[TheBigPig]

Hey guys, I've replaced many old weighted wooden windows in the past and now that I have moved into my newest house, I plan on doing the same.

These are old lathe and plaster houses, so pulling trim is not preferred, as it usually ends up with plaster work needing to be done

In the past, I would cut strips of fiberglass insulation and shove them into the hole where I removed the window pulleys. I'd use a thin piece of wood to basically stuff the insulation up into the cavity and fill it pretty tightly all the way through. I know that fiberglass insulation isn't meant to be stuffed in this way, but always figured it was better than nothing, and wanted to be sure the whole cavity was filled.

I'm now wondering if I should be drilling a set of holes down the inside of the rough opening and spraying in foam insulation. Only a few things to consider, how do I know that I have the whole cavity filled, and also, I really hate working with spray foam.

Any ideas/thoughts are appreciated. Is using spray foam that much better?

Thanks,
the pig

 

[WhatRnsdownhill]

if you make 1/4 inch holes every 6 inches and fill from the bottom up wait a few seconds for the foam to expand and come out the hole above and continue on, it might take a few times to figure out how much to squirt in, also make sure the side jams are secure so the foam doesnt push them out and cause problems with the new window going in or binding...

 

[ront02769]

Or use the specific door and window foam that does not expand forcefully. Ron

 

[Windows on Wash]

You can use phone but you'll burn through a whole bunch of it to fill that space and you may get some leakage in overexpansion in some cases.

If you get a foam gun with a long nozzle, the ideal thing to do would be to foam seal the outside edge for air leakage, then to stuff in a dense batting insulation like a Roxul.

Seal up the inside and you are done.

 

[ron45]

What are you replacing the existing windows with.?

Is it really worth worrying about.?

What are you filling the rest of the walls with.?

 

[TheBigPig]

Thanks for the responses. Maybe I'll at least give the foam a shot on the first couple windows and see how it goes.

Ron, to answer your questions:
1. Replacing the windows with Anderson replacement windows, specifically made for this application.

2. I think it's worth worrying about, I have access to empty cavities that are only separated from the outside elements by the exterior trim. I understand that the rest of the house is uninsulated, but at least I have the brick, frame, studs, and plaster providing some barrier.

3. See above, I'm not filling the rest of the walls unless they come down for some other reason.

 

[KathrynCecelia]

I live in a home that was built in 1903. I have those same windows. I also have volunteered at our Habitat. At Habitat I am on the Seal Team. We seal the homes so there are no air leaks. We use foam exclusively. Foam will continue to grow after you take your finger off the button. I think drilling holes, the exact size of the straw on the foam, at the top and bottom of the casement; foam and then drill a slightly larger hole, to probe for the fill, in the middle. If the middle was missed, use foam in your probe hole. After a few windows I'm sure you'll develop a feeling for the success of the foam to fill the space. You should wait for the foam to cure our you won't feel the difference. (At Habitat we have had a follow up with infrared and can "see" where we miss.) Perhaps arranging for an infrared camera to see what's up would help. Oh, BTW, I, too, dislike working with foam... so I now wear disposable gloves, put a drop cloth where you work (I'm sure you have finished floors and rugs, Habitat doesn't). It's better to use short blasts of foam, and let it expand a bit, but keep doing it so the first blast doesn't block successive efforts. I think I'd drill about 9" from the bottom of the cavity; push straw in as far as it will go aim the straw downward, and withdraw as you foam. Then using the same hole insert star as deep as it will go and aim upward and repeat. Then I'd do the top. If they didn't meet in the middle I'd fill the middle the same way. I hope it works. Once foamed I think you won't be able to remove the cover, because the foam will stick to it and prevent it from coming free. I think if you left the cover off (where you can replace the ropes and weights) and foamed you'd have a lot of clean up to do. You'd end up with perhaps more mess on the woodwork, and might have issues getting the cover back on when the foam is set. It will be interesting to hear how well or poorly it works.

 

[carpdad]

You will miss chunks of areas with the foam, and you can't overfill-hoping it will self fill. Walls aren't insulated and once insulated the weight space will not matter much in the whole of the insulation value. I'd stuff tight with fiberglass for draft stop. Old houses have lot of spaces between the top and bottom jambs and the framing. If you're keeping the head jamb and the saddle, insulating just the sides may not matter much.

 

[TheBigPig]

Kathryn, thanks for the reply, but I think that carpdad may have hit the nail on the head here. Maybe I should stop thinking of it as insulating and think of it more as filling the voids to reduce draft around the windows. If that's the case, I may just stick with the fiberglass, since I can easily stuff it into the voids.