Maximising height of studio under garage.

I’m new to this folks, so forgive me if I am giving you more or less than you need. I'm hoping to build a facility at home for my 20-year-old son. He's studying music production and is also a songwriter and performer in a rock band. So the studio will ideally have two purposes: as a recording and mixing facility and also as a rehearsal venue for his (loud) band. If the room won’t serve both purposes, the key objective is to have a home recording facility. Based upon everything I've read here so far, I believe we'll need to build a "room in room" solution. Our chosen spot has some complications that makes it a bit hard to simply adapt the plans on your site, hence some questions. Here's the story. We live in an apartment block. There is a storage room under a shared garage that we wish to convert. On top of the garage is someone else's apartment - it's the only one physically connected to the garage. The owner is a light sleeper and won't appreciate any intrusion, no matter how musical. The floor and ceiling of the storeroom are made of reinforced concrete about 180mm thick. There is nothing but void and loose fill under the room. The walls are double block and brick (bricks are on the inside). The room’s dimensions are 6.85m long, 4.07m wide and 2.2m high. The floor has been covered with a material made from recycled car tyres – like the stuff they use in playgrounds – and is about 15mm thick. My main concern is the height restriction. If I follow the plans I’ve seen for a room-in-room construction, it looks like we will lose 200mm and end up with a 2 metre ceiling height. So my questions are: Do you think we would be able to use timber of a different dimension to maximise the height? Is there another lateral solution for this issue? Could the existing rubber flooring be a useful substitute for neoprene under the floor timbers or are we likely to get a lesser result this way? Sorry this has turned out to be a long question…but you did ask for detail!

Losing 20cm sounds about right, and you can probably reduce that a bit, but it's not just a mater of timber dimensions: it's a mater of the dimensions that you need in the air gap in order for it to be effective. The air gap is part of a tuned system, and the smaller you make it, the worse it gets. The smaller the air gap, the less isolation you have, and the higher the resonant frequency of the MSM system. You need a large air gap to help get the resonant frequency down lower, to give you more space for damping (minerla wool or fiberglass insulation), and better isolation. The air gap needs to be a minimum of about 10 cm in order to get decent conditions, but then you have to account for the thickness of the drywall that you are going to hang underneath that air gap: two layers of 15mm drywall is, of course, another 3 cm, so you really need to lose a total of at least 13 cm of height for reasonable isolation, and around 15 cm if you go with 3 layers of drywall (you say that your son is loud and the guy above is a light sleeper, so maybe 2 layers of drywall isn't enough: you might need 3). Adding more layers of drywall would allow you to reduce the gap a bit, and sure, you can play around with the math (see Eric Desart's charts for that) and use a smaller air gap with even more layers of drywall, but it becomes a war of diminishing returns very quickly: you get the stage where you cannot find joists that are thin enough for what you want and also strong enough to support the huge mass you now have hanging up there. You just can't get a good MSM system much thinner than about 15 cm. I guess you could use some exotic extreme mass substitute for drywall, such as lead sheeting, hung from steel joists instead of wood (for less depth), but the cost would be astronomic, and all you'd gain is a few mm. You might, possibly, get it down to around 10 cm, but the question would be: is it worth it? High expense for just a few cm gain in height? A 2.1m ceiling isn't really much better than a 2.0m ceiling, either aesthetically or acoustically. ( I guess you already know that a low ceiling isn't good for acoustics: If you plan to record in there, it will be hard to get recordings that sound open, clear and airy, due to the height. ) So the way I see it, you are pretty much stuck with the height limitation. Sorry to not be bringing you good news, but there isn't much to bring! The laws of physics (acoustics) are not on your side here. - Stuart -

Thanks for the advice Stuart. I suspect we should go with plan b and look at another site. We had been considering converting a commercial space (that we can pick up cheaply) that has no space restrictions. One last question though. We had planned to build a couple of sound booths in the studio - at least one of which could double as a vocal booth. The idea was to use these to record guitar amplifiers in a more controlled environment and build greater noise isolation from the outside world at the same time. It's a technique my son has used in professional studios. Clearly our booths would have the same height restrictions as the rest of the room, so maybe this won't help in terms of our acoustic issues. I just thought I'd check before we kiss the notion goodbye.

Funnel wrote:

IOn top of the garage is someone else's apartment. The owner is a light sleeper and won't appreciate any intrusion, no matter how musical.

That would be a deal-breaker for me.

Maybe you could buy the apartment above, where the light sleeper is, evict him, then knock out his floor / your ceiling, and solve all your problems at once? :) - Stuart - (Sorry bout that! ... I go a bit crazy late at night, and come up with these wild, impractical ideas. Must be the moon or something.... :) )

Stuart I think you're onto something here. With all the racket under his joint, the neighbour is bound to sell at a favourable price. And if that son of mine could write just one hit song maybe we could afford it. In the meantime, I think I'm off to check out warehouses. Thanks for all your time on this. Go get some sleep.