1. Our master bathroom is above the theater and I couldn't move the pipes elsewhere. The laundry room is above the Equipment room/closet in the back of the theater room. As I've been spending a lot of time in the theater now, I can hear every flush and draining and the washer.
So, what can you do to help reduce water draining noises with pipes in walls inside the HT? Will this be minimized once the insulation and sheetrock goes up?

2. Some drywallers have suggested going with 5/8 instead of 1/2 drywall for the basement ceiling to help soundproof a little bit. Another guy today, however, said that 5/8 actually makes the sound situation worse. So who's right? Is it worth the minimal extra expense to put 5/8 up instead of 1/2?

3. My cans are already up in my theater room. If I decide to splurge and do double drywall with green glue, will they have to be removed and reattached or can you just use longer screws to put the finish on after drywall?

Longer screws for the second drywall layer.

Tech tip: Instead of GG try silicone between the drywall sheets ( the clear automotive product mechanics use ). Almost all acoustic installers use this product in our company. The rubbery material does a killer job of sound proofing.

Automotive silicone? Any name brands or more specific info you can point me to? How much do you use per sheet? Cost?

Instead of GG try silicone between the drywall sheets I'd never do that in my house.
Although I'm curious exactly what brand/type this automotive product is.
I suspect it might be the stuff they put on sheet metal in cars to make them quieter (a damping product of some sort) -- in which case it won't work as well in a drywall sandwich as green glue damping does, and the automotive product may be toxic or illegal inside the house.

Some drywallers have suggested going with 5/8 instead of 1/2 drywall for the basement ceiling to help soundproof a little bit.They're right.
Has anyone asked if your ok structurally to put up another layer of drywall on the ceiling?
It's impolite to be showing a movie to a half dozen beer buddies, and turn up the subwoofers, and have a 16x16 foot section of ceiling fall on them (over 1000 pounds if it's two layers of 5/8" drywall, not including whatever else falls).

Another guy today, however, said that 5/8 actually makes the sound situation worse.He's wrong.
The mass law says doubling the mass of the wall system raises the sound transmission loss by 6dB. The mass law represents the optimum/best you could possibly get -- there's a few things that'll keep you from getting that much, including of course sound going through the light cans instead of being stopped by the existing drywall.

Assuming your existing ceiling drywall is 1/2", then using a different thickness (e.g. 5/8") can reduce the coincidence dip in the sound transmission. Or to say the same thing a different way, two different sizes of drywall are a good thing, but it's a minor good thing in a frequency region that your drywall does a good job at anyway, so you don't care.

However two layers of 5/8" with green glue are even better than two different sizes of drywall -- assuming the sound doesn't just flank around it (through the walls, HVAC, cans, doors, etc).

Is it worth the minimal extra expense to put 5/8 up instead of 1/2?That's a whole other question. Beats me. Depends upon other things in your room.

If I decide to splurge and do double drywall with green glue, will they have to be removed and reattachedThe cans I've seen would have to be removed and re-attached. Cutting a hole in drywall tends to leave an uneven/imperfect hole, and the rim of the can nicely covers that imperfection. Also, if you drywall over the rim of the can, and something goes wrong with the can, you'd have to remove all your drywall to get to the can to fix it.
Note that many can's are designed to fit into one layer of drywall, not two layers. So that's something else you'll want to look at (possible new cans).

The usual possibilities are:
a) no change, because you'd have to buy new cans
b) no change, because you think you're ok
c) new 5/8" drywall over whatever drywall you've got now.
d) new 5/8" drywall over whatever drywall you've got now, with GG between.
e) RSIC or Kinetics ICW decoupled ceiling, with two layers of 5/8" drywall with GG between

That's just a list, not a recommendation, nor a requirement. I've got no clue what's best for you.

How far to go depends on your budget, and how much sound flanks through other paths.

So, what can you do to help reduce water draining noises with pipes in walls inside the HT? Will this be minimized once the insulation and sheetrock goes up?The question is how much will you be able to hear it? And again I don't know. It depends on how loud it is now, what you end up building between it and you, and if it's decoupled. One guy removed his plastic drains, and put in heavier ones, and wrapped those in pipe insulation and MLV -- probably overkill.

Wrap the pipes with damping material, insulate the ceiling, and use the 5/8 drywall. If you're going to use 2 layers, stick with Green Glue. The silicone MAY work OK for vocal range, impact type noise, etc. but I seriously doubt it will provide much of anything in the bottom end range.

Bryan

Thanks so much for the detailed responses ... decisions, decisions, decisions! This would be so much easier if money weren't a factor!

The silicone MAY work OK for vocal range, impact type noise, etc. but I seriously doubt it will provide much of anything in the bottom end range.


How can you guys makes statements like this without any testing? It always amazes me at how much people on this site know without any research or testing--truly amazing.

Person99,
I believe if you investigate you will find that he has in fact done a lot of testing.

I found out with my theater that just wrapping the pipes and putting in the insulation did a lot to reduce the annoyance. I haven't put up the DD and GG yet, but I'm sure that will make things even better.

[QUOTE=BasementBob]I'd never do that in my house.
Although I'm curious exactly what brand/type this automotive product is.
I suspect it might be the stuff they put on sheet metal in cars to make them quieter (a damping product of some sort) -- in which case it won't work as well in a drywall sandwich as green glue damping does, and the automotive product may be toxic or illegal inside the house.

They're right.
Has anyone asked if your ok structurally to put up another layer of drywall on the ceiling?


The brand of silicone is from GE and does not contain any 'rapid curing agents' which smell like vinegar and would be toxic during the drying phase. The product is used liberally in homes during regular construction for a variety of uses in electrical applications.

GG is a relatively simple formula to duplicate at a fraction of the cost but to avoid arguments I will stop right here on this subject.

Basementbob is right about the drywall issue as 2 sheets of 5/8 material is extremley heavy.

Bpape seems to have a lot of knowledge in this area so he is more qualified than myself for the technical issues.

king_arthur, what did you wrap the pipes with?

From what I've read, bpape seems like he's about as knowledgable as anyone around here, with me being at the end of the spectrum, of course!

Mr.Write,
You may want to take a look at your cans before you decide to replace them. Many cans have three screws on the inside of the housing. Loosen these screws and the housing can lower up to 1-1/2". If you take out these screws, you can temporarily remove the housing and access the junction box in case there is ever any wiring problem.

I'm sorry I wasn't very clear. This is an unfinished basement that we're finishing. I hear the pipes, draining water, etc., from the finished area above the home theater because I'm in the theater spending 9 million hours trying to figure out how bad my room's gonna suck when I put the rear surround speakers 2 inches outside of the recommended area, etc. and etc.

Anyway, my electrician put up the can boxes already and I didn't tell him that I might do double drywall or resilient channel. That's why I'm wondering if he'll have to remove those and have them hang lower somehow ... or if you can just use longer screws to attach the trim of the can.

Sorry about the confusion. All of your resposes have been good, though, thanks.

If you have those screws on the can, then you can leave them where they are at and lower the housing the additional 1/2" for the second layer of drywall.

[QUOTE=BasementBob]I'd never do that in my house.
Although I'm curious exactly what brand/type this automotive product is.
I suspect it might be the stuff they put on sheet metal in cars to make them quieter (a damping product of some sort) -- in which case it won't work as well in a drywall sandwich as green glue damping does, and the automotive product may be toxic or illegal inside the house.

They're right.
Has anyone asked if your ok structurally to put up another layer of drywall on the ceiling?


The brand of silicone is from GE and does not contain any 'rapid curing agents' which smell like vinegar and would be toxic during the drying phase. The product is used liberally in homes during regular construction for a variety of uses in electrical applications.

GG is a relatively simple formula to duplicate at a fraction of the cost but to avoid arguments I will stop right here on this subject.

Basementbob is right about the drywall issue as 2 sheets of 5/8 material is extremley heavy.

Bpape seems to have a lot of knowledge in this area so he is more qualified than myself for the technical issues.

Well, politely, you wouldn't find GG to be a simple formula to re-create at a fraction of the cost. It is no off-the-shelf material, but something very specifically engineered for this use (and really no other).

Silicone/rubbery materials don't tend to make good damping materials as they are usually (especially silicone, and most rubbers) very elastic, not viscoelastic. Off-the-shelf silicone isn't necessarily less expensive than GG, either, and specialty types can be quite expensives.

Damping materails in cars are sometimes very crude - just some rubbery gooey stuff sprayed on - but more and more they are true viscoelastic materials.

Painted-on materials can work wonders on sheet metal pieces in cars, but isn't effective on stiff/massive structuresl ike drywall. And there are GG-esque laminated steel prodcuts that are used in cars as well. Those are sometimes formed with particularily soft/malleable grades of steel to enchance performance. The new Ford pickups utilize the laminated metal, and i believe the new GM pickups (for this year) utilize a sprayed on type of material. Both can be effective, costs can vary and all of that.

Also, remember that the large expanses of sheet metal often found in cars are extremely, extremely low in damping, and almost anything can help. Typically a piece of "free" steel will exhibit damping of ~0.001, and a rubberish coating may raise that (thin, lightweight) steel to maybe 0.05 a nice change, but an assembled wall will have dmaping at primary low-freq resonances 2 orders of magnitude higher than the free steel, and will be vastly less affected by low-damping materials.

It takes alot of damping to raelly force a big change in the behavior of a wall.