Studio Winows

Origin Productions · Post by **Origin Productions** » Thu Sep 30, 2004 11:56 pm

Hey Knightfly,

First off, heres a description of what I'm doing for my studio window. It is a double wall (Two independent sets of framing on steal studs with an 8 inch air gap). There is two layers of drywall on opposite sides of each wall (Leaf spring leaf method). The window is 6' by 4' and I have already purchased the two differing thicknesses of laminated glass.

I am looking for diagrams and/or methods of building and installing the window frame etc. I have read a couple different descriptions of the process which described the air space between the two windows as being completly sealed and enclosed with rigid insulation glued on styrofoam and wrapped in fabric. Acoustic sealent and rubber stripping is used for tight sealing. And they also talked about using silica beads to keep the moisture inside this "chamber" under control.

What type of wood and size do you suggest to build the window frame out of? Currently the window opening is steal studs reinforced with 2 x3's. How should I fasten the window frame to this...nail or screw? And should I use acoustic sealent in between the steal studs and the window frame or is there some other technique? And where and how should the silica beads be installed?

As usual any advice is much appreciated.

James

AVare · Post by **AVare** » Fri Oct 01, 2004 7:43 am

Knightfly can anwer your query much better than I can, but it was beautiful reading your post with just about everything significant clearly written and the questions clearly explained.

Good Luck
Andre

knightfly · Post by **knightfly** » Sat Oct 02, 2004 1:06 am

Generally, the air space between panes should be vented into the insulation space between the walls - for this, either rigid fiberglass insulation or celotex can be wrapped in dark cloth (minimises light reflections) and used to surround the window frames, which should be separate as the wall frames are. If the window is done this way, silica isn't necessary in most cases. If you want, you can still use it; just place it in small bags and lay it under the cloth-covered celotex surround between inner and outer panes.

Do you have commercially made frames already, or will you build custom ones? This needs to be handled on an individual basis, because different frames are built differently - some will need filling with plumber's putty to keep voids from weakening the isolation... Steve

Origin Productions · Post by **Origin Productions** » Tue Oct 05, 2004 5:25 am

Thanks Knightfly,

I will be custom building the window frames. I've been planning on following the diagram I found on the AES website. But I'm still wondering if I should use standard window frame wood (Pine etc.) or something with extra density? Also what method do I use to get a tight seal between the steal studded opening and the window frame...should I put rubber stripping or acoustic sealent or anything else to elimante "leaks"?

If I wrap rigid insulation in cloth how do you suggest I fasten it into place? Would glueing it to the window frame be inccorect?

James

knightfly · Post by **knightfly** » Tue Oct 05, 2004 8:27 pm

Acoustic caulk will work fine to seal around the steel and the wood frames - and pine is fine, especially for separate wall frames. You just use two separate frames that don't touch each other, one for each pane of glass. Bed the glass in 1/4" neoprene and seal with acoustic caulk.

If you do a complete fill of insulation in your wall, you can just stretch black cloth around between your two window frames before placing the glass - you want the window to "breathe" into the wall cavity, it bleeds off some of the sound pressure and improves TL through the window... Steve

Shaz · Post by **Shaz** » Wed Oct 06, 2004 1:17 am

Steve,

Is the insulation/fabric between the two glass panes absolutely necessary? How is this window built at BBS? I really don't see any fabric covered insulation there.

knightfly · Post by **knightfly** » Wed Oct 06, 2004 3:51 am

I wasn't involved in Bruce's studio build in any way, so I couldn't say what was done on that window - it certainly doesn't look like any venting was done in that pic, I agree. If not, the TL through the window won't be as good as it could have been.

Looks can be deceiving, however; there may be something we're not seeing in the pic. You would have to ask Bruce about that, or maybe John.

If the enclosure for the window has ANY part that is one piece between the two sides, isolation won't be optimum.

Whether you cover up between glasses is a matter of aesthetics mostly; if you like looking at the insulation between your walls when looking through the window, no biggie - however, you do NOT want both frames of a double framed wall to touch each other with hard contact, or you lose. It's that simple... Steve

Shaz · Post by **Shaz** » Wed Oct 06, 2004 2:20 pm

Thanks Steve. I will have a double frame/ double pane window with about 1.5" of space in between, I really want the window to look nice. My contractor is building the window frames with solid oak with oak mouldings and trim.

What other materials can be placed between the two window glass panes besides insulation wrapped in fabric to cover the space? Can I use solid color (black) carpet or vinyl? I was initially planning to use plywood to cover the gap, but after reading your comments it seems like that would be a solid contact between the two frames and kill the TL, right?

knightfly · Post by **knightfly** » Wed Oct 06, 2004 9:23 pm

If TL is important to you, you shouldn't use any material that can't breathe; this keeps the window from venting into the surrounding wall space with loud sounds, and weakens the overall performance of the wall by a few dB. However, the biggest need for isolation is in the low frequency range, and even non-perforated vinyl will pass bass frequencies - so yes, this could work OK.

You can use anything that breathes, but if it's very rigid you should let it float on at least one side of the window, so it doesn't couple the frames together.

Hope that helps... Steve