Insulating around replacement windows?

Question

What are some opinions of the best way to insulate around the replacement windows when you install them. I am currently using batt insulations and pushing it in all around the window with a putty knife, since I have tons of extra batts to use. What has anyone else had success with? Is that non-expanding foam any good? At $5 a can its quite pricey. Just curious of different or most successfull options out there.

Answer 1

When we had our windows replaced, the professional installers use batt insulation as well. The expanding foam stuff might seem to give a more complete fill, but I would expect that the time and mess (not to mention the cost as you did) would not make that attractive. I'm betting that in order to get a more complete application, you would be "over filling" the gaps and then would have to sand or saw it down in order to get the molding back in place. I'd stick to the batting and be sure not to pack it too tight. The insulating properties come from the trapped air in the insulation not from the fiberglass. So keep on trucking and good luck.

Answer 2

Depending on your climate, 1/4 inch isn't much. Many new houses have much more than that much space in construction errors. While you have the opportunity, it wouldn't hurt to insulate this area, though. Using scrap pieces of fiberglass would be a waste. You'd have to stuff it into the crack and this reduces its insulating value. The most effective was to insulate this area would be to use an aerosol product such as "Great Stuff", found at any hardware or home improvement store. It's fun to watch it work, but be careful that you don't use too much. It expands to fill a void a lot more than you may think.

Answer 3

Depending on the size of the gap around the windows, I will use foam, battens, or both.

As someone has already mentioned, the idea is to trap the air. So, you want to seal around the windows. You can do this from outside by applying a bead of caulk when the windows are installed - this also helps seal the window frame from wet weather (I always caulk in my window frames)

For very large areas, I will run a bead of foam around the inside to help seal it again, to keep wind from blowing through, and finish up the space with battens. I dont attempt to fill the whole space with just foam. This seems to me, to be the most cost effective solution, as you get the benefit of both products, with minimal cost... say one can of foam, as opposed to several, hehehe.

For very small areas, I will just use the straw on the foam can, to help seal the area -- as I normally use the foam anyway to seal the exterior side of the gap, I just go ahead and fill in any really small places.

One word of caution to those who havent thought about it.... do not use EXPANDING foam around windows, as the expansion can put them in a bind, and make the windows stick, hehehe. Instead use a product like DAP makes which expands 75% immediately... not GreatStuff, which continues to expand over time. (The DAP white foam also cleans up with water -- GreatStuff, you have to wear off, lol)

Congrats on the new windows

Answer 4

Expanding foam is best. Will insulate better and at 5 bucks a can you will make up for in energy savings. The thing is that you have to be prepaired to use the whole can because it will clog up and be no good.