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Question regarding rigid fiberglass in control room window.
Old 3rd August 2020
  #1
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Question regarding rigid fiberglass in control room window.

I am close to having the two window panes installed between my control and live rooms.
The wall assembly is dual separated isolated walls (both insulated) with staggered studs, with airspace between, built to Rod's spec.

I am currently working up the recommended rigid fiberglass trim pieces that will go between the two inner wood stops. My question is how tight should the fiberglass fit between the two wood stops? Rod does suggest it be tight.

As of now, I have them cut so they fit very snugly in that space as suggested. Is there a such thing as too tight of a fit? I feel it is good to go but I am looking for some real world opinions just in case.

Also, is the rubber seal between the separate window casings necessary for anything other than the prevention of dust settlement? It seems to me that the fiberglass would be fine to prevent that, considering how snug the pieces fit and that I will be applying an adhesive to keep the trim piece in place at the window's top gap. Also the structures have been up for a while now, and I feel most of the settlement has happened already.

Thanks very much, in advance for any help!

Last edited by thruhiker; 3rd August 2020 at 05:29 PM.. Reason: Clarify my point
Old 3rd August 2020
  #2
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Kyle P. Gushue's Avatar
Im confused by your description of the wall. Is it 2x staggered stud wall frames?

The fiberglass should be fairly snug, you don't want it falling out. You can bevel the inner edge of the stops to hold it in place, or cut little angled extensions to do this. You can friction fit the fiberglass too, but make sure its in there good. It shouldn't move with gentle taps or tugs. With beveled stops the size/tightness of the fiberglass is less critical.

The rubber keeps a continuos seal within the window cavity to help prevent moisture condensation. You notice Rod mentions placing some decacent under the fiberglass.
Old 3rd August 2020
  #3
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Hi Kyle. Thanks for the reply! Good to know I'm on the right track.

Yes my wall is actually 2 adjacent but separate walls, both insulated, staggered studs. Double Sheet rock only on the outer sides as described in figure 4.10 and 5.2 in Rod's book.

I'll look into the rubber seal. I admit I'm not sure what type of rubber seal to use. Is there a special type I should look into? Maybe a foam rubber weather stripping type seal? Any suggestions would be appreciated. Whatever has the least chance of transmitting vibrations and sound. It sounds like it won't be a issue from what I've read, but again, I'm a bit unsure of that part. I definitely want to incorporate the dessicant.

Thanks a bunch!

Last edited by thruhiker; 3rd August 2020 at 07:28 PM..
Old 3rd August 2020
  #4
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Kyle P. Gushue's Avatar
Quote:
Originally Posted by thruhiker View Post
Hi Kyle. Thanks for the reply! Good to know I'm on the right track.

Yes my wall is actually 2 adjacent but separate walls, both insulated, staggered studs. Double Sheet rock only on the outer sides as described in figure 4.10 and 5.2 in Rod's book.

I'll look into the rubber seal. I admit I'm not sure what type of rubber seal to use. Is there a special type I should look into? Maybe a foam rubber weather stripping type seal? Any suggestions would be appreciated. Whatever has the least chance of transmitting vibrations and sound. It sounds like it won't be a issue from what I've read, but again, I'm a bit unsure of that part. I definitely want to incorporate the dessicant.

Thanks a bunch!
There's no clear advantage to a double staggered stud wall, so if you want to you can take some of that extra lumber and use it elsewhere in the project, like framing for acoustic treatment. It won't necessarily hurt anything to leave it, its just not most efficient use of materials.

For the seal ive used shower pan rubber, which was reccomended to me by max dearing owner of dark pines studio, which is featured in the book.

Previous to that i used "window tape" which is a wide sticky tape used to seal exterior seams. I used Pella brand.

I installed it so there was some "play" in the middle, the rubber/tape was not stretched out tight between the walls.
Old 3rd August 2020
  #5
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Well, the walls are already built, insulated and sheetrocked and green glued and noise sealant applied to sheetrock gaps, so I guess I'll go with it. LOL But good to know for future reference if I expand in some way.

I"ll definitely check out the suggestions for the window gap between the wall.

Thanks again, you've been a great help. Much Appreciated!
Old 3rd August 2020
  #6
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Kyle P. Gushue's Avatar
Quote:
Originally Posted by thruhiker View Post
Well, the walls are already built, insulated and sheetrocked and green glued and noise sealant applied to sheetrock gaps, so I guess I'll go with it. LOL But good to know for future reference if I expand in some way.

I"ll definitely check out the suggestions for the window gap between the wall.

Thanks again, you've been a great help. Much Appreciated!
Best of luck with your build!!
Old 13th August 2020
  #7
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Thanks Kyle!

One other question, how much desiccant should I use? Basically, is there a such thing as too much? Especially if the window will be in place for a long time with no way to recharge the dessicant once the window is installed.

Thanks!
Old 13th August 2020
  #8
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Kyle P. Gushue's Avatar
Quote:
Originally Posted by thruhiker View Post
Thanks Kyle!

One other question, how much desiccant should I use? Basically, is there a such thing as too much? Especially if the window will be in place for a long time with no way to recharge the dessicant once the window is installed.

Thanks!
Im not sure, ive never used it in a build.
Old 4 weeks ago
  #9
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Smile

Thanks again! Should I use an adhesive like 3m 90 to adhere the piece top piece? Also, should I add extra support via tacks or screws? You know, in case in 10 years it suddenly falls down inside the glass pieces. Basically would screws, with a washer on the outside of the fiberglass, attached in separate window frames compromise any isolation. Resonance, etc.
Here is a pic of the frame. And the separation
Thanks!
Attached Thumbnails
Question regarding rigid fiberglass in control room window.-20200819_131112.jpg  
Old 4 weeks ago
  #10
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Kyle P. Gushue's Avatar
I would bevel the inner edge of the stop, or add a little extentsion lip to it. Ive done that, and friction fit them, in different windows and neither method showed any signs of movement over 8 years. I haven't checked the studios for a few years, but i feel pretty confident its still fine.

The window with the beveled inner edges has a cleaner look. You can remove the stops and bevel them, or add a beveled piece to it. Even half round could work. Or corner bead. Anything that creates a lip.

Your frame looks excellent.
Old 3 weeks ago
  #11
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Quote:
Originally Posted by Kyle P. Gushue View Post
Your frame looks excellent.

Thanks. I've had a great contractor who hasn't balked at all the special things I've asked for.

One more question, the window has been installed and I feel, confident that it is airtight, however there is a gap between the edge of the glass and the window frame around the edges. Should I fill these gaps with green glue noise sealant, just to be safe, before I apply the final trim to the outside of the window assembly?
Here is a pic of some of the gap between the glass edge and the frame is yet to be trimmed over. The gap is indicated between the lines I added. I have Installed two 1/2" pieces of tempered glass, they are equal to the required wall Mass on one side and a bit thicker on the other side. It's thick and seems to be doing a good job with isolation thus far but don't want to skip any thing that could help, like the noise sealant.
Thanks very much
Attached Thumbnails
Question regarding rigid fiberglass in control room window.-20200822_083830.jpg  
Old 3 weeks ago
  #12
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Kyle P. Gushue's Avatar
I can't tell much from the pics, but assuming the glazing tape creates a perfect seal then in theory you dont need anything more. Ive done perimeter caulking on some windows with 100% silicone caulking. Ive also left one window without it. While i haven't been back in a few years both studios didn't have any issue while i was there for 5 years. The other was for a client whose studio i didn't work at and that was one of the caulked ones.

The caulking won't hurt, it would make removing the glass a bit more difficult since you have to score the caulking with a razor. Not a big deal. Just be sure to paint the surfaces first, or use paintable non-hardening silicone caulking.
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