Two Car Garage - Heavy Band Rehearsal Room in Neighborhood | John Sayers’ Recording Studio Design Forum archive

Hi there "danexplodes", and Welcome! :) Congratulations on your new home! And also on having the space to build a studio!

and a wife that is less than thrilled with my undying love for loud music, heavy breakdowns and screaming.

OK, the "loud music" part I get, but the ... "breakdowns and screaming" part ??? ... ummm ... .well ... :shock: :!: :)

that will be well isolated from my back neighbor while they are within their home ... and my wife while she is within our home,

Isolating for your neighbor shouldn't be too much of a problem, due to the distance. At 100 feet away, you have the natural attenuation of air on your side, and also the spread of sound over distance. The biggest issue will be your wife, who is only a few feet away. Question: Is the garage physically connected to the house? Eg, do they share the same slab, or are they connected by a concrete pathway, covered way, etc? If they are fully detached, with nothing connecting them at all, then that's the best case.

There will be a drummer,

OK, take whatever budget you had in mind, and multiply by ten. :) :lol: :shot: Naah, not quite that bad: Drums are the hardest of all instruments to isolate, for two reasons: 2) they are the loudest of all, and 2) the produce a lot of low frequency energy, which is much harder to stop than mids and highs, is not directional, and tends to carry very well over long distances. So having a drum kit introduces an extra level of challenge.

playing mostly hardcore punk.

So take your newly updated budget, and multiply it by another ten! :) I's hazard a guess and say that you'll be getting upwards of 110 dB inside your studio, very likely upwards of 115, and possibly approaching 120. That's loud. And that's hard to stop. The question is: How quite does that have to be on the outside, to maintain matrimonial bliss? You'll need a sound level meter to answer that. And your wife. She'll have to tell you what she considers "acceptable".

The garage is constructed with 2x4 framing, 1/2' plywood sheathing, and a layer of stucco on the exterior.

That's a good start. How thick is the stucco? Also, what about the roof? How is that built? Also: windows, doors, electrical.... More info needed on those. Photos would be good!

I am familiar with the construction of room in room,

Excellent, since that's what you'll need here, without any doubt.

floating floors,

Absolutely not necessary here. It would be a waste of money, and there is no reason at all to even think of one: Contrary to popular belief, floating floors are almost never needed for studios.

MLV

You won't need any of that either. MLV is mass. Very EXPENSIVE mass. Sound waves react to the amount of mass they find in front of them, not to the price tag. The really don't care how much you paid for your mass, so it is logical to use the least expensive mass that will accomplish the job. That is usually plain old 5/8" fire-rated drywall, in most places around the world. MLV does have a very few uses in acoustic isolation and treatment, but it is for rather specialized situations, which does not seem to be the case at all with your build. The manufacturers of MLV have done a good job of hyping their product, and trying to convince the world that it is THE solution to ALL isolation problems, when in fact it isn't. I mean, it will work, for sure: there's no doubt about that, since it does have the needed mass. But a plain old sheet of drywall will work just as well (or even better) in the vast majority of cases, and will cost you much, much less. So if you value your money, and want to build this as inexpensively as possible, then stay away from MLV, except for the very few situations where it is needed.

I'm looking for some kind of guidance on what exactly I can do for the best reduction of sound in this scenario.

The more technically correct name for "room in a room" construction is "fully decoupled two-leaf MSM isolation system". MSM stands for Mass-Spring-Mass, based on the principle of physics that makes it work: you have two bunches of "mass" with an air "spring" between them. That is a tuned resonant system that will only oscillate and resonate at one specific frequency, while actively isolating all others. If you tune it correctly, it will isolate the entire audible spectrum. You tune your wall by selecting the correct mass for each of the two leaves, and the correct size of the air gap between them, and the correct type of damping inside the cavity. There are equations for calculating all of this, and also rules of thumb for estimating it, and also piles of laboratory test results from hundreds of different combinations of mass, spring and damping materials, if you prefer the empirical approach. The method you use for arriving at the type of construction you need is not really important, as all three of the above approaches will get you to the goal. But what IS important here, is to define that goal very well, so you know what you are aiming for. That goal needs to be expressed as "I need zz decibels of isolation" and also "the lowest frequency I need to isolate is yy Hz". Once you have those two parameters, the rest is easy.

I get framing material, rockwool insulation, plywood, and drywall through through my company.

Lucky you! Excuse me while I turn green with envy.... :) So your cost of materials should be very low, as compared to most home studio builds. Do you plan to do all the labor yourself as well, or will you hire a contractor?

I've also got a large stockpile of Green Glue, acoustic caulk and a roll of MLV left over from other jobs.

The GG and caulk is very, very necessary, and very useful. How much of each do you have? The MLV (as I mentioned above) is superfluous. Once again, use it if you want, since you already have it, but it isn't necessary. I'd suggest saving it for the "treatment" stage, after the room is built, since MLV can be used to make limp membrane traps, with some degree of success. How big is the roll you have?

So really, just the best suggestions for this project and I will worry about any additional costs later.

I'd start by defining your isolation goal, in terms of dB. Get out your sound level meter, play loud heavy punk music on a good set of full-range speakers set up in your garage, then while your wife has the meter in her hands, in the places she will normally be inside the house, slowly turn down the music until she says "That's fine". The level shown on the meter ("C" weighting, slow response) is your final goal for "How quiet I need to be.". Subtract that from the level measured in a typical jamming session, and the difference is how much isolation you need. Simple! With that number in hand, you can the calculate, estimate, or look up the set of construction materials, thicknesses, and techniques that you'll need to use to build your room. However, using the highly scientific "empirical estimation wild guesstimate" technique, I'd imagine that you'd be looking at probably beefing your existing outer-leaf walls and roof with more mass, sealing them air-tight with some of your caulk, then building your inner-leaf frame a couple of inches away from your outer-leaf (so you can get about a 10" air gap), filling the cavity completely with 50 kg/m3 mineral wool (or 30 kg/m3 fiberglass insulation), then using two layers of 5/8" fire-rated drywall for your inner-leaf mass, with three tubes per sheet of GG in between, sealed and caulked air-tight. That should give you about 60 dB of isolation, perhaps a bit more, which hopefully will meet the critical WAF test (WAF = "Wife Acceptance Factor). So your wild heavy punk sessions should be coming in at about 50-something dB right outside your walls, which should then be down to acceptable levels inside the house, where your wife will be. Of course, to get those levels, you still need to make sure that the doors, windows (if any), electrical and HVAC systems are all isolated to the same. So you'll need a pair of massively heavy back-to-back doors on the room, your electrical system will need to be the "single penetration plus surface-mount" philosophy, and your HVAC wil need silencer boxes and large ducts plus a very quite fan. If you do it all right, then you should indeed be able to get acceptable levels of isolation. - Stuart -