John Sayers' Recording Studio Design Forum Archive

Hey everybody! The studio building is going great! I have the building up and ready to start building on the inside! Only after the inspection... Hopefully that will be done this week. Anyway, I have couple quick questions...

1) Is there any figures available for the performance of double wall construction using different amounts of airspace? Would there be a major difference in STC if I were to use a 12 inch air gap as apposed to an 8 inch air gap? My current outer shell construction consists of 2x6 studs filled with blown in insulation, 7/16ths OSB, 5/8ths Sheetrock in between the studs (glued to the OSB from the inside), Tyvek house wrap and then 1/4" concrete siding. My inner leaf of the studio walls will be 2x4 studs, r-19 insulation and then 3-4 layers of 5/8ths Sheetrock. Any suggestions would be great. I need awesome isolation from the outside world!

2) A good friend of mind works for a huge glass company in town and can get me glass for dirt cheap. Anything I need. What would be the optimal laminated thickness for either side of the windows to acheive the isolation I need. My thinking is around 1/2" to 3/4". Cool, or no?

Thanks in advance to everyone. This is a great resource of which I'd be lost without!

M

1 - rough calculations (all I can do) show around STC 71 for either 8 or 12" air space, but the 12" would get roughly 3-4 dB better isolation at 50 hZ, which always helps for drums and bass. That's figured with 3 layers of 5/8 on the inner leaf, and standard house insulation filling the cavity between inner and outer leaf.

No affordable doors or windows can keep up with that, so they will be your weak link along with flanking noise -

2 - glass weighs roughly 3 times as much as sheet rock, so theoretically 1/3 as thick glass as your TOTAL wallboard for each leaf would be optimum - however, going up a notch improves (lowers) resonance of mass-air-mass, which helps low frequency TL some. Laminated is better by several dB over standard float plate glass, and you don't want both glasses in a window to be the same thickness or weight. Smaller panes give better isolation, so don't go overboard on size just because you have the money. You also want to vent the space between glasses thru some type of absorbent and into the cavity between wall leaves, this helps lessen transmission through the window also.

1/2" glass weighs around 5 1/4 pounds per square foot, 5/8 glass is around 6 1/2 pounds per square foot, 5/8 sheet rock is around 2.2 pounds per square foot, just for some examples... Steve

Thanks alot Steve! I've got a question in regards to your qoute below.

"You also want to vent the space between glasses thru some type of absorbent and into the cavity between wall leaves, this helps lessen transmission through the window also."

How would I go about this? According to all of the literature on SAE and this site, I've found nothing regarding a vent of sorts. Unless I'm totally missing something...which is probably the case. Sorry for my ignorance. Thanks a ton!

M

In the detail on this page -

http://www.saecollege.de/reference_mate ... indows.htm

the second drawing shows a gray and pink layer between the windows, over the gap between frames - it's labeled "Fiberboard covered with insulation and cloth" -

Since that was posted, more info has come to light; you want to use something for this that breathes, such as Celotex or even a thin layer of rockwool, and cloth cover that. This lets pressure buildups between windows get averaged out more by venting into the insulation area between wall leaves, and that improves Transmission Loss of the window a few dB.... Steve

Thanks Steve...You Rock - As Always!

M