# Window Weight Cavity



## HomeSealed (Jan 3, 2008)

The easiest (and still effective) way would be to fill the cavities with loose fiberglass. Since you'll have them exposed, a layer of spray foam is a good idea, then fill the remaining gap with fiberglass. Sealing those up will no doubt be a benefit for energy efficiency, and may help with the sound as well. The quality and installation of those vinyl replacements may have more to do with the sound though.
The original installers probably did nothing wrong _contracturally_ by not filling those voids, although it is an extra cost that I highly recommend.


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## Windows on Wash (Aug 30, 2011)

HomeSealed said:


> The easiest (and still effective) way would be to fill the cavities with loose fiberglass. Since you'll have them exposed, a layer of spray foam is a good idea, then fill the remaining gap with fiberglass. Sealing those up will no doubt be a benefit for energy efficiency, and may help with the sound as well. The quality and installation of those vinyl replacements may have more to do with the sound though.
> The original installers probably did nothing wrong _contracturally_ by not filling those voids, although it is an extra cost that I highly recommend.


+1 on all accounts. Good post.

We do fill those voids but at an added cost. We foam them back but foam isn't cheap so it is detailed out to the customer about what we are doing.

Spray them and fill them. 

You will be good to go after that.


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## wewantutopia (Feb 28, 2012)

mferguson0414 said:


> My plan of attack for this cavity and another one like it is to put two different layers of 2" foam with a 1.5" gap between them. The first one tight to the exterior and the second one flush to the interior portion of the window frame. A question I have is do you think I should use great stuff window foam to seal up the exterior edges before I push in my 2" foam or should I caulk it somehow? My dad thinks that caulk will probably not stick to the old wood and that it may just fall. I was thinking of just applying caulk to the edges of my foam board before installing and allow it to smear as I push it in and seal it up that way. In theory this process should get me to a R20 if I buy the right 2" foam board, but I just want to make sure I seal up any air leaks and not mess up the function of the windows with the wrong foam or sealant.


This is what I did between my windows just like yours (in fact I've done my whole house like this between the studs instead of fiberglass). Just remember to leave a 1/4 - 1/2" gap on all sides of the rigid foam to allow room for the spray foam. 

You could go with 1 1/2 inch foam and add 3 pieces in there (I'm sure you'll have a ton left after you cut 2 strips. The whole board will be cheaper then too).

Also, if you go this route get the WINDOW AND DOOR spray foam so the pressure of the regular expanding foam doesn't bow the windows!!!

The Great Stuff window and door foam is in the blue can.

After you foam it in allow it to dry. Then you can cut off the foam that has protruded past the wall with a retractable break away knife (the easiest I've found) so it is flush to reinstall the trim.


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## mferguson0414 (Jan 6, 2009)

Does anyone have any idea what type of cavity is on the sides of a single window? If this cavity is 3.75" wide, will the other ones be about 2" wide and just as deep(5.5").

Also, what material are those window weights made of? Is it a material that can be recycled for $$.


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## wewantutopia (Feb 28, 2012)

It is quite possible just a normal stud bay.


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## mferguson0414 (Jan 6, 2009)

Should I do a google search for the size of a "normal stud bay"? I was thinking it would have some large cavity that needs filled because of the rope weight that would be on either side of the window. Sorry for my lack of knowledge.


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## HomeSealed (Jan 3, 2008)

It is not a normal stud bay. It is an enclosed pocket for the weights, and should be similar in size to the one in the center. mferguson, you are not the one with a lack of knowledge on this thread, kudos to you for asking questions instead of posting bad info as others do from time to time. Secondly, I would not be concerned with over expansion of the foam. The 3/4 thick (or more) wood frame will be more than adequate to protect the window from bowing considering that you are merely spraying a layer of it to create an air-seal, rather than filling the cavity up solid.
The foam/fiberglass combination is going to be easier, cheaper, and equally as effective as cutting up a bunch of rigid board.


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## wewantutopia (Feb 28, 2012)

Sorry. I just meant that you may open it up and find nothing other than the usual ~14.5" space between 16" on center studs and no weights. 

I don't really know what's back there. 

Are you sure the weight/string/pulley system wasn't in the frames that the installers removed?


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## mferguson0414 (Jan 6, 2009)

wewantutopia said:


> Sorry. I just meant that you may open it up and find nothing other than the usual ~14.5" space between 16" on center studs and no weights.
> 
> I don't really know what's back there.
> 
> Are you sure the weight/string/pulley system wasn't in the frames that the installers removed?


I don't know that I'm following you when you asked the question about the weights in the frames. Last night when I pulled off that trim the weights were laying in the bottom of that pocket with the ropes cut off cleanly.


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## Tom Struble (Dec 29, 2008)

don't forget under the sill and at the head


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## mferguson0414 (Jan 6, 2009)

HomeSealed said:


> It is not a normal stud bay. It is an enclosed pocket for the weights, and should be similar in size to the one in the center. mferguson, you are not the one with a lack of knowledge on this thread, kudos to you for asking questions instead of posting bad info as others do from time to time. Secondly, I would not be concerned with over expansion of the foam. The 3/4 thick (or more) wood frame will be more than adequate to protect the window from bowing considering that you are merely spraying a layer of it to create an air-seal, rather than filling the cavity up solid.
> The foam/fiberglass combination is going to be easier, cheaper, and equally as effective as cutting up a bunch of rigid board.


I will have to take the fiberglass into consideration when I am out shopping this weekend for what to do with the first window that I am tearing into.

I too thought that the Great Stuff window and door would be just fine for this application. Do you know if there is any way to use a can of that spray partially and then clean it somehow to use later? I don't necessarily want to use a whole can of that per window.


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## mferguson0414 (Jan 6, 2009)

Tom Struble said:


> don't forget under the sill and at the head


Good point with the sill. The header seems to have a 1.5" gap to the header board that I plan on filling with the great stuff window foam and roxall because of the tight area.

Do you have any suggestions on getting to the sill?


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## Tom Struble (Dec 29, 2008)

maybe an apron you can remove?


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## HomeSealed (Jan 3, 2008)

wewantutopia said:


> Sorry. I just meant that you may open it up and find nothing other than the usual ~14.5" space between 16" on center studs and no weights.
> 
> I don't really know what's back there.
> 
> Are you sure the weight/string/pulley system wasn't in the frames that the installers removed?


The weights would not have been removed during window installation.
Please don't take this the wrong way, but it is probably better not to comment on topics if you really don't know. I have done plenty of electrical and plumbing work in my life, but you won't see me posting over in those forums because the last thing that I want to do is give someone inaccurate information or just "guess"... Just something to keep in mind.

mferguson, you'll want to take the trim off all four sides and address all gaps and cavities. The weight pockets will likely be larger, where the head and sill will be smaller and you can likely fill them with foam alone. On the great stuff cans, you can generally use them a few times within a short period, but I don't know anyway of extending a partially used can for longer than that. Someone else may have an idea, as we use the professional gun with a screw on can for exactly that reason.


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## wewantutopia (Feb 28, 2012)

HomeSealed said:


> The weights would not have been removed during window installation.
> Please don't take this the wrong way, but it is probably better not to comment on topics if you really don't know. I have done plenty of electrical and plumbing work in my life, but you won't see me posting over in those forums because the last thing that I want to do is give someone inaccurate information or just "guess"... Just something to keep in mind.


Point taken. I should have left the window weight bit alone which is more of a window question. 

Insulation, on the other hand is one of my obsessions and I stand by my first bit.



> Do you know if there is any way to use a can of that spray partially and then clean it somehow to use later? I don't necessarily want to use a whole can of that per window.


I usually stuff a nail down the end of the tube then let it rest on something as it dries so the last bit of pressure doesn't pop out the nail. When I come to use it again I pull out the nail, unscrew the tube and clean it out along with the nozzle the top of the can (using a wire) and they're usually good to go.


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## mferguson0414 (Jan 6, 2009)

Where can I buy a pro gun at? I know Menard's sells the pro cans, just not the gun to spray it with.


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## Windows on Wash (Aug 30, 2011)

mferguson0414 said:


> Where can I buy a pro gun at? I know Menard's sells the pro cans, just not the gun to spray it with.


Online or I have seen them at the big box stores. If not there, i.e. local, try a building supply house that sells to contractors.


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## wewantutopia (Feb 28, 2012)

mferguson0414 said:


> Where can I buy a pro gun at? I know Menard's sells the pro cans, just not the gun to spray it with.



Menards rules!

http://menards.com/main/paint/caulk...-pro-13-foam-sealant-gun/p-1669331-c-7937.htm

http://menards.com/main/paint/caulk...-gun-14-foam-sealant-gun/p-1473359-c-7937.htm


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## mferguson0414 (Jan 6, 2009)

wewantutopia said:


> Menards rules!
> 
> http://menards.com/main/paint/caulk...-pro-13-foam-sealant-gun/p-1669331-c-7937.htm
> 
> http://menards.com/main/paint/caulk...-gun-14-foam-sealant-gun/p-1473359-c-7937.htm


I wonder where that gun is in my store. I really appreciate the links.


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## wewantutopia (Feb 28, 2012)

No problem... although, I was just looking at them again, it is special order only at my store and the stores around me too. Might be the same in your area too. Could always give 'em a call and see how long to order one if it is the case.


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## Tom Struble (Dec 29, 2008)

a siding supply house will have them


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## HomeSealed (Jan 3, 2008)

As Tom and WoW mentioned, a local building supply house like Allied, Alside, ABC, Norandex, Richards, etc will have them in stock. It would be a good investment for any homeowner.


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## bbo (Feb 28, 2010)

menards does sell the guns as well. the dow corning stuff some in a kit with the 2 cannisters along with a gun and various tips. I thought I was ging to go through the tips left and right. I ended up using one tip for each set I bought. I've got a bunch of tips lying around here somewhere. If you prep all the windws ahead of time and have a plan for lugging the cylinders around window to window ( there is a carrying handle ) you can probably use one tip per cannister set. The stuff is not cheap though, if you are going to do a window at a time, I'd just use the cans. closed cell is what you want for a moisture barrier.

Froth-Pak is what I used from Menards.


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## HomeSealed (Jan 3, 2008)

A froth pack at $400+ per application is way too much material for this application. Pick up a pro gun (maybe $50) and a few cans @ around $12 ea and that will do the trick.


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## HomeSealed (Jan 3, 2008)

+1 though on closed cell.:thumbsup:


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## Gary in WA (Mar 11, 2009)

Adding fiberglass alone is almost useless, right down the bottom of the list here:http://books.google.com/books?id=a2...CBMQ6AEwAA#v=onepage&q=Proskiw (1995)&f=false

The weight cavities are usually included in part of the window unit: http://chestofbooks.com/architecture/Building-Trades-Pocketbook/Windows.html
There will almost always be a rough opening framed in a wall for a window with just studs, if not studs and jack studs. 

Gary


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## Tom Struble (Dec 29, 2008)

well if the rest of the house is fiberglass,i don't see a huge problem using it in the weight pocket,i mean there's a window right next to it,what would be the advantage of ''super insulating'' that?

i would just air seal the trim to the back of the sheathing and fg the rest


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## Windows on Wash (Aug 30, 2011)

Tom Struble said:


> well if the rest of the house is fiberglass,i don't see a huge problem using it in the weight pocket,i mean there's a window right next to it,what would be the advantage of ''super insulating'' that?
> 
> i would just air seal the trim to the back of the sheathing and fg the rest


+1

Just air sealing it is going to pay huge dividends and fiberglass (while complete crap) isn't that bad if there isn't moisture or air movement.

:thumbsup:


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## HomeSealed (Jan 3, 2008)

I agree with WoW and Tom... I don't see where anyone suggested adding fiberglass alone.


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## mferguson0414 (Jan 6, 2009)

So I tore into the left side of the window today. There is absolutely no insulation between the window and the frame and obviously in the weight pocket. I really have no idea if this is going to lower the sound from the road, but I will feel better knowing there is insulation all around the window when I'm done.


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## HomeSealed (Jan 3, 2008)

You are definitely doing something worthwhile regardless of whether or not it gives you the sound reduction that you're looking for.


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## Gary in WA (Mar 11, 2009)

I thought other readers might benefit from the "stuffing f.g." in a cavity- not the professionals here.

Gary


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## mferguson0414 (Jan 6, 2009)

Took GBR's advice.


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## Gary in WA (Mar 11, 2009)

Better to start 2 new threads on the subjects. One in "General discussion" and the other in "Paint". Thanks, Gary


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