QuietRock ES
| Posted in General Questions on
Hello Everyone! We are building a house in northern New Jersey and trying to enhance quiet and acoustics throughout the house while we have the chance.
I’ve looked at various general options for treating a whole house (instead of just, say, a home theater), and have zeroed in on a product called QuietRock ES. The material will be more expensive than 5/8 Type X drywall, but it offers materially improved sound isolation performance, and it looks like handling and installation are very similar to normal drywall.
I am thinking of using this product in a variety of strategic areas that would cover perhaps half of the drywall surfaces in the house. A regular drywall crew would do the installation, with some instructions from me. I would do the sealing of electrical boxes and seams myself.
A popular alternative with similar rated performance is to use multiple layers of drywall with Green Glue in between. But the Green Glue is very expensive, even in bulk. According to my math, doing a Green Glue assembly would save only about 10% in material cost, while adding the labor and complexity of spreading the glue and hanging secondary sheets.
Attached are the manufacturer’s performance claims for both QuietRock ES and Green Glue assemblies.
Here are some questions for the hive mind:
1 – Various posters on GBA have speculated that the QuietRock product is not vapor permeable due to its damping layer. But the manufacturer’s website states in various places, “Because QuietRock is a gypsum based product like standard gypsum panels, its water permeability properties would be the same as standard plain gypsum drywall. The visco-elastic polymer layer within the panel has no effect on water or moisture permeability.” Does anyone know of any reason to not believe this claim? We will have closed cell spray foam in many of our exterior walls, and I definitely do not want a problem.
2 – Does anyone have any other thoughts about the most economical ways to achieve a quiet house with good acoustics? Without hiring a sound expert and designing custom solutions for every dang space?
3 – Like many people, we have windows in our house. I understand that the windows will isolate sound much more poorly than the wall treatment. But I am wondering if the windows will totally eliminate the value of the wall treatments or simply reduce the performance somewhat? Our windows are new, high quality, double-pane, and mostly double-hung. They are not elite high performance specialty windows.
Thank you in advance!
Brian
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Replies
Here are the performance claims... For some reason the system did not let me attach them to the main post.
Too lazy to pull STC data, but I can say from anecdotal experience in a recent renovation that just using 5/8” drywall everywhere (interior walls, exterior walls, ceilings) makes a noticeable difference over 1/2”. There’s just not much mass in the 1/2” ultralight stuff (44lbs according to Google compared to 74lbs for typical sheets of 5/8”). As Ted White from http://www.soundproofingcompany.com told me, 5/8 “doesn’t cost much more and the drywall guys stop bitching after the first day.”
Also, like others on here are sure to do, I would challenge why you are using CCSF. There are almost always better options from a financial and sustainability perspective, and (again according to Ted White) the sound transmission of CCSF is pretty terrible.
Thanks. We are planning to use at least 5/8 Type X.
We are using spray foam because we have no other choice, due to decisions made by our original builder, and because certain locations demand it.
I am aware that spray foam may not be favorable for sound transmission, but at this point there is no practical alternative for air sealing the house. I imagine the air sealing aspect of the foam will be very positive. It's the coupling of the structure that is an issue. I do not think there is a solution to that problem.
There's a lot of expertise here about different insulation options--if you explain the problem you are trying to solve with it someone might have a better solution. If you do use it, you can specify and "HFO blowing agent" instead of HFC, to greatly reduce the climate impact you incur by using it, and get slightly better performance while you are at it.
As far as your question about the vapor permeability, I'm a little skeptical about their claims. I don't follow their logic that it must be the same as gypsum and the polymer doesn't do anything--unless the polymer is applied in a grid pattern rather than a continuous layer. I would be inclined to buy a sheet (or a smaller sample or ask for a scrap) and tear some apart to see what that layer really is, and maybe do a test such putting it over a bowl of water and seeing how long it takes for the water to evaporate, comparing with regular drywall.
That is an interesting idea for an experiment! I do find it hard to believe their claim is blatantly fraudulent -- they state it so clearly.
We will be using Demilec HFO, flash-and-batt. Some of our walls are 2x4, and some are 2x6, and new siding has already been installed, unfortunately. I do not see another way to achieve air-sealed, high-R walls at this point.
Got it and makes sense. Not sure what exactly the previous decisions/locations are that demand CCSF, but if the ship has not entirely sailed, here was a very labor-intensive but effective approach to air-sealing 2x4 bays in exterior walls, and using mineral wool batts which you could get in the Safe n Sound thicknesses for better noise control: https://www.greenbuildingadvisor.com/question/exterior-2x4-wall-in-zone-4c-just-add-batts-or-do-i-need-vapor-barrier-caulk-tape
To your point about whether the quietrock will allow vapor transmission, someone who understands wall assemblies better than I do can chime in, but if you have CCSF, I don’t think you care about the permeability of the drywall, right? The sheathing can’t dry inward anyway because of the CCSF, and whether the drywall is permeable or impermeable there’s essentially no way that moisture from warm inside air can get to the sheathing, again because of the CCSF.
Also, not sure what the source of noise you are trying to prevent from getting in the house is, but I have done the drywall hat channels + 2 sheets of 5/8” with green glue deal on one wall that had 2 heat pump outdoor units on the other side and it worked well. My contractor was pretty open to it and now my wife and I can sleep in that room, which was difficult before If your noise is point-source, maybe you could get away with that on the few nearest rooms? If the noise is a busy street, say, it might be tedious and expensive to do that for a whole side of the house!
The isolation layer is probably an open cell material, which would be vapor permeable. I see no reason to doubt the manufacturer's claims here, especially since they have specifically stated in writing that their product is vapor permeable.
Quietrock IS effective, but it is NOT cheap. I agree with the other poster that just going up to 5/8" drywall will make a difference in sound transmission, and it will give you straighter and more solid walls too. I ONLY use 5/8" drywall in my own home for these reasons. It's not even all that much more expensive compared with 1/2", not even a 10% premium, and the labor is essentially the same to install it.
You could try a double layer of 5/8" drywall without green glue on your exterior walls. The mass of the second sheet is where most of the extra sound blocking comes from anyway. Windows will NOT negate the sound proofing you're doing with the drywall, but they are weak spots. If you replace your windows, use laminated glass in one of the panes of the IGU for sound blocking, and if the two panes are different thickness that helps too (no common resonances between both panes that way).
As you go up from doubling up the drywall you get into all the fancy stuff like resilient channel and that's where costs start going up significantly.
BTW, spray foam is essentially wasted in walls due to thermal bridging of the studs. Closed cell spray foam, due to it's rigid structure, isn't great for sound blocking, either. Open cell would be better for sound blocking if you want to stick with spray foam. I'd use mineral wool batts myself. You do want higher density insulation here (mineral wool or high density fiberglass), not the normal lower density batts. The higher density helps with sound blocking.
Bill
Windows will be your weak point, going crazy on wall soundproofing won't be worth it.
I learned a bit of a lesson on this myself. Since I'm by a busy street, I built with combination of staggedred stud and double stud walls with 5/8" Type X inside and out. Even with triple pane windows with different thickness panes to increase STC, the weak point is the windows. All the sound comes through the windows. In retrospect, all the time and fussing around to build a high STC wall was wasted.
Your double pane windows are around STC 27. A standard 2x6 wall with batts is at STC 36, it is already WAY quieter than your windows. Going up to 5/8" Type X as others have suggested would be about all that is worth it unless you are willing to get better windows.