I am planning to put up a layer of QuietRock on top of existing drywall, potentially with Green Glue between the layers for good measure. I am doing this because the wall in question is against my neighbor's bedroom wall and these condo walls are thin. Since I am going to be relocating my computer's subwoofer to my room after the job, I am probably going to need some sort of sound absorption for the subfloor. Since my room is on the second floor, bass is most likely going to travel along the floor and under the QuietRock, thus defeating the purpose. If it were on a concrete slab, I probably wouldn't have any worries.

Would mass-loaded vinyl do the trick in dampening floor vibrations from a subwoofer?

Edit: I suggest the vinyl because I am not as concerned about bass waves traveling through the floor since both of our garages are directly beneath us. It would seem that the vinyl would work in keeping waves traveling horizontally under the drywall. Knowing what to do here will determine the order in which I proceed.

2 Answers 2


Before refinishing the floor, you might want to consider using something to isolate the subwoofer from direct contact with the floor. You could try a vibration isolation riser for starters. They're a bit pricey at $50, but it's probably worth trying out before you tear out your existing floor.

  • I like that a lot. I am also not considering tearing up the floor, but rather putting something over the subfloor. Yes, I would have to tear up the carpet, but I can put that right back down. I am going to consider the riser you linked to as an additional measure of protection. Oct 24, 2011 at 17:51
  • 3
    If you're handy (sounds like it) you could try these DIY Risers.
    – joshmax
    Oct 24, 2011 at 18:20
  • Although your answer didn't address my question directly about whether or not I will need to soundproof the floor, I like your idea enough that I ordered one of these yesterday. I'll still probably use MLV, but this will most certainly help when used in conjunction with that. Oct 28, 2011 at 17:41
  • @joshmax: When it comes to home improvement, I tend to be more handi than handy. Oct 29, 2011 at 1:26

For insulating against sound between floors in our condo builds, we use the following from top down:

  • Carpeting where possible
  • Homasote on top of the subfloor
  • Fiberglass insulation in the ceiling
  • Resiliant channel to hold the drywall ceiling off of the joists (also known as sound attenuation channel)
  • Standard drywall ceiling, installed with 1" tight threaded drywall screws into the resiliant channel

I think the part you're looking for is the Homasote. If you have access to, and were concerned with, the ceiling below (which from your comments on the garage, this doesn't seem to be the case), consider the resiliant channel.

  • I just now noticed you had an answer out on this a few days ago. I talked to a Homasote rep today and am convinced that this stuff is probably the way to go as opposed to the crazy-expensive MLV. When you install Homasote, do you have to use subfloor adhesive if you're just going to screw it down anyway? I ask because I might want to put Green Glue under the Homasote and don't think a slurry mess of GG and subfloor adhesive would go over too well. It would have been nice if I asked my other GG/cement board question first so you could have put this answer there =\. Nov 28, 2011 at 23:35
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    @oscilatingcretin We use adhesive, and I believe the idea is to minimize the risk of any squeaks between the two layers of flooring and the nails. This would be less of a concern with screws. I don't have experience with GG to know if it would make a good substitute. You can try posting a new question here, but I think you'll get the best answer from the Homasote rep.
    – BMitch
    Nov 28, 2011 at 23:49

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