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May 5, 2008
soundboard vs. furring (firring) stips for ceiling
Renovation in progress.
The contractor has pretty much gutted the place - ceiling has been taken down in most of the rooms (the picture is of the inside of one of the ceilings that was left intact because it had no cracks etc.)
As you can see in the picture, there was no insulation in the ceiling - for sound reasons (every footstep, and even sometimes the cat can be heard from the upstairs apt) the contractor suggests putting insulation in since the ceiling is open in most of the rooms. Should I request any special insulation for sound? Or is it all pretty much the same.
I have researched soundproofing and I don’t believe the insulation will do much. It is designed to insulate heat not sound. To quiet footsteps and voices from upstairs I was looking into “green glue” (home theater DIY stuff) but it’s not available in stores and most people have never heard of it. So i was going to go with either Celotex soundboard or furring strips. Anyone know if one is better than the other? Or do you suggest something else.
Comments
I installed hydronic radiant heat in a 2 story addition and put batt insulation in the ceiling. As a side effect the sound insulation is great. I would do it.
Posted by: guest at May 5, 2008 8:51 PM
I did "Heat" insulation between the upper floor timbers, two layers of Homosote sound board, one on the raw floor timbers and one on the metal frame drop ceiling just below the main floor timbers and then two layers of sheet rock directly over that, OverKILL you say, and I can still hear upper floor squeeks and the old man on his daily bender. The more solid mass you add the better, not fluff mass, but sound is going to get through no matter what you do in these old houses.
Posted by: guest at May 5, 2008 11:15 PM
Cotton batt has soundproofing qualities that beat fiberglass.
Posted by: vanburenproud at May 6, 2008 6:14 AM
I've been installing a product called Quiet Rock on the ceiling of a house I've been working on . I think it's a good product but a bit expensive at $80 per 5/8" thick sheet. You can get it at Strober building supply in Greenpoint.
You can read more about the product at
http://www.quietsolution.com/html/quietrock.html
Posted by: Rick at May 6, 2008 6:31 AM
"Footfall noise" from an upstairs neighbor is the worst to deal with. There's a lot of energy introduced into the system, and that energy easily overwhelms a lot of techniques and materials.
#1 Install standard R19 fiberglass. If you look at the various test reports, you'll see that cotton did no better than fiberglass.
#2 Decouple the new ceiling drywall from the old wood joists. Use a resilient clip system. There are less expensive ones, and I'd recommend those.
#3 Add mass. Cheapest and easiest source of mass is drywall.I'd avoid heavy rubber due to cost relative to effectiveness.
#4 damp the drywall. That's what quiet rock does, but again, if you look at independent lab tests, the quiet rock doesn't perform as well as the green glue you first considered. Also costs a hell of a lot.
Posted by: guest at May 6, 2008 9:19 AM
Best remedy for footfalls (cats and humans) - and cheaper, too, is (1) rugs and rug padding in upstairs rooms - it is required in standard rental and coop leases, but people like that "bare wood" look and so don't enforce it, and (2) an agreement to take off shoes upon entering the apartment (with cats, this one is no problem ;-)
Posted by: guest at May 6, 2008 10:42 AM
Rick, can you comment on Quietrock 525 (5/8") vs. 510 (1/2"). There is a significant price difference, but is there is a significant performance difference?
Posted by: Ibis at May 6, 2008 11:03 AM
I've done Green Glue assemblies for several clients, and they have been really happy with the results. There are also some mass-enhanced drywall products that incorporate a layer of lead or vinyl to dampen sound. I avoided them because of the material and labor costs.
Posted by: bugleg at May 6, 2008 5:14 PM
Ibis, I've only used the 5/8" Quiet Rock and I'm new to using this product, but I must say it worked pretty well.
Posted by: Rick at May 6, 2008 5:16 PM
I did some early UL testing for quiet rock, and while I have never actually installed it in a house (we built frames to fit the rock, which makes things go a lot easier, no electrical cutouts, etc.), it seems like a real pain in the butt to install. It has a thin metal plate sandwiched in between layers that makes it real tough to cut. The manufacturer was saying to cut it with a circular saw and a plywood blade! It was also expensive at the time, $80 a sheet. I don't know if the price has gone down since its introduction, but between the price, and the installation headaches, I would want to be judicious in where I use it. But I guess ultimately it's no worse than green glue, and it did significantly decrease sound transmission when installed properly.
Posted by: guest at May 7, 2008 6:52 AM
6:52 - I don't know what Quietrock you tested, they have multiple kinds. But the ones that most people seem to be using (510, 516, 525) don't contain any metal, they are made of a layer of viscoelastic polymer between two layers of gypsum. I have not tried it yet, but according to their website, it is cut and installed the same way as regular drywall. It's slightly heavier than regular drywall, but the principle behind Quietrock is not an increased mass or a sheet of metal. The sound is absorbed by the viscoelastic material in the center. My understanding it that it's the same principle as using green glue between two sheets of regular drywall.
Posted by: Ibis at May 7, 2008 9:22 AM
If you travel to any drywall contractors forum, you can search for discussions about quiet rock installation. You will fing that none like the score and snap. Two sheets of standard drywall glued together (this is what quietrock is)will have a remaining paper layer in the center. You can't just break through this. Very misleading marketing.
Second, since we have identified that quietrock is simply two sheets of plain old drywall glued together, the question becomes "why can't I do this in the field?" And the fact is you can. Buy local drywall, apply glue. The cost is substantially lower to pay a contractor to do this in the field.
Third, applying in the field is not only substantially cheaper, it is also higher performance. And not by a small amount.
The quietrock is a great idea, but it is too expensive and low performance relative to asembling in the field.
Posted by: guest at May 7, 2008 10:13 AM
Ibis,
Green Glue and QuietRock are both viscoelastic systems, true enough. However the greenglue has 4 times the damping capacity over quietglue. Independent lab testing has demonstrated this on several occasions. This lab data is openly available online for all to see.
Posted by: guest at May 7, 2008 10:16 AM
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