I wanted to find out if anyone has used an exterior fixed frame (picture) window for control rooms?
I am getting quotes for glass and the prices are very steep, for a 48"x48" window (2 glass, laminated) I am getting quotes for about $600 - $650 range.
So, I was thinking about using a good quality fixed frame or picture frame window. I called Lowes and they recommended Pella's low E coated window that is suppose to have 2 layers of glass. The price for 48"x48" is $310.
How much of a difference in isolation will using a standard window make vs a custom built angled glass window?
By standard window, I meant energy star rated windows, that are claimed to have better weather seals etc. They also have double glass constructed windows.
I am not planning to completely sound proof it from the CR, may be I can get two of them and install them with couple of inches seperation?
Shaz, please update your profile with your location, that way in future people don't have to ask before they can give recommendations - thanks...
Windows work just like walls, floors, ceilings, etc - as far as the physics goes, one center of mass is not enough, two is just right, the more space between them the better; and 3 or more just makes things WORSE for isolation. If you put two double glass windows in between CR and live room, you now have a 4-leaf wall where your window is, and will get really POOR isolation. It's no different in principle than walls, as I said - if you check the bottom of this page
Please look at the 40 dB wall and the 63 dB wall - note that both use the exact same amount of material, and that the one where there are only two centers of mass has 23 dB better isolation - compare that scenario to yours, replacing each double glass window with one of those standard stud walls, and you'll see wny your glass should NOT be done that way... Steve
Thanks Steve, this makes sense. Now, I have a few more questions, these might have been answered before, but I want to make sure I get this right:
1- How bad is tempered vs laminated glass? I guess it's better than using a single standard frame window right?
2- Can I use two SINGLE glass standard framed windows, mounted on two seperate walls, seperated by a few inches? Besides the visibility issues, how will it work?
3- How do you calculate the angle of the two glasses in the window?
4- How do you come up with the size of the glass? I'll have a 48"x48" opening. I am planning to have two walls on 2x4's with insulation and 5/8" dry wall mounted on resilient channels on each side. (I guess, if I have the angle then I can just use simple geometry to calculate ...)
5- Using 1/3 the width of the drywall method (atleast that's how I think it should be ...) I was planning to use a 3/8" and a 1/4" glass for the configuration I mentioned above (I know 5/16" is recommended, but I can't find it and I am sure it is way more expensive)
1 - Tempered and standard glass, close to identical acoustic properties, tempered is much safer though.
2 - Sure, this doesn't violate the mass-air-mass concept - thicker glass is better, more space between is better. Splaying (in this case) will do little for you, and hurt isolation by narrowing the gap.
3 - See #2 - if you have more than maybe 8 inches to use, you can consider a splay of 6 degrees total - this is roughly 1 inch in 10, so a 36" tall window would need about 3.5" of splay. See how quickly this eats up your air gap?
4 - First, a so-called standard 4040 window (meaning 4'0" each dimension) is based on a rough opening in the framing of 48" each dimension if I remember correctly - this means the actual window is less than that by about 1-1/2 inches. Measuring the actual products is the only way to NOT make a mistake here - also, if you insist on splaying (I've not been convinced this helps acoustically, it's more for avoiding glare - although it could help with reflections off the glass if done as part of the room design) it will be easier to do both sides the same angle - that way, both glasses can be the same dimension. Keep in mind that different thickness in panes will help isolation quite a bit, so two identical windows isn't the best approach here.
5 - Sorry, ignore the last part of (4) - yes, 1/3 OR MORE of gypsum thickness for each side is best - more won't hurt, less will DEFINITELY compromise the wall iso... Steve
