Author Topic: What's the best of these alternatives for between floors?  (Read 3954 times)

Wayn Goodman

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What's the best of these alternatives for between floors?
« on: December 19, 2002, 10:51:51 PM »
I'm about to start a sound-reduction campaign for two apartments, one above the other.  Old 2 x 8 chestnut floor joists,sistered with new 2 x 8 spruce joists, w/wide rough pine skip sheathing as subfloor.  Here are the options I've considered:
1. Add a layer of homasote and 5/8" square-edged underlayment (the underlayment is a must) atop the existing subfloor, nailing the whole arrangement w/ring-shank nails into the joists, then suspend the 5/8" firecode ceiling (1 layer) beneath with channel wire-suspended from the joists.
2. Now that I've read some of your site, add a layer of 5/8" square-edged underlayment atop the subfloor (still nailing) and use resilient channel fastened perpendicular to the joists,  followed by 5/8" firecode (1 layer).
3. Same as 2 above, but with some sort of acoustical insulation in the joist bays AND Super Soundproof Tape on the channel faces.
My question is, what are the relative sound reduction numbers for each, and would anyone have a better idea based on the time/cost range of the above?


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Re: What's the best of these alternatives for between floors?
« Reply #1 on: December 20, 2002, 07:41:09 PM »
You are dealing with massive amounts of wood here, and hard wood at that. Wood transmits sound upwards of 1200% greater than air borne sound. When you are dealing with this much wood you need to take serious steps for soundproofing. You must de-couple the new floated ceiling from the hard wood floor and joists above.
Wayne, those joists are acting like tuning forks, and with sound passing through them at such tremendous speeds you will need to float the ceiling using either the SSP sound clips and metal furring channel (Hat channel), or with resilient channel. I would line the open cavities and the exposed joists with a closed cell foam in order to create a sealed dead air space once the floated ceiling is attached and sealed properly. Sealed dead air space is very effective for soundproofing, as opposed to having the space filled with fiber glass insulation or other non soundproofing agents. If the finances permit, I would also consider lining the back of the floated drywall with the foam too.
Now Wayne, keep in mind that the sound clips and furring channels will virtually double your soundproofing over the use of resilient channel, and the sound clips will easily support a double layer of 5/8" fire code drywall.
Lastly, you may want to add a layer of the Mass loaded vinyl sandwiched between the 2 layers of floated drywall. This will add 26 STC points to your new floated ceiling, and seeing that this material is only 1/8" you will not lose much ceiling space.
 I realize that this seems like a lot of extra work compared to your original plans, but you have to look at it like this, you want to do this only one time, and you want to do it right the first time. For more detailed information, please consult the website. If you need more help, then feel free to give us a call at the numbers listed below. Check out this link about the sound clips. Thanks Wayne.

Bob Orther
Super Soundproofing Sales/Technical Associate.
Ph: (760) 749-7049    FAX: (760) 749-6384
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