Window soundproofing

[Kevin]

I'm constructing a room in the crawl space of my house, that will be used in part for a home theather, and I want to make it as soundproof as possible. This room will have one 5040 window. Home Depot tells me that they can supply windows that have 3/16" or 1/4" thick panes, as opposed to the normal

1/8". I'm wondering if any one has experience or information as to the soundproofing effectivesness of these thicker windows?

One alternative I have considered is to frame the window opening using 2x4's in the 2x6 wall and installing a regular 1/8 pane window as normal. Then installing a second window on the inside of the 2x4 opening. this would leave an approx 2" airspace between the two windows, which could present a cleaning problem with the inevitable collection of dust in this space, (the windows are going to be sliders), and it might look a little weird. If the thicker panes are substantially effective, I think I'd would rather go that route because of the normal appearance.

I'd apprecite any comments on the thicker pane windows or the double window arrangement, and any other suggestions as to how to make this window as soundprrof as possible.

TIA Kevin

[Wayne Whitney]

Your best bet along these lines would be to get a double pane unit with the two panes of unequal thickness, say one 1/8" and one 1/4". That way the sound has to go through three different layers (each pane and the air gap in between), each of which will have a different resonant frequency, so hopefully all the frequencies will get damped sufficiently. After everything is built, you can always add a third pane as an interior storm window--again pick a different thickness.

Cheers, Wayne

[CWatters]

This site says thicker glass is better...

Quote: 1. The transmission loss is increased by 6decibels (db) each time the frequency of a measurement or the mass per unit of a single layer partition is doubled. End quote

So it would appear going from 1/8" to 1/4" should reduce noise by 6db.

Some years ago they built a motorway next to the house I was living in. I was told at the time that a 6 inch air gap beween two sheets of glass was optimum for noise reduction rather than smaller air gap used for thermal insulation.

[Glenn]

I built 2 radio stations. Stopping sound through the glass is simple. Nothing fancy like different thicknesses and all that stuff. Any glass will work. Just use 2 panes and space them uneven as in maybe 1 inch apart on the top and 3 inches on the bottom. The sound will lose itself in there bouncing around. You still need to double stud the walls etc though. I know this works.

[S. Barker]

do you live next to the airport or a drag strip? and just how deep IS this crawl space? Or did you mean to say basement?

s

[tbasc]

Glenn, What was the frame material? T

[RicodJour]

What sort of advice is that, Glenn? Simple and effective...? You're ruining our reputation! ;)

To the OP: Sound transmission follows different routes. To keep sound in use absorptive materials (think eggcrate foam on the walls of a studio), mass (dense wall materials) and construction intended to prevent structure borne sound (resilient channel and staggered studs). It's unclear whether your window concern is to keep inside noise in or outside noise out. Since your question is just about the window, you could apply a solar film to the inside pane of glass which would change its resonant frequencies, _slightly_ increase its mass, and make the surface a bit softer and therefore more absorptive. Glenn's method is good, but it sounds like you're intending to use a factory made window for a reason (looks?, ventilation when the theater isn't in use?), you'd have to use two windows (four panes of glass and three air spaces). If it's a picture window for light and view you could build the window yourself incline one pane of glass and seal the unit to prevent dust. Depending on your location and climate conditions it might be better to have an insulated unit made for the interior, incline it a bit, and add a thicker pane of glass on the outside.

R

[Glenn]

Glenn, What was the frame material? T

1 X door jamb material. Sound through there is negligible .

The walls, we used 2 X 3 KD studs 16" oc but in 2 separate walls with the studs on the facing wall in the center of the other studs. We did use a 2 X 6 plate deciding that sound was negligible too. We did insulate both 16" stud widths.

[tbasc]

Thanks, I assume you sealed plates. T