Requesting help w/ potential major cock-up w/ drywall weight

[Roflcopterrr]

Hello, I've built my drum room in my basement, with inside-out construction, and I thought it was all pretty much 'okay' until I actually read the labels on the drywall I used.

My heart sunk.

Ultralight.
Guess I should really have paid attention to the details.
So now I have two layers of drywall, equivalent to the mass of one sheet of 5:8.


I used ultralight drywall on virtually the entire thing, unknowingly. The framing is secured into the ground with ramset power-actuated nails, so I cannot take the framing down and re-drywall. I was considering adding the new layer to the existing outer drywall, but the clearances on two of the walls make this inaccessible. Would adding the proper drywall on the interior of the room create an unwanted 3rd leaf? Or is the space between the room and the foundation walls adequate that it doesn't become a problem? Thank you.

[Gregwor]

Bummer, but not the end of the world. What you can do is buy some heavy 5/8" drywall and cut it to size to slip pieces in between your studs. Use Green Glue between the existing ultralight and your new heavy 5/8". You just need to some little pieces of wood and screw them into the studs to hold your new drywall in place nice and tight. Seal around every joint with GG Sealant. Basically, it's the difficult way of beefing up your wall, but it works great. I had to do it with the rim board around the joists in my basement ceiling and it sure was a lot of work.

Greg

[Roflcopterrr]

Thanks for your reply - that's what I thought i'd have to do. Will using liquid nails around the perimeter of the beef-up pieces invalidate any benefits introduced by the GG? I'd be using the alternative quiet glue pro - GG is just too much.

[Soundman2020]

Will using liquid nails around the perimeter of the beef-up pieces invalidate any benefits introduced by the GG?

Firstly, why do you want to use liquid nails for that? Gluing layers of drywall together is a bad idea, and very likely is not even allowed by code. If you don't use GG for the beef-up, then don't use anything. As Greg said, just put the pieces in place, pressed up tight against the existing drywall, in between the studs, seal around the edges with acoustic caulk, then hold it in place permanently with small cleats nailed sideways into the studs. That will keep it in direct contact with the existing drywall, and will also ensure a good air-tight seal.


- Stuart -

[Roflcopterrr]

OK, ill bite the bullet and get GG.

[Soundman2020]

OK, ill bite the bullet and get GG.

If you can't afford it, then that's OK! You don't need it, unless you are aiming for really high isolation down to very low frequencies. If you proceed as Greg and I have outlined, and you only need moderator to high isolation, then you should be fine.

What is your goal for isolation? How many decibels of isolation are you shooting for? And down to what frequency?


- Stuart -

[Roflcopterrr]

OK, ill bite the bullet and get GG.

If you can't afford it, then that's OK! You don't need it, unless you are aiming for really high isolation down to very low frequencies. If you proceed as Greg and I have outlined, and you only need moderator to high isolation, then you should be fine.

What is your goal for isolation? How many decibels of isolation are you shooting for? And down to what frequency?


- Stuart -

My goal is to reduce the low-end thud heard on the second floor of the home. At this point, the drums are nearly silent from my second floor bedroom, except for the kick. The thud is virtually imperceptible, but unfortunately, the person I am trying to avoid disturbing works overnights, so they’re asleep all day. Their apartment is on the other side of the second floor, even further from the sound source than I am. I live on a very busy road, which happens to be quite a steep hill, so cars and trucks are constantly accelerating up and ambient noise is quite high all day, so... I should be comfortable with the amount of noise that has been stopped, but the kick thud is still there, and if you try and listen for it, you’ll hear it.

GG seems to be quite effective at reducing those lower frequencies, so if that and 5/8 drywall between the studs is what I have to do, then I’ll do it.

[Soundman2020]

Makes sense!


- Stuart -

[Roflcopterrr]

Just ordered a case of GG. Turns out that it's manufactured 30 minutes from my home, at Saint-Gobain in Granville NY. They've actually been in the local news for a good amount of time. I had no clue they made GG. Too bad they still made me go through a distributor, lol. Hoping for 8-10db improvement with the addition of the 5/8 and gg - is that unreasonable? If I can tackle the 'coincidence dip' then I think I will have mostly solved the still-slightly-persisting low end thump. I'll also be beefing up my door as well, just so there are no weak points. Currently it's a standard solid-core door. I was thinking one or two layers of 5/8ths on top of that.

I've tried recording dB measurements from the 2nd floor with a fairly neutral large-diaphragm condenser - a cad m179. Ambient noise averages at about 60db, as the road I live on (steep hill) is one of the only routes to a large community college, reaching 63-67 dB when louder vehicles drive up my road (during the summer I'm sure it hits 100+ - harley davidsons are loud uphill, especially when people modify them to be even louder .) During the rare moments that the road is quiet, it can drop to 55 or so. The drums played during that quiet moment seem to only affect dB by 1 or 2 points.

I am still SO bummed out about the drywall mix-up. I know it's a tiny room, and people have certainly had to tear down and re-do worse, but as a full-time student who also works full-time, time is precious right now. sigh.. just gotta deal with it.

[Soundman2020]

Hoping for 8-10db improvement with the addition of the 5/8 and gg - is that unreasonable?

That's reasonable, yes, but at the high end margin of "reasonable"? And of course, it all depends on how well you do the rest of the studio...

If I can tackle the 'coincidence dip' then I think I will have mostly solved the still-slightly-persisting low end thump

The coincidence dip is not in the low end. It's usually in the upper mid range, or even the lower part of the high end. And it's usually not that important, unless you are aiming for veyr high levels of isolation. If the low end is well isolated, the the mids and highs will be VERY will isolated.

I've tried recording dB measurements from the 2nd floor with a fairly neutral large-diaphragm condenser - a cad m179.

Connected to what? The CAD M179 is a microphone, not a sound level meter. What did you connect that mic to, and how did you calibrate it?

Ambient noise averages at about 60db,

Is that dBC or dBA? Did you set the meter to "fast" or "slow" response?

During the rare moments that the road is quiet, it can drop to 55 or so. The drums played during that quiet moment seem to only affect dB by 1 or 2 points.

That's VERY strange! Drums can easily put out around 110 - 115 dBC. So it would be VERY curious if you only saw them at 57 dBC when you are seeing traffic ten times louder than that, at 67 dB! Something strange is going on with your measurement setup or technique.

- Stuart -