acoustic drywall

mmhendrie

Guys - looking for some feedback...

Am about to re-drywall a room. One of the common walls will have a TV mounted on the other side, and Tv speakers. To do that particular length of wall will be two sheets of drywall. Questions:

1. Does accoustic drywall on one side of a wall make a big difference for sound insulation vs. a 5/8 drywall on a 2x4 frame with insulation in the wall?

2. What's a typical cost of an accoustic sheet, i assume it's more then regular, but significantly more? A 8x4x5/8 sheet of reg. costs just under $7 out my way, what should i expect to pay for accoustic roughly?

3. Any difference in hanging/mudding/tapping accoustic vs. regular drywall?

thanks much!!
-Matt

Bjamin

The only acoustic drywall i have seen so far, is super expensive. I have had pretty remarkable results using a product called sonopan with a combination of resilient channel and sound batt insulation. their website explains how to use it with resilient channel and the STC (sound transmission class) rating it has. the site is very informative about building a sound proof room.

http://www.materiauxspecl.com/en/acoustic.html and click on installation and warning .pdf file.

good luck..........

xxPaulCPxx

4x8 sheet of 5/8" accustic drywall is $35 at Lowes near me. I used it in a space where I didn't have alot of room to lose depth (a hallway). Two sheets of 5/8 and a tube of Green Glue will do you better.

Also, accustic drywall has an inner layer with a gummy adhesive - it's two 1/4" sheets glued together. This makes scoring and snapping impossible, because it now has two sheets of cardboard in the center that hinge instead of snapping. To cut this stuff, you actually need to CUT over 1/2way through the board before you can snap it off. Plus it will gum up your cutting tool.

Ted White

As Paul said, any pre-damped drywall is simply layers of standard boards and damping compound. There is simply no mystery to the materials. So the decision to use these pre-damped boards comes down to:

Price (less is better)
Mass (more is better)
Damping (more is better)

Generally you will always be able to field assemble a more massive, more damped and less expensive panel. An additional plus is that field assembly will allow you to overlap seams between the drywall layers.

Sonopan is another variant of sound board, and really has less value in sound isolated construction than you might think.

These sound board products are marketed under many different names. In general they are made from waste material from the lumber industry.

They are light weight and a bit spongy, so the hope of some sound isolation benefit springs forth.

Let's look at the physics of what is available to us in out little soundproofing toolbox. There are 4 and only 4 elements of soundproofing:

#1 we have Decoupling. Having these sound boards on our studs doesn't reduce the surface area of contact, not does it establish the required decoupled mass-air(spring)-mass system we're looking for. So these sound boards do not decouple.

#2 we have Absorption. For absorption within a defined air cavity we want a medium density absorptive material. Sound boards are far too dense for the type of absorption we need so in effect, sound boards do not offer absorption.

#3 we have Mass. The low density of the sound boards certainly don't replace drywall as they are at best 1/2 the weight of proper 5/5" drywall. Sound boards do not offer significant mass.

#4 we have Damping. While the soundboards may be somewhat damped themselves, they do not significantly damp the drywall they are in contact with. Sound boards do not effectively damp what they are in contact with.

So the sound boards find themselves in an undefined category. They arguably do a little but not to the point where we would take up valuable resources to incorporate them.

newfie49

there is a very good product out called QuietRock which I use in home theater rooms, bsmt ceilings where the owner wants no noise coming from upstairs, most drywall supply places sell it, it can get expewnsive if you use a lot of it but for small jobs its worth the $$$.

Ted White

I guess I would not agree that pre-damped drywall is worth the cost. Using standard drywall and one of several available damping compounds, you can create a much more massive and damped board in the field, as I mentioned in my last post.

More mass
More damping
Less cost

Also, the use of a damped drywall is only part of the equation. Again as mentioned in my last post

jlberkeley

you can always get some lighter, cheap drywall and sandwich some of that green glue in-between. I've also heard about hanging a second layer of light drywall using few screws but mostly liquid nails...sound travels through screws/nails. I have not tried this though, so I can't necessarily recommend it.

Ted White

The best solution always includes a great deal of mass (weight), so double 5/8" is significantly better than double 1/2".

If the drywall panels are damped, screws become your friend. Liquid nails instead of screws is risky...