The standard 5/8" QuietRock 4' x 8' panels are about 10x the price of regular drywall - so around $90 per sheet!
While QuietRock can sometimes make sense for some very particular applications, overall, it just isn't worth the high price tag. It's rare to ever use nothing but full sheets. You almost always have to make some cuts. You might literally throw away $25 worth of material from a single panel! It just isn't worth it.
If you're just going directly over an existing wall and only using it on one small area, QuietRock can be effective and an easy way to add damping and mass. But if you can spare any amount of extra time and in virtually all other circumstances, you will be far more cost effective using standard 5/8" drywall and some damping glue that you apply yourself.
QuietRock is nothing more than pre-made panels of gypsum and damping glue (and sometimes metal in some of the thicker panels). So you can most definitely make your own damped drywall just using standard, cheap drywall and damping glue.
The easiest thing I can do is point you to
www.soundproofingcompany.com Read all of the articles and library at that site and you should gain most of the soundproofing knowledge that you're after. Call them on the phone and discuss your plans with them. They are experts. Soundproofing is all they do! And you can buy your soundproofing products from them at a discount if you call them on the phone
I'd also highly recommend that you read through the
Acoustics 101 documents from Auralex. Please make note that the Acoustics 101 stuff was written before the damping glue products such as QuietGlue and GreenGlue were on the market and before they had reputable lab test data on such damping products. But the general ideas, concepts and construction techniques still apply. Simply realize that instead of "Sheetblok" or a mass loaded vinyl in between the playwood or drywall, you can now use damping glue for even better soundproofing results. You can also use newer products like the
Iso-Sill system to better decouple your header and footer plates than the two layers of SheetBlok suggested in these older documents. And instead of the standard and easily messed up resilient channels, you can now use resilient sound clips with a hat furring channel for better results and far less chance of messing up the decoupling by putting a nail or screw through the channel into a stud by mistake!
The main things to know about soundproofing that can save you money are that you only need to decouple any shared partition once. In other words, if you build a double stud wall, that is already a decoupled wall. So you don't need to use resilient sound clips and hat channels to hang the drywall, damping glue and second layer of drywall. Just go directly into the studs, you don't gain anything by further decoupling. Similarly, if you have just a single stud wall and you use resilient clips and hat channel on one side, you don't need to use decoupling again on the other side. Again, you don't gain any benefit from additional decoupling. Just decouple once to save yourself money and square footage!
The other main thing is that much of the time, all of your hard work in building decoupled, damped, insulated, massive walls can be easily defeated by flanking noise. That's noise that travels through your HVAC ducts, through small gaps that weren't sealed, through doorways and windows, through electrical outlets and plumbing pipes. If you really want proper soundproofing, you really have to focus on addressing every possible way that sound can travel into and out of your room!
So read up, call the folks over at soundproofingcompany.com and best of luck! It can take some time and a bit of extra cash, but it's WELL worth it if you can manage to build a truly soundproof room for your home theater!
