Question on Control Room Window.

Hi John - in your control room window design on the SAE site, I didn't see any reference to treating the gap between the two sills. Should the gap be filled with caulking or left open and covered with 703? Thanks Kevin.

You fill the gap with soft fibreboard covered with a thin layer of insulation and then covered in cloth. see attached drawing cheers John

Kevin - here's how you make the fiberboard panels. You can use this technique for making ceiling panels as well. If you look at the treatment under the speakers in this picture you can see how you can make this treatment quite decorative by making panels at 45 degrees cheers John

Thanks John. Kevin.

You fill the gap with soft fibreboard covered with a thin layer of insulation and then covered in cloth.

What do you consider to be soft fibre board? The only thing I can think of that fits this descrition is acoustic ceiling tiles. Is there another product? Regards Simon

Simon - in aussieland you and I call it canite.:) cheers JOhn

Now that I've got the quote thing sussed out and edit previous post..

Simon - in aussieland you and I call it canite

Is this what is used for suspended ceilings? I've heard of canite but don't believe I've seen it. What is its typical application? Regards Simon

What is its typical application?

notice boards. I'm sure Mitre 10 has it. cheers john

John....... Another question -- is there actually a preferred spec for the angle of both panes of glass? At SAE and in Jeff Cooper's book, they don't actually specify a preference.

It depends on how wide the window jam is really. I'd go for as much as you can get within your jam, (sill) :) cheers John

Sorry to be an annoying Pom but what is soft fibreboard in the UK, anyone? Cheers Oliver

Hey Oliver - no need to apologise for being a Pom - my grandparents on my father's side were a poms from Surrey and my mother a Geordie. :) I'm not sure what you call it but it's the same as the stuff they make notice boards from and can stick drawing pins into, usually painted white on one side. Hope this helps. cheers john

A Geordie, Why, aye, man!! You're practically a Pom yourself :o What part of Surrey. I live in the next county, Kent. thanks I think I know the stuff you mean. Cheers

John Sayers wrote:

It depends on how wide the window jam is really. I'd go for as much as you can get within your jam, (sill) :) cheers John

According to the contractor, there is no need for any support from the window pane itsefl, as the frame above is solid, so in practical terms, does this mean I would want as far apart on the top jam and maybe only 1-2 inches apart on the bottom jam? (That's a fairly steep angle since the jam itself is more than a foot in width!)

No, that's a bit extreme Bruce. :) cheers john

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!

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

That helped a lot! Thank you Steve!