Green Glue Application

[Anthony]

Well, I finally decided to order a bunch of green glue to isolate the wall between me and my noisy neighbor. The alarm clock of Death Metal every morning at 6:30 really iced it.

My wife commented last week: "He seems to be much quieter now, maybe he got the hint." To which I replied, "Honey, he's be gone for a week on a business trip."

Ah, townhouse living.

Anyway, I am ordering 12 tubes from bpape (you've got mail) and we'll probably end up starting this in a couple of weeks.

Some preliminary questions:
1) 1/2" or 5/8" drywall? The current construction is two layers of 5/8" firewall drywall on my side and presumably the same on my neighbors. I know I have the double layer because we measured it once when putting the theater in the basement. Whether or not my neighbor has the same is unknown.

5/8" would obviously be heavier, but also would end up having the same resonance as the layers underneath it. 1/2" would be lighter, but would spread out the resonances.

2) Green glue application: I see demo pictures of a random pattern, applied pretty thoroughly. Would there be any advantage of using a brayer (glue/ink spreader) to get a consistent thin layer on the whole panel, or is it better to have separate beads randomly all over the place? I can see the advantages both ways.

3) If I can get paperless drywall, would that have any effect?

Thanks in advance! We may be able to actually sleep in soon!

[bpape]

Hi Anthony.

I'd do the 5/8 anyway. The 2 layers below will act as one if the glued it together so they'll have a different resonance anyway. Realistically, the difference between 1/2 and 5/8 for any resonance issues is far outweighed by the additional mass.

Just drizzle it as they show. It will spread out on it's own. Trust me, they tried it a bunch of different ways during testing and this is what Audio Alloy recommends.

Also remember that this may not be a full solution for your issues. There are other places where sound is leaking I'm sure. Think about doing your outlet boxes in putty before you do the new drywall too for example. Also, the Green Glue takes almost a full 30 days to really cure and become it's most effective.

Bryan

[Anthony]

It's on a firewall, so no outlet boxes to worry about. The wall is just one big pure sheet.

And I understand the cure time aspect, so not to worry. Would it be better NOT to paint for a week or two to allow faster curing? I imagine priming and painting would inhibit any sort of air flow/diffusion to aid the curing process.

Thanks for the help.

Anthony

[MatrixDweller]

You might want to check out the lower level where the joists meet the floor above it. There is probably one area that is defeating the soundproofing the existing firewall should be providing. You could assume that if you have double 5/8ths drywall that your neighbor would also. The shared wall would also be a double wall if built to code. The STC rating is probably pretty high on that shared wall and adding another layer of drywall is not going to do too much more than what the existing wall is already doing unless there is a flaw in its construction.

If this is an upper floor thing, then it could be the attic that's the problem. I lived in a townhouse at one point and was shocked to find out that the entire attic was shared without any dividers. Pretty crazy I know, but seeing it was quite the wake up call to move out. That wouldn't pass building codes these days. There is supposed to be a 2-hour fire rated barrier all the way up to the roof. Even if your place is not in that extreme there could be gaps and minimal separation between you and the neighbors from the attic.

I'd confront your neighbor the next time it happens (or call the super or cops if it's at 6:30 in the morning). Or do the same to him at 4:00 in the morning (put the sub right up against the shared wall in a corner).

[Anthony]

I know the attic is separated. Don't know if the sound is coming through the floor. Next time I hear it, I will feel the floor and see if it's vibrating as much as the wall.

You can definitely feel the wall vibrating,though. So i'm pretty sure this Green Glue stuff will help.

We're pretty non-confrontational -- if this fixes it all,then great. However, if the problem persists, I may have to mount a transducer on his wall and send him subliminal messages

[Anthony]

Okay, well the 5/8" rock went up with the green glue (2 tubes per 4x8 sheet). So far the results are mixed, but it's only been 2 full days and nothing's been taped yet.

Voices and music are greatly attenuated. However, bass is not. There's a range between 60 and 500 hz that seems to still get through pretty loud. Again, only a few days have passed. We decided not to blow through the insulation for a couple of reasons: one, the paper stuff is completely dry and I read about major settling problems (the wet stuff cures and is much better but that's for new construction). We also did not want to fiddle with fiberglass there.

Will the taping and mud help things? At what point will we know if the green glue helped? Thankfully he obliges us by being noisy all the time so I'll know when it starts taking effect (grand theft auto part last night at 2 am -- closest we came to calling the cops, but miraculously we fell asleep).

Also, if there is transmission through the floor or ceiling, what can be done about it? We're getting new carpeting, so I will have access to the subfloor for a while.

Thanks.

[bpape]

The Green Glue takes a full month to really fully cure. Deep deep bass is going to continue to be an issue until the walls are insulated - sorry. What you have is an undamped drum. You just damped one of the heads but the other side and the cavity is still resonating freely.

Bryan

[Anthony]

Hmmm, well, we haven't painted or taped yet, so if I was going to insulate anyway I still can. Plus I have a ton of extra 5/8 drywall (I had to buy a full sheet to use 3"x 48" in one part).

Since I only have 6 stud bays to fill, I may just do it by hand.

Any thoughts on fiberglass versus cellulose?

[Anthony]

Well, this is as they say, where the plot thickens.

So now I'm thinking I need to add insulation, so I drill a hole 2" diameter with a hole saw to see what's what, where fireblocking is, etc.

Turns out, there's already insulation in the wall. It looks like 2" to 3" thick bats attached to the far (neighbors) studs, with a 3" air gap until my drywall. Edit: upon further reflection, it looks like they put bats designed for 2x4 cavities inside a 2x6 wall -- that explains the amount of fiberglass and air gap). So now I'm thinking I can't blow insulation in, but there's obviously some damping in there.

Ugh, now where to look? I do appreciate all the help.

I'm finding this a great exercise. We're not going to be in this house forever and our next house is either going to be new construction or a renovation job -- so best to learn on the starter house.