I would like to soundproof my ceiling without ripping down the old ceiling. The reason is that the old ceiling is holding up cellulose insulation. The cellulose insulation does a good job reducing conversation noise and keeping in heat.

I have done some research on soundproofing for footfalls from an above apartment. It is suggested that you use two layers of drywall connected with green glue or a material like quietrock and that you attach this to the joists with sound clips, which essentially detach the ceiling from the joists.

Typically it seems you are suppose to rip down the old ceiling and just start from scratch. After thinking about it, I don't see why you can just attach the clips to the joists without ripping down the pre-existing sheetrock. The ceiling will still be detached and you will have an extra layer of sheetrock to reduce noise. Am I missing something here? Also, if you must attach the clips directly to the joists, couldn't you just remove little sections of the drywall to expose the joist? The clips + the drywall furring channel should drop the new ceiling far enough not to hit the existing ceiling?

Any feedback would be greatly appreciated. Thanks

 

First, keep in mind sound reduction is possible but sound proofing is usually beyond reasonable to achieve.

More mass will help, so more sheetrock should dampen the sound transmission. Personally, I have no experience with the 'clips' you mention.

 

You said the magic word....."apartment". If this is a rental, you will need to get the landlord involved, or at least get permission in writing before you tackle this.

 

My family owns the building

 

In a retrofit installation, you would need to attach sound isolation clips using longer screws than normal to account for the added thickness of drywall that you are going through. You'd install the hat channel perpendicular to your joists. After that, you'd install r-6 fiberglass (the kind used to wrap ductwork) to deaden the space between the 2 layers of drywall. It helps deaden the reverberation that will occur in the airspace between the 2 layers. You would then hang your 5/8" drywall perpendicular to the hat channel, ensuring that no screws contact the wood framing.

If you absolutely can't remove the drywall, that'll be your best bet. If you'd like some diagrams, just google: "How To Install Resilient Sound Isolation Clips". The first website has some nice ones to help you picture what you will need to do.

 

Resilient channels with long screws to attach to the joists but short screws to hold the new rock to the channels would be one step less than isolation clips and hat channel.

 

Thanks

Xsleeper....when you say "if you absolutely can't remove the drywall" it implies I should. The only difference I see though is that I need to use longer screws for the clips. What would be the benefit of removing the existing ceiling?

 

The guys I have spoken with say that you will get better STC ratings if you remove the drywall. Seems like 2 layers would be better, I know. But when the layers are close together, they each reverberate certain frequencies, like a speaker.

 

Regular fiberglass insulation is all but useless for sound control. Use Roxul AFB mineral wool batts. The stuff is expensive but it is designed for sound attenuation and it does work far, far better than fiberglass.

 

Furd, I think you are thinking of something other than what I was suggesting. I wasn't referring to fiberglass batts. See this link for an example. Roxul insulation would work too (their sound deadening properties are almost equal), just as long as it is 1 1/2" thick to fit in the space between his two layers of drywall. This is the sort of stuff they would use for sound dampening.

 

I installed regular unfaced fiberglass batts in the dining room ceiling in a re-do a few years back, but not in the LR ceiling. In the MBR, which straddled the wall between those rooms, you could hear every sound in the LR but nothing from the DR. In the DR, no sound from the MBR. In the LR, some sound - footsteps, mainly.

There may be better sound-attenuation materials available, but I found this to be an effective and cost-effective solution - where I remembered to install them!

 

Fortunately we have data available to us.

Fiberglass insulation is the material of choice. It is urban legend that mineral wool is better than fiberglass for soundproofing. Look up the NRC study IR 761 for the raw data.

You want to remove the existing drywall to maintain a single air cavity as previously mentioned. In the event that you cannot, there are other steps to take.