So I am getting close to hanging the sheetrock in my basement. I have decided to go with Quiet Solution rock which this version is a piece of half inch with a quarter inch of hardi-board (tile board) glued to the sheetrock with a type of green glue.

My question is about the area under my stairs. My wife REALLY wanted the are under the stairs to have a opening so the kids could play under there. As you may know, the underside of the stairs has many places where wood comes together. Would this be a good place to use green glue? On all of these 'wood joints' where the steps are constructed? I am definitely concerned about sound coming through this stairway so I need to go the extra mile with this one.

Thanks for the help.

Hi Tandy,

Quiet Rock works well, however the material in that product is Quiet Glue. It isn't Green Glue or even something similar to Green Glue. Different characteristics altogether. Look at the low frequency differential on the lab tests and that will give you an idea of how different these materials are.

Regarding the stairs, the best and first rule of thumb is to try and prevent the vibration from entering the original framing. You are right on track regarding a stairwell's liability. A stairwell is uniquely problematic, since it is significantly attached to the floor joist system, and of course the upper stairwell walls are essentially the living room walls, or whatever.

Another bugger about the stairwell is that if you have a second story, the upper and lower stairwells are generally locked together. So the vibration transmission continues to the second floor easily.

So the opportunity for vibration conduction is enormous. If you wanted to tap out Morse Code to someone far away in the house, you would be most successful if you use the stair framing to tap out your message.

Having a stairway in the rear of the theater area is very convenient, but there's a huge sacrifice in soundproofing. General advice is to put a wall in front of a stairwell to stop this.

Yikes, so not much hope with the area under the stairs?

Could this product possibly work for me:

http://www.buyacoustics.com/product_info.php/cPath/30/products_id/63

Would that solve/help the problem with sound traveling up the walls?

Also, in your first paragraph you said that quiet solution's quiet glue isn't anything like green glue. Would it be better to get something like quiet glue for this scenario or stick with green glue?

Hi Tandy,

The rubber booties you referenced are excellent for isolating floating floors. That isn't your application, though. They won't shield vibrations from hitting that stairwell. That's what a rear wall in the heater would be for.

Field assembling a wall with double drywall and glue is definitely the way to go. Heavier wall with less waste. Much more economical. Lab tests show Green Glue to be 4x as effective by volume as Quiet Glue.

Having said all of this, if you can't put a rear wall on that room and prevent sound from flooding up your stairwell, I'm tempted to tell you to just use standard single layer drywall and save the $ on soundproofing materials. That stairwell will strongly define your level of success, so it doesn't make a lot of sense to spend the coin on the walls and ceiling of the theater.

Here is a very rough drawing of what the basement looks like. Are you saying build a wall in front of/next to the stairway wall? The wall that runs perpendicular with the beam? What should the specifications of the wall be? Is the idea the sound travels up the 'extra' wall and stops in the ceiling instead of continuing up the true stairway wall... ? Lumber dimensions and sheetrock on both sides or one side--stagger the studs? Could I still keep the opening under the stairs? Maybe when I am watching a movie I could place a cover over the opening... A cover out of thick wood lined with lead or something... ?

Also, do you think it could be better to use 1/4" hardiboard, then green glue with 5/8" covering it all up?

I would definitely like to do this right.

The Quiet Solution will be for free, but hopefully I can use it to the best of my advantage if it were to be in fact the way to go...

I would recommend a simple 2x4 wall in front of that perpendicular stairwell wall you referenced. Steel Studs would be better, 24" on center with R13 fiberglass. Drywall both sides. This would seal that area under the stairwell from the theater. It is possible for you to build a plug / small door that would allow sealed access to the area under the stairs. The entire project would be more soundproofed if you deleted this area under the stairs altogether, but these things are always a series of compromises and we have to marry up what is technically good with what is practical.

The 1/4" Hardiboard is great stuff. Very dense yet flexible. It is available in 4x8 sheets for exterior siding. The downsides in this application are the cost and the fact that you can't recess a screw head into it without twisting the screw head off. So unless you countersink every screw, you'll have these raised bumps everywhere.

In these applications, you really can't beat standard 5/8" drywall. The exotic materials cost more, perform worse. If you have access to free Quiet Rock, that's great. I'd use it too. You could Green Glue two sheets of it together, or try a sheet of QR and a sheet of standard drywall. I would look at the low frequency data on the Quiet Rock before relying on it alone for sound isolation, however.

I would recommend a simple 2x4 wall in front of that perpendicular stairwell wall you referenced. Steel Studs would be better, 24" on center with R13 fiberglass. Drywall both sides. This would seal that area under the stairwell from the theater. It is possible for you to build a plug / small door that would allow sealed access to the area under the stairs. The entire project would be more soundproofed if you deleted this area under the stairs altogether, but these things are always a series of compromises and we have to marry up what is technically good with what is practical.

In these applications, you really can't beat standard 5/8" drywall. The exotic materials cost more, perform worse. If you have access to free Quiet Rock, that's great. I'd use it too. You could Green Glue two sheets of it together, or try a sheet of QR and a sheet of standard drywall. I would look at the low frequency data on the Quiet Rock before relying on it alone for sound isolation, however.

For the wall I will be building... Would it be even better to use the RSIC-1 sound isolation clips and hat channel with two layers of 5/8" with green glue in between on one side and just regular 5/8" on the other? Also, the wall I build, should it be not touching the wall that it is built in front of? An air gap between the two?

I'm starting to think this Quiet Rock is a little over-hyped. I didn't know they were a company started from some 'Noise Killer' invention in the early to mid 90s that failed with the dot com bust and sold off to a company in norther California that one day decided to put the Noise Killer in between sheetrock. Either way, the tests I read on the internet put green glue and sheetrock and the sound clips above quiet rock...

Sorry for bothering you much, the above questions are my final questions, I promise.

Tandy,

This is sure not a bother. I have some adjusted wall ideas I'll post tomorrow

Just to throw in one more question. All the exterior walls of the room and concrete. Do I need to do anything to them to stop sound? I wasn't initially worried about double layer walls on concrete walls, but is the sound just going to travel up the wood?

OK looking at this a little further, assuming reasonably high isolation:

The left wall by the stairs- can you build a double stud wall there with a door in that wall? Can you change the direction of the way that door opens at the bottom of the stairs? This would create an excellent air lock, thereby removing a big flanking pathway.

This wall would be wood or steel studs, 16" or 24" on center. Single 5/8" on the outside by the stairs, double 5/8" on the theater side. R13 in each of the two walls that together comprise the double stud wall. Green Glue in between the layers of 5/8". No clips needed, as the wall is already decoupled.

The question is how much distance there would be between the existing stairwell wall and the new wall. You could leave a small hallway to get to the area under the stairs? Not sure what space you're dealing with.

The Ceiling- You could save a lot of time, money and energy if you built your ceiling first. Use clips+channel to decouple the ceiling. Then run the ceiling drywall all the way to the concrete. Seal the drywall to the concrete. This sort of puts a Tupperware lid on the room. So the 3 walls can be single stud with a little R13 in them. No clips, no Green Glue.

Does this make sense?

OK looking at this a little further, assuming reasonably high isolation:

The left wall by the stairs- can you build a double stud wall there with a door in that wall? Can you change the direction of the way that door opens at the bottom of the stairs? This would create an excellent air lock, thereby removing a big flanking pathway.

This wall would be wood or steel studs, 16" or 24" on center. Single 5/8" on the outside by the stairs, double 5/8" on the theater side. R13 in each of the two walls that together comprise the double stud wall. Green Glue in between the layers of 5/8". No clips needed, as the wall is already decoupled.

The question is how much distance there would be between the existing stairwell wall and the new wall. You could leave a small hallway to get to the area under the stairs? Not sure what space you're dealing with.

The Ceiling- You could save a lot of time, money and energy if you built your ceiling first. Use clips+channel to decouple the ceiling. Then run the ceiling drywall all the way to the concrete. Seal the drywall to the concrete. This sort of puts a Tupperware lid on the room. So the 3 walls can be single stud with a little R13 in them. No clips, no Green Glue.

Does this make sense?

I can place a door inside the opening on the wall that will be a double stud wall, but would not be able to change the direction in which it opens. Lack of space.

The gap between the current wall and the new wall I should build is what I was wondering about. The framing for the new wall shouldn't be touching the old wall, right? Or does it matter? It seems like sound would just transfer back to the old wall if they're touching. And doesn't an air gap help with the sound... or something... ? So should the new wall be built 2" away from current wall or 4" or what? I probably couldn't built it out beyond 4 inches from the current wall without making the room look goofy.

I wish I would have known about that ceiling idea. I have already framed in a couple soffits for plumbing/HVAC and ran a bunch of speaker wire in those soffits. And built the stage for the screen and tower things for the speakers...

What about basement walls with concrete on the other side? Should they be double layer green glue or are they probably fine since they are on the exterior of the basement?

OK door direction isn't critical. But that small airlock will be excellent.

The double wall would ideally not contact the old wall. If that was a standard wall, I'd suggest incorporating it into the double wall, but I think you'll have more construction headaches than it's worth. So consider leaving a 1" gap there between the old and new. Small air cavities are generally not a great idea, so you might consider laying a 1" layer of duct liner in that 1" gap.

Have you abandoned the under-the-stair play area? That will really complicate things.

The three perimeter walls will have to be treated, since sound penetrating them will have nowhere to go but up through your floor. A classic flanking pathway.

I used RSIC clips, double drywall, and GreenGlue to "soundproof" my entire basement. I was worried about my stairway because I was not able to use the RSIC clips in that area, but I did use double drywall with GreenGlue on the inside and outside of the stairwell as well as all the way up the stairs. I am absolutely thrilled with the results. Here are some pictures of the area. The staircase is behind the bookcase...

http://home.comcast.net/~scottj0007/theater/stairs_01.jpg

http://home.comcast.net/~scottj0007/theater/stairs_03.jpg

http://home.comcast.net/~scottj0007/theater/stairs_04.jpg

http://home.comcast.net/~scottj0007/theater/stairs_05.jpg

http://home.comcast.net/~scottj0007/theater/stairs_06.jpg

http://home.comcast.net/~scottj0007/theater/stairs_07.jpg

http://home.comcast.net/~scottj0007/theater/stairs_08.jpg

The bookcase is open to the closet behind to give access to the back side of all of the equipment. Even though the studs for the stairwell go all the way up to the second floor, the sound is very well isolated. By using the two layers of drywall with GreenGlue in between all the way up the stairwell, it effectively dampens the sound from travelling to the upper levels. I can crank my sound system up to 90 dB and only the lowest of bass is slightly audible in the area directly above my theater. (I have dual SVS subwoofers that absolutely shake the theater).

(My theater is also fully "Alpha Certified" by Terry Montlick at http://www.tmlaboratories.com (http://www.tmlaboratories.com) as well.)

All I can say is GreenGlue lives up to its promise if you apply it with maticulous attention to detail and don't cut corners.

- Scott