Replies

1. 
   ki | Apr 24, 2010 10:05pm | #1

   you r on the right track

   yes remove existing drywall, safe and sound the cavity, use isolation clips, max. span for those is 48", with the clips you use steel furring channel, it snaps right in , then 2 layers of drywall with some acoustic glue between the layers. you can go a step further and lay some rubber sound deadening under the carpet upstairs too. this combination is what i do when converting basements into rental units and everyone is happy. even the fire marshall who wants his 30 min fire rating between units

2. 
   Scott | Apr 26, 2010 12:52pm | #2

   What Ki said. ... but don't

   What Ki said.

   ... but don't expect a miracle. Sound "proofing" is a stretch; sound "reduction" is closer to the truth. The best solution is to pour 1.5" of gypcrete upstairs.

   With the method you describe, you'll still hear heel thumps from above on the upstairs floor, and loud noises will pass both ways.

   We did insulation between joists, rez bar, dona cona, and drywall. Dona cona is that cheap, lighweight particle board that crumbles easily, but it has good acoustical dampening properties.

3. 
   TedWhite | Apr 30, 2010 10:44am | #3

   I agree, Ki is on the right track. RC channel is a bit problematic and I would have reservations about mounting more than one layer of drywall on this. For more drywall, you'd want a tested product like 7/8" Drywall Furring Channel, found at the same place you'd buy resilient channel. The 7/8" channel is held by resilient clips. Overall the clip system will help with low frequencies (bass) much better than RC channel.

   Scott makes an excellent point also, I think. This isn't a complete sound isolation. This isn't NASA, after all. Any soundproofing effort is going to have an advantage if it is places at the source of the noise, in this case on the floor. Installing new floors is rarely an option, so the next best method is to apply mass and damping to the underside of that subloor from below. If these's no ceiling drywall, you'd have a clear shot at this.

   Then proceed with standard R19 fiberglass (other specialty insulations will provide no advantage here). Then the clips and channels, then double drywall with damping in between as Ki suggested.

1. 
   ki | Apr 30, 2010 09:06pm | #4

   thats true you wont be able to eliminate all the noise, but you can reduce it to thumps. there is also an acoustic drywall. its supposed to be the equivalent of 7 layers of drywall in 1, but the cost in my area is $100 per sheet. the other thing you should look at is the ductwork. it is a hollow cavity that can transmit a lot of noise, even just some low conversation. you can by material to line the ducts with if you want to go crazy with it

1. 
   TedWhite | May 03, 2010 10:30am | #5

   The acoustic drywall of 1=7 has never been substantiated. They used to say 1=8. Better to use standard drywall and a damping compound in the field.

   Ductwork is a huge opportunity for sound to flank (leak) as Ki states.

4. 
   jenniferhelen | May 10, 2010 03:23am | #6

   Thanks for all the tips guys.

   I have been planning to soundproof my ceiling.

   Now I can use furring Channel and quietrock instead of RC.

    It will take me some time to do it myself.

5. 
   TedWhite | May 10, 2010 09:18am | #7

   Jennifer you would generally use the furring channel in combination with a resilient clip for decoupling. Using channel alone will help, but not be true decoupling.

   With respect to considering using a factory damped drywall, consider that any pre-damped drywall is simply layers of standard boards and damping compound. There is simply no mystery to the materials. So the decision to use these pre-damped boards comes down to: 

   Price  (less is better)

   Mass (more is better)

   Damping (more is better) 

   Generally you will always be able to field assemble a more massive, more damped and less expensive panel. An additional plus is that field assembly will allow you to overlap seams between the drywall layers.