I am trying to soundproof my common ceiling/floor. I recnetly had an energy audit and they recomended adding insulation within the bays. The drywall is mostly up and the current configuration is this:
Starting from the subfloor above I have 2 layers of 5/8 inch dry sanwiched with green glue between each paired of joists screwed into the subfloor. Next I have 6″ of fiberglass insulation. Than I used RSCI-1 channel holding 2 layers of 5/8 drywall again sandwhiched between green glue.
Currently it works really quite well.
I wanted to add blown in cellulose into these bays in addition to the fiberglass. I want to get as much insulation into the ceiling as I can. My only comcern is that I may lose the air space and reduce my soundproofing, which at this point takes precedent over insulation.
Next time I will add fabric between the bays and blow in cellulose, preserving the air space.
Thanks
Replies
Cellulose is a great sound dampener. IMHO, it'll improve the soundproofing rather than reduce it.
Mike Hennessy
Pittsburgh, PA
i think cellulose is very good for sound- i guess my concern would be about losing the air space- depending on how well i can control it when i blow it in there may still be an air space when it settles.The RSCI-1 channel instructions speak about keeping an airspace between the clips and the joists.thanks for your help
I don't get your concern about losing the air space--air is not as good an insulator (heat or sound) as lots of little dead air spaces in the cellulose. Mass is another thing that dampens sound very well--look how quiet it is in a basement or a house with a bearm. No air spaces there. If you had been able to fill the space with gypsum, it would have been even quieter, I'd be willing to bet.
I guess I was thinking the airspace was needed in order to maintain a separate of the ceiling/hat channel assembly from the joists. From what I understood it was the separation that created most of the benefit- so I was afraid to mess with it. I guess the cellulose would not really be a connection though.
thanks for your reply.
Yeah, I agree--don't think the cellulose would be enough of a bridge to transmit much sound.
I'm looking at sound proofing between an existing first and second floor with cellulose. I would drill holes in the 2nd story subfloor (no finished flooring yet). I am wondering if I can get away with not _packing_ the joist bays with cellulose. I was just thinking of putting only a few inches down (haven't figured how I am going to control how much I put in). I'm just looking to save money by not using so much material. thanks!
The cellulose may help reduce the noise, but you'll still have the "sound bridge" between the upstairs flooring, thru the ceiling joists, into the downstairs ceiling drywall.The best bet would be carpeting in the upstairs with a really good pad.
Before you carpet or put flooing down why not put a sound board down and then your finish floor. Did this with one of my second floor apartments and will due the other one when the tenants change.
That would probably help quite a bit. After posting earlier, I remembered using sound board inside the walls of a hall closet to "soundproof" a baby's bedroom. It wasn't soundPROOF, but it seemed to help.
I have misplaced the invoice for the product that I used. I found it at the '08 IBS and it really works well. The one apartment is over our master bedroom. Had carpeting, doubled the pad, still noisy. Used the sound board and the difference is great. 100+year old home with Heart Pine floors. Layed the sound board and put Pergio flooring over the sound board. At some point we want to restore the second floor so I did not want to do anything the would damage the floors.
Edited 8/29/2009 12:32 pm ET by GRCourter
There is also an 1/8" rubber mat that is used in walls of houses that are built near freeways. We had some leftover on a job and i put it behind the sheetrock in my theatre room and it really cuts down on the noise! I dont know whats its called but its black rubber and very heavy.
Probably its "mass-loaded vinyl" that you are talking about. Is supposed to be very good.
I think what the others suggested with carpet, sound board on floor and even mass-loaded vinyl would work better, though they would be more expensive.
Although it is not what you planned, you could use quiet rock on perpendicular strapping on the ceiling of the 1st floor. I never used it, but it looks like good stuff. Another method I've read about is to put one-by furring strips on top of the sub-floor, fill in between with sand, and then put a sub-floor on top of that. Vinyl supposedly off gases and I would stay away from it. However, if cost is the issue, filling the bays with cellulose (don't bother to do it halfway or a couple of inches), or a good thick carpet mat seem to be the cheapest, yet least effective methods.