Question on Control Room Window.

[JoeMilner]

Hi John
I have the opposite problem from Bruce: because of space considerations the control room wall is a single wall, with 6" steel framing. The studio is an ADR recording stage, so I don't require a high degree of isolation between the stage (studio) and control room, as I'm just recording dialog. So....a couple questions:

1) On a single wall sill, should I use 2 panes, spaced about 2" at the bottom and 4" at the top? Or is this not enough of an angle change to make an appreciable difference?

2) The window is 4'x 8'. With glass that size, what size lumber should be used for the stops?


Thanks very much!

[knightfly]

Since isolation goes to the narrowest air space, a 2" gap with 9 mm and 12 mm glass (3/8 and 1/2") will give about STC42 - probably enough for ADR, as you said. The tilt will help glare from lights some, but isn't nearly enough to completely kill flutter. For that you need at least 5-6 degrees each side, which is about 1:10, or almost 5" per side for a 48" tall glass.

Putting the glass parallel would only increase STC by about 3 points, and would worsen glare so probably NOT a good idea.

Outer stops with that heavy a glass should be at least 1-1/4" hardwood, drilled and countersunk every 8-10 inches - all glass edges should be cushioned with 1/4" neoprene, handled only with cloth gloves after cleaning, at least one side should be removable just in case, and if you can find a way to put some silica between glasses (maybe under a strip of black cloth) do it.

Since the sill will be one piece anyway, you might consider a wider sill set into the frame if you need more angle for glare control. This should be wood, not metal.

Hope that helped... Steve

[JoeMilner]

That helped a lot!
Thank you Steve!