Sound Proofing ideas needed please.

[kiwiaudionut]

I'm gathering ideas before constructing a home theater in my basement and have been reading about sound proofing. The most common scenario seems to begin with treating the room from the bare studs with acoustic batts, then an absorptive sheet rubber sound barrier, then sound isolating clips (SIC) with hat channel, followed by 5/8 drywall.
The room I intend to use is already fully finished with standard construction practice drywall techniques and I really did not want to tear that all down unless my idea will not work.

I can access the rear of the two interior walls and ceiling that are facing other rooms and install the batts insulation, allthough the ceiling would have to be a blown in product, so I was wondering if I could just leave the existing drywall and install the SIC clips etc over it. I would still have the air gap and floating wall created by the clip and channel setup, I would just be substituting a layer of drywall for the rubber sound barrier.

I'd love to hear from anyone with an opinion of this, and especially from someone who may have done it this way.

 

[sparky77]

I've done several remodels jobs for people, and we have use new false 2x2 walls with various types of insulation, and I cant really say any one material has worked better than another. Just be sure that if you add new studs to the wall, to fasten them very securely to the original existing studs, or you will have a resonance problem from the bass, and its likely to travel to other floors as a buzzing sound. I learned a cosly mistake from that one, and we had to refinish the wall after adding in a couple hundred dry wall screws that would reach through the new 2x2s.

 

[Johnd]

...so I was wondering if I could just leave the existing drywall and install the SIC clips etc over it. I would still have the air gap and floating wall created by the clip and channel setup, I would just be substituting a layer of drywall for the rubber sound barrier.

Positive isolation (rubber grommet) is the biggest factor in reducing db levels, unless one can build a bomb shelter. I believe the manufacturers provide specs for different construction techniques. The clip, with rubber grommet, track and 5/8 rock ought to substantially reduce the db level.

 

[kiwiaudionut]

What about doors and heat ducts?

I forgot to add: Although I'm generating many ideas for soundproofing and acoustically treating the room, I've seen nothing on doors and heat ducts !
I have a standard interior door and standard metal heat ducts that must transfer noise like a bullhorn !

Any ideas ?

 

[Johnd]

I forgot to add:
standard interior door
standard metal heat ducts

Insulated door.
Spray foam is best, insulated panels are second best.

 

[Rickster71]

Here is a link to 'Quiet Rock' drywall.
A single layer of QuietRock 525 is equivalent to 8 layers of standard drywall (acoustically).

www.quietsolution.com/

Also Green Glue.
I've used a thick layer of Silicone caulk on the studs.
Green Glue goes between two sheets of rock. (drywall)
http://www.soundisolationcompany.com/green-glue-data.php

 

[kiwiaudionut]

Thanks Rickster. The Quietrock product seems like THE way to go.
Installation ease, retrofitting over existing drywall, exceptional STC ratings, along with a lot of good information on the website (including a report on the amazing failure rate of resilient channel installations).
Comparatively, it does not sound cost prohibitive either. I can attain an STC of around 60 in this room by retrofitting with Quietrock THX. No other product I've researched will allow this without extensive remodelling.

 

[kiwiaudionut]

Okay, what about heat vents Guys. My HT target room has ceiling mounted heat and cold air returns that will transmit sound like a banshee !

 

[sparky77]

Might want to try insulated flexible ducting, something like what you would use to vent a clothes drier to the outside. As for preventing the sound from entering the ductwork in the first place, you would need some kind of acoustic trap, which I have no ideas for other than simple 90 degree bends in the ductwork to slow down the reflections.

 

[bpape]

If you want something as effective an easier to work with, consider Green Glue and another layer of drywall over the existing one. It will perform similarly to the high dollar QuietRock and is much easier to move around and hang.

Bryan

 

[kiwiaudionut]

Wow, quietrock 525 is $80 a sheet. I couldn't make myself ask what the top-of-the-line 545THX would cost. But 510 is the lowest product in the quietrock line, is $45 and has similar STC to GreenGlue (lower 50's). Lets see:
2 tubes Green glue $28, plus 2 sheets 5/8 drywall $15, is $43.
Sounds like apples to apples !

Which way should I go here ?

 

[bpape]

Which is easier to get when you mess something up or run short? Which is easier to manhandle without an extra person? Sorry, I'm a believer in the Green Glue if you couldn't tell.

Also, forgot to mention something else in my previous post. Replace the doors with solid core doors. Also, consider installing a threshold and weather stripping.

HVAC is a different story. Yes - it will ring and transmit like mad. You can damp it some but the best way is to decouple it, rout it with bends inside an isolated box, and/or cut into it and use some flex duct as one section to at least minimize the tin ringing aspect.

Bryan

 

[kiwiaudionut]

Which is easier to get when you mess something up or run short? Which is easier to manhandle without an extra person? Sorry, I'm a believer in the Green Glue if you couldn't tell.

I actually have a quietrock dealer about 30 miles from me, whereas I'd have to mailorder the Green Glue

Also, forgot to mention something else in my previous post. Replace the doors with solid core doors. Also, consider installing a threshold and weather stripping.

Yes, I've already got a handle on the door situation pun intended!Think I'll be installing a fully insulated steel exterior door complete with magnetic seals etc.

HVAC is a different story. Yes - it will ring and transmit like mad. You can damp it some but the best way is to decouple it, rout it with bends inside an isolated box, and/or cut into it and use some flex duct as one section to at least minimize the tin ringing aspect.

This is my biggest concern actually. A decoupled box with bends inside it-- Hmmmm --- not a bad idea - I'm thinkin transmission line loudspeaker! Has this box idea been tried before?

Bryan

I'm glad you are a believer in GG Bryan, it sways me in that direction hearing someone with a firm opinion. Have you used or tried 510 to form this opinion, or has someone you trust done this?

 

[bpape]

I have not tried the 510 personally. I have used the Green Glue as have many of my customers and I know it works and what to expect from it. That's important to me when I'm designing spaces. I also know and trust the research that's been done by Audio Alloy.

The numbers to me tell the story. The bottom end performance is better and I can use standard materials to get there. The rest is easy - the bottom end is what's hard.

You're fortunate to have a dealer by you for the 510. I just get tired of people quoting that marketing blurb about the Quiet Rock being as effective as 8 sheets of drywall. If you look at their most expensive and thickest product, that's what they're talking about. It's a LOT more than $80 per sheet and is so heavy that it would take about 3 guys to manhandle it around. As you found out, the thinner less expensive stuff doesn't hold up in the bottom end.

Now, in a situation where you're doing conference rooms and low end isn't an issue but the labor to put up 2 layers is, then it would likely be a better choice (and the STC numbers would be mroe applicable).

Either solution is a step up from standard construction for sure.

As for the box, that's a standard part of my room designs. Tin ducting is the Devil's work. Flex duct or duct board is MUCH quieter and housing it in an MDF box with a few 90 degree bends in it will go a LONG way to reducing transmission both ways.

Bryan