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Making new floor/ceiling - Best way to soundproof?

Making new floor/ceiling - Best way to soundproof?

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  #1  
Old 01-15-08, 11:20 PM
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Making new floor/ceiling - Best way to soundproof?

Hi. I live in an old house that has an upstairs/downstairs. The downstairs is a suite. What we are planning to do is turn the stairwell into a small room. The stairway that runs, indoors, from the upstairs to the downstairs is about 8 feet long and 3 feet wide. Where the staircase enters the downstairs, there is also an area about 6 by 8 that will also be part of the small bedroom. The plan is to construct what will be a floor for the upstairs, and what will be a ceiling for the downstairs mini-bedroom. My concern is noise. The room will be for a child who has a tv, computer, etc. and I really am hoping to not be able to hear anything from that room. My bedroom also overlaps part of the soon-to-be downstairs bedroom.

I went to Home Depot and got their suggestions on what to use for noise reduction. They said the best insulation to use would be Roxul 'Safe and Sound'. It is approx. $35 and covers an area of 60 square feet. The boy working there also suggested I check out something called "Quiet Rock" (which Home Depot does not sell) and is about $60 for a 4x8' sheet. Has any here used it before, and is it very effective for noise reduction?

He also suggested buying something called a ResBar (which I think he also called a Resilient Channel). Does this also sound like something I should buy?

I'm not getting professionals to do the work......Instead, my brother-in-law will be doing it. He lives out of town, and wants me to have any supplies I want to use 'on hand for the afternoon he is here' because time will be limited that day, and he wants me to have everything here that he'll need. I should also mention that he is not a carpenter, so any advice I can get will be most welcome.

I should mention that this house is not soundproof at all. It's awful. I know it doesn't help that we have an oil furnance; hence, anything I even say in my kitchen upstairs can be heard in all the vents downstairs. It's awful. I know that short of changing the heating over to electric heat, there's not alot we can do to make it more soundproof, but I'm thinking that every little bit will at least help. There's places in the downstairs ceiling where some of the pipes are visible, with a couple inch gaps around them, when they sit in a hollow area between the floors. Is there anything we can do to sound proof an existing ceiling, short of taking the ceiling right down? I think we'll try and stuff up some pieces of that roxul insulation material. I'm also wondering about spraying up some of that ceiling foam stuff that hardens and acts as a bit of a sound barrier. Does that sound like a good idea?

I was also wondering about sheets of styrofoam. The boy at Home Depot said it wasn't really worth buying, and the best way to soundproof the floor/ceiling we'll be putting up would be to just use the roxul insulation and the ResBar and maybe the Quiet Rock.

I'd welcome any advice!

Thanks.
 
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  #2  
Old 01-16-08, 08:12 AM
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Hi. This is quite a common problem. Great if you can address the issue now, rather than later after the room is done.

Insulation is a great thing, but there is no practical difference in performance between standard fiberglass batts and the "acoustic" labeled materials. This is one of those times that the least expensive material is also the best. If you use a standard R19 fiberglass (either with or without the kraft paper facing) you will be just fine. Avoid the foam at all cost. Great for thermal barrier, but MUCH too rigid for acoustic, despite what they may claim. Independent lab data is very clear on this.

The Resilient Channel, also known as RC-1, the Depot fellow referred to is a partially good idea. The Resilient Channel introduces decoupling into the system. In this case, the decoupling is a separation of ceiling drywall from the ceiling joist framing. If done correctly, decoupling is a very good thing.

The problem is that (per the largest manufacturer) 85% of all Resilient Channel installations are done incorrectly (though all contractors will say they are among the 15% that do it correctly...). Some types of Resilient Channel can also sag and fail.

I might suggest that you consider installing wood furring strip every 24" perpendicular to the ceiling joists. Have the joist cavities filled with standard R19 fiberglass. Weight (mass) is an important component in stopping sound, so two sheets of standard drywall would be recommended. The Quiet Rock is standard drywall that is "damped" with a damping compound between the two sheets of drywall. Tough to cut it, so your bro-in-law might not be too pleased. Just use standard 1/2" or 5/8" drywall. If you want to take this opportunity to damp the drywall yourself, try Green Glue or Decibel Drop. Both work very well.

Seal up the perimeter with standard painters caulk.

The one thing to keep in mind when soundproofing is that sound travels via several pathways. You can install 12" of lead in your floor, but sound vibration can travel downstairs through the walls and bypass the floor. This is called "flanking." Some of the sound from upstairs will travel down this way, but most will be dealt with using the protocol I described.

Hope that helps.
 
  #3  
Old 01-17-08, 06:51 AM
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Trust Ted White.

After reading the origianl post I was about to make similar comments, until I saw Ted's name. He knows WAY more about it than I do.

Let me offer this, though. Not having an oil furnace myself, I'm not sure what your "vents" and "pipes" look like. If your system is like my forced hot air system, with round ducts leading off of a square, main trunk line, you may be able to replace some short sections of the visible metal duct work (the round ones) with flex duct (easily available at big box stores) and cut down some of the rattling throughout the house.

Good luck. As Ted says sound travels in many (and mysterious) ways.

Tom
 
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Old 01-20-08, 01:46 AM
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Thank you so much for taking the time to reply. I will definitely be passing along all of your suggestions.

Thank you! Much appreciated.
 
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