put in so that it's not compressed. If you pack it, the insulation value will be greatly reduced.

From R-value (insulation) - Wikipedia
"Squashing two layers of batting into the thickness intended for one layer will increase but not double the R-value. (In other words, compressing a fiberglass batt decreases the R-value of the batt but increases the R-value per inch.)"
In other words, packing in insulation, as I suggested, has diminishing returns, but more R value is still obtained. Since insulation is cheap, and you're only doing around windows (not using much), I still recommend you seal where you can, and pack where you can, and the two are not mutually exclusive.

 

[oosik]

I built my PanAbode cedar timber home here in 1982. Used spray can foam around the two exterior doors and all the windows. The house is still sealed up - tight as a drum.

 

[IH2424]

Installed all 12 new windows in my 86 years old house. The outside work is mostly done but now I need to finish the inside work, need to insulate the small space around the windows and am wondering about using that spray foam type insulation that comes in aerosol cans , have you ever used the stuff and if you did how do you like it ? Maybe I’d be better off just using regular fiberglass insulation ? Thanks for your help.

Another vote for the Window and Door version of Great Stuff spray foam. I have replaced almost all the windows in our 100 year old farm house over the past 20 years and used it on every one. I did make the mistake of starting with the wrong foam and did spring one of the casings - i had to take the trim off and cut out the foam, then put in the right stuff. I use a hand miter saw to simply saw off any of the foam that sticks out of past the edge of the window.

 

[lpakiz]

We removed every 12" board and 3" batton of vertical Red Cedar siding to replace all windows and add 1/2" of "DowBoard" insulation. We replaced the boards exactly where they came off of, and I used that canned foam to stop insects and vermin from using the 3/4" voids between boards as a highway. I put a dab at the top, a dab in the middle and a dab at the bottom.
I found that a hot, wide putty knife and a propane torch to heat it would cut the excess foam perfectly. Like a hot knife thru warm butter, you could say.

 

[Buzzard7]

Use spray foam for best insulating value.

 

[dh206]

If you're going to use the window foam (which I highly recommend), and you have 12 windows, it's worth it to spend the extra $20 for the applicator. It will make your job easier and faster and more accurate. There's a "professional" spray foam gun that is reusable. The cans are bigger, so you get more out of a can for about the same price as the consumer can. You can get them at Lowes, HD, or Amazon. Get the spray foam cleaner too and rinse out the gun according to the instructions as SOON AS YOU ARE DONE FOR THE DAY. Don't wait or you'll make the gun a pretty stainless prop that is effectively sealed shut.
And, as somebody else said, the MOST IMPORTANT thing when doing windows is to get the taping/flashing done around the windows right! If you don't do this, you'll have water in the walls, and rot, and then your sheating and insulation and windows and framing all need to be replaced the hard way. Trust me on this, you don't want this. I had to have all my windows replaced and some of the framing around them as a result of this from a professional window installer not properly doing the flashing. It's a very, very important thing.