Window Question????

timwheat · Post by **timwheat** » Mon Apr 18, 2005 1:19 pm

Hey, I have my studio framed and most of my materials bought and paid for, but I have a quick window framing question. I seem to remember reading somewhere that having two panes of glass was bad for some reason. I don't remember why, and maybe I'm crazy. I couldn't find the topic when I did a search and i looked for a while, so i decided to ask. Basically, when I moved into my house there was a giant picture window just sitting in the garage. Its going in the studio now, but I just wanted to make sure. Its a double paned window, 64" by 58", held together in a metal frame. Anyway, I've got epdm for the bottom and neoprene to seal the sides, I just had this nagging feeling that I was doing something wrong. Hopefully you can clear this one up for me. THANKS!!!!!!!!

Tim

Julián Fernández · Post by **Julián Fernández** » Mon Apr 18, 2005 6:32 pm

You can check out the Recording Manual! Excelent Stuff!
http://www.saecollege.de/reference_material/index.html
I found most of the answers to my questions right there..!
Hope this helps...

knightfly · Post by **knightfly** » Tue Apr 19, 2005 1:07 am

Here's the basic concept of mass-air-mass for sound isolation -

http://www.johnlsayers.com/phpBB2/download.php?id=2860

keep in mind that a double pane window is BOTH your masses - if you add another pane, or worse a double pane, this will be a 4-leaf barrier and will have multiple resonances, all of which will be weak points in the transmission loss of the window... Steve

timwheat · Post by **timwheat** » Tue Apr 19, 2005 5:05 am

yeah, I thought it was my mass air mass for that wall, I just thought that I'd read somewhere that double paned glass was no good. Its the only window in the whole place so it should be fine by itself, I just thought I'd ask to make sure before my whole studio rumbled. Thanks

Tim

knightfly · Post by **knightfly** » Tue Apr 19, 2005 12:25 pm

If it's the only window, and the only GLASS in that window, it will be slightly better than SINGLE pane glass; but not as good as two SEPARATE panes, sealed and placed with a WIDER AIR GAP between them - for some types of noise, adding a second glass will improve things (as wide an air space between them as possible) - for lower frequencies, though, a second glass may make things WORSE... Steve

timwheat · Post by **timwheat** » Tue Apr 19, 2005 2:35 pm

I think that's what I remember reading in here before, about two panes being worse in some respects. Do you think I'd be better off taking the window apart and just installing one pane of glass, or even taking it apart and making the two panes more than the 3/4" apart that they are now and isolating them from each other with two seperate epdm and neoprene seals? they're still going to be in the same wall, just a few inches from each other instead of so close and inside of their casing. This is an interior window from the control room to a drum room so we're hoping to isolate a drumset which runs the gambit of frequencies. Its also the only interior window there will be. Thanks again so much for your time.

Tim

knightfly · Post by **knightfly** » Tue Apr 19, 2005 7:32 pm

Yeah, the further apart the two panes are the better - if you can get two panes that are 1/8" spread out from 1" apart to 3" apart, the TL at 200 hZ goes from 20 dB up to 28 dB - if you can find a thicker pane for one side, it would be even better. Wider air gap would improve it even more. The two 1/8" panes 1" apart only have about 15 dB TL at 50 hZ, so the window as is won't stop much bass at all... Steve

timwheat · Post by **timwheat** » Fri Apr 22, 2005 2:06 am

Man, I just wrote out this big long thing and I don't know where the hell it went. Not on here though. OK, in a nutshell. If I build out my window frame on both sides I could probably get 8" between the two panes. Good plan right? Also, where are the stc ratings of different thickness of glass? I looked but found nothing. And finally, what formula are you using to calculate the stc of a window with different space between? I couldn't find that one anywhere too, but since I don't know the stc of my glass anyway I guess it doesn't matter. My last post was much more eloquent, but its off in cyberspace so this one will have to do. Thanks again steve

Tim

knightfly · Post by **knightfly** » Fri Apr 22, 2005 3:40 am

I "cheat" and use an older version of a demo of Insul; no longer available, the newer one is (I hear) updated to match their "for sale" version ($1000) but randomizes everything, so is useless as a tool. The older one has its limitation, some of which I've been able to work around, but the newer one is designed to make you drool enough to drop $1k and nothing else.

I don't feel comfortable spreading this version around since it was pulled from distribution by the owners, so all I can do is "guess" for people, sorry. Give me material, thickness, surface area and air gap and I'll "estimate" for you.

STC isn't your friend for music; what you want is TL values for each frequency, since lows are much harder to stop.

Building out your window frame MAY help; depends on what material you use, and whether the inner pane becomes decoupled from the outer one or not... Steve

timwheat · Post by **timwheat** » Tue May 31, 2005 6:38 pm

Ok, I've been building in this studio and have a couple of more questions about my window. I decoupled the window now and have two separate panes of glass. It turns out that its 1/4" glass 64" by 48". My biggest question is whether or not building a second wall for the two panes is the best course of action. Right now I have one wall I could mount just one pane in, or I could build another wall a foot away and mount the second pane in it. I believe the latter is the better way, but I may be losing some of my lower frequency TL iso, so I thought I'd ask. So I guess my question is: All things considered is it worth it on my TL to frame a second window a foot away from the first? There will be single panes in each frame with wallboard on one side of the frame mounted on rc, with mineral wool filling the gap. OH, the mineral wool I found is 8 lbs pcf. That's cool right? Thanks for your time.

Tim

AVare · Post by **AVare** » Wed Jun 01, 2005 12:25 am

My biggest question is whether or not building a second wall for the two panes is the best course of action.

Yes for best isolation

OH, the mineral wool I found is 8 lbs pcf. That's cool right?

that is cool.

It was terrible parsing your paragraph. If you have more questions, please compose your posts more logically.

Andre

timwheat · Post by **timwheat** » Wed Jun 01, 2005 1:38 am

Yeah, sorry, four o'clock in the morning after working 14 hours. I do believe my brain was scrambled. Anyway, I mostly just wanted Knightfly to run the numbers on my window through his fancy calculator and see if he could give me some TL numbers. I know how my walls and ceiling are going to perform so I just wanted to see what the window is going to do. THanks guys.

Tim

timwheat · Post by **timwheat** » Wed Jun 01, 2005 2:34 am

Oh, and my window is 64 by 58, not 48. Once again, the four in the morning thing. Thanks

Tim

Deluks · Post by **Deluks** » Wed Jun 01, 2005 11:22 am

Hey, this is turning into the "Knightfly's gonna sort out my window calc's for me" thread. Which is why I'm here

My first prob is replacing a thin rattling pane in a fire door, standard type, probably with a couple sheets gyproc in there.

Window is 50mm square and I'd prefer to keep it in the door, which will be used alongside another (windowless) fire door.

I've been in touch with a glazier who said he can supply 11mm laminate, or 19mm regular 'float' glass.
I also have some standard 6mm glass of my own if need be (it's free!)

My other window will be built into the stud partition approx 4" from the existing garage window (which will also need replacing)

Again I have the choice of 11mm laminate, 19 mm float or the 6mm of my own. This will be similar size to the fire door, about 50cm square.

The existing window is about 50cm wide and about 65cm high.

Hope someone can help

knightfly · Post by **knightfly** » Thu Jun 02, 2005 7:00 am

Tim, a single 1/4" pane of glass calculates to approx. STC 29, with the LF TL around 16 dB @ 50 hZ - Two such panes placed 12" apart raises it to approx. STC 50, with the 50 hZ TL @ around 26; these are both for your size glass. I'd say it's worth it... Steve

Deluks, for your door are you planning on just a single pane or one on each side of the door? And, is 4" all the distance you can get on your other window? This will really limit your LF performance... Steve