Sound reduction between condo floors
My client is in a bottom floor condo. She can hear the person upstairs walking around above her bedroom and she’d like to NOT hear that. The construction is pretty typical: 2nd story floor is 3/4″ gypcrete over 3/4″ OSB, then 2×12 joists, then “resilient channel” z-metal then 2 layers of 1/2″ rock.
I was thinking of just putting in another separate ceiling with its own framing, as the room is 9 feet tall. However, there is a sprinkler head in the room (bedroom) and I can imagine that extending that a few inches is going to be a major project. It does stick below the plane of the ceiling about an inch, so I wonder if there is anything I could do with that inch that would cut down the low-frequency noises? Perhaps ANY additional layers on the ceiling (I was thinking of perhaps some better isolating channels and another layer of rock) would be ill advised unless we can lower the sprinkler head to be flush again.
The other thought I had was that if the ceiling (and floor above) are moving with the footsteps, that they would compress the air between the old and “new” ceiling and I’d still get sound transmission. It would be a cryin’ shame to go to all that work and not have it do what you wanted.
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Any insulation in the joist cavity? I just installed 2" rock wool batts in all my party walls in my rowhouse, and it's done a great job of knocking out my neighbors late night xbox bouts. 12" of rock wool would absolutely frakkin' suck to install, not to mention having to reinstall the ceiling, but would definitely quiet things down. Also, even with RC-1 in the ceiling, if the rockers shorted it out, it's useless. If you can't drop the sprinkler, I don't think there is much option outside of opening the ceiling up and redoing it. If that is the route, then there was a good article in FH on sound proofing that is a definite good read.
Z
Just drop the sprinkler head however much you need. you'll need a sprinkler contractor but it's no big deal at all. It will take them longer to drain the system than it will to extend the head.
These ceiling acoustical problems are always difficult because it is usually the person below that suffers, but the easiest solution involves the upstairs occupant.
The best way to eliminate structure borne impact sound is to put resilient underlayment on the floor above. Since that probably isn't an option I would replace the fiberglass batts that I assume are in the ceiling with rock wool, add RSIC sound attenuation clips to the resilient channels and re-drywall with two layers of 1/2".
The reasoning behind this is that with the gypcrete and two layers of drywall you already have quite a bit of mass. What you need to improve is the break between materials, and to insure that the joist spaces themselves don't easily transfer the sound.
Good luck. These things are tricky. I find that once an occupant has been sensitized to a sound you have completely eliminate it, not just reduce it for them to be satisfied. That's a tall order.
Edit: Just a thought, but many condo associations now acknowledge the problem and insist that any time an owner changes floor coverings that they install resilient underlayment. Depending on the space above, your client might look into paying for an upgrade to her neighbor's flooring. Might be a win-win solution.
Edited 7/29/2009 4:13 pm ET by fingersandtoes
the first thing i'd do... look for air gaps... around that sprinkler pipe is one that needs to be sealed... the big gap caulks... work well... any can lights in the ceiling? even surface mount lights... the electrical box all those little 1/8 holes will transmit a ton of sound...
not much you can do to "decouple" her ceiling from their floor... short of hang'n a grid of supports for new drywall... putting a foam gasket where the new ceiling meets the walls... and using trim just below this to hide it but it can't touch it... lot of work and effort... the sprinker system if it's a DRY system then it has air pressure in the pipes not water... not a big deal to turn off the water and compressor and install a longer downpipe... if it's a wet system... then it has to be shut off and drained... then in 5 min you unscrew the down pipe and screw in a longer one... have to call the sprinkler guys... they are funny about this stuff...
next option would be to cut a few holes in the ceiling and blow in cellulose... as much as you can... might be the most cost effective fix... a large crown moulding installed after could cover all the holes around the edge of the room if planned right...
these are things that should have been addressed at the time it was built... number one reason of builders being sued on condos is noise transmission
p
Look into filling the joist space with a foam insulation. They dampen noise much better than rock wool and will seal any air gaps. Cellulose would work if dense packed. Look up green glue and consider using it to add a layer of 5/8 rock.
The walls I've seen tested don't get higher numbers when foam is used than with rock wool.
First, blow in FG or better yet rock-wool to fill the joist spaces.
Then extend the sprinkler head.
Then glue 1½" foam rubber to the gyprock ceiling, and hang a suspended ceiling below that.
To support the suspended ceiling grid while keeping it acoustically isolated from the existing ceiling: Take a few fat-profile bicycle inner tubes, cut a bunch of 1"-wide rings from them, and screw each ring to the ceiling with a roofing screw (w/its neoprene washer).
Hang the grid support wires from the rubber bands.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
The suspended ceiling appeals to me. I can see it soaking up sound from above, and being loose and not sealed, it wouldn't make a tight airspace that might still transmit vibration from top to bottom.
"The suspended ceiling appeals to me. I can see it soaking up sound from above, and being loose and not sealed,"
That is the function of RSIC sound isolation clips. They act as shock absorbers leaving the drywall layers suspended. If you look at the sound ratings of various ceiling assemblies with and without them they add significantly to both STC and IIC values.
I know people who read my responses to these sound attenuation threads might be getting sick of me saying it but sound often acts on materials in unpredictable ways. Adding things to a ceiling that in themselves seem like a good idea can often have no appreciable effect. Your best bet is to find a rated assembly with good test results and copy it. Our building code even acknowledges this and includes an appendix of sample assemblies so builders have some common walls and ceilings to chose from.
I just finished a 4 condo up grade and noise was a big complaint.
Filled the joists with fiberglass bats all we could fit into a 2x10. resilient channel with attention to no shorts and 5/8 rock. No contact on ceiling edges except foam baker rod.
worked very well.There is a new drywall that has some core in it and they claim is is equal to 8 layers of rock.I have not used it yet but I have heard good things from others. but I can't remember it's name.
Google STC ratings there is some good info out there.We did put sound absorbing underlay under the upper floor laminate flooring.
"There is a new drywall that has some core in it and they claim is is equal to 8 layers of rock."
That board is probatively expensive for all but the smallest jobs. I have to say I'm a bit skeptical too. I'd like to see it tested in a real wall assembly against 8 layers of rock. They are saying on a party wall with one layer each side you would get the same results as 16 layers of conventional 1/2"? Seems hard to believe somehow doesn't it?
Being below laminate flooring without underlay is like having a giant woodpecker living in your attic.
When you put the foam backer rod at the edge of the ceiling, how do you treat the joint? Tape like normal or something else?
I think you are talking about QuietRock. It might be his easiest option to install a layer of QuietRock over the existing sheetrock. If he can, tear down the existing stuff, install rockwool in between the joist and QuietRock over that. Quietrock is expensive stuff though.
Backer rod or acoustical sealant witch is discusting. then tape like normal. and if you do a wall, same thing keep it off the floor with rubber spacers.
Google Resilieant Channel and you can get online instructions. It is little different to work with but not that hard.
Accoustical sealant is second only to roofing goop as the most annoying building product made. Ever managed to use it without getting some on you and your tools?
Actually, in my treatment it's the foam rubber glued under the gyprock that will soak up the most sound; the suspended ceiling is 80% cosmetic. But it's important to hang the grid from vibration-dampening hanging points (hence the rubber bands cut from inner tubes), so that any vibration that does get transmitted down through the framing, gyprock, and compressed foam around the screws holding up the grid support points can't get into the wires...or they will transmit it to the metal grid and also into the air around them.
Obviously, some nice, dense acoustic-quality suspended ceiling panels won't hurt, either; you'll have the cofferdam principle working for you. If the foam rubber stops 80% of the original sound transmission, and the suspended ceiling stops 80% of what's left, the SPL level in the room below will only be 4% of what it was before...and that likely won't be perceptible.
Dinosaur
How now, Mighty Sauron, that thou art not broughtlow by this? For thine evil pales before that whichfoolish men call Justice....