Travels in Basement Selection - London, UK

Hey there, First post for me, though i've very much enjoyed reading the forum for some time and am pretty stunned by the level of expertise on show! I'm in the process of looking for a house to buy and wanted to ask a couple of directional questions to guide my search. My work is split between film and tv composition, playing in a band and recording myself and others in my current (pretty modest) home setup. My ultimate goal is to have a single space which can be used for all of the above. Ideally a control room/programming suite and a live room large enough to rehearse a 4 piece band. We're definitely at the louder end of the spectrum, pushing a lot of synths through PAs etc, so we're going to need to be at the extremes of soundproofing. When I've sketched out floorplans, I don't think this can work in a space much smaller than 40m2 though i might be wrong. The kind of townhouses i'm looking at in east london do often have these kind of size basements available, and with difficulty in getting planning permission for building at this scale in the garden or anywhere else, that basement is starting to look like the most realistic solution. Bearing in mind most of these houses are terraced so again it's maximally challenging in terms of isolation. My 2 main questions are these; 1. Is this a ridiculous idea? Am I missing something obvious? 2. As I'm looking at these basements, how much space should i be writing off for isolation etc. 0.5m on walls, ceiling etc? More perhaps? Is there a minimum ceiling height to make it workable? Any other characteristics that are showstoppers or of benefit? Any and all help/comments gratefully recieved! Thanks in advance. Daniel

Hi Daniel, and welcome to the forum! :) A basement is actually a really good place to build a studio generally, since that implies that the room is surrounded by earth on all sides, so isolation can be high. It also implies that the floor is a concrete slab resting on the ground too ("slab on grade"), which is excellent for a studio floor. So from that point of view, that's a good choice. The biggest issue with basements is usually ceiling height: Commonly, it is very low. Ideally, you want at least 8 feet (2.4m) of height in the finished control room (implying even more height to start with), and still more than that in the live room / rehearsal room: 10 feet (3m) is good, 12 (3.6m) is even better... Of course, that doesn't mean that it is impossible to have a studio with lower ceilings: just that it is not ideal. The lower it is, the worse it sounds, and the more treatment it needs, which makes it even lower still...

I don't think this can work in a space much smaller than 40m2 though i might be wrong.

That's probably a good estimation, but once again "more is better". EBU specs call for at least 30m2 of floor area for a control room, ITU says 20m2 to 60m2 for stereo, 30 to 70m2 for multichannel (5.1). Once again, that does NOT mean that you can't build a good studio with far less floor space: many forum members have built very successful rooms in smaller spaces: (one of my clients in Canada is just putting the finishing touches to his basement studio that I designed for him, in a total space of about 43m2, and he has four rooms: control room, live room, vocal booth and drum booth. The control room there is 14.1m2. So it can be done in small spaces, but then you do have to recognize the limitations you will have. The laws of physics are, unfortunately, immutable: Small rooms just do not react as well as large rooms, simply due to the relative size of the room as compared to the wavelengths of sound. So small rooms will have much more uneven bass response, and more problematic modal issues than large rooms. It's just the nature of the beast, and no amount of treatment can "fix" it. Having said that, small rooms can still be very usable: John has designed and built entire studios in a shipping container! So, as long as you are aware of the limitations, and can live with the results, then small rooms are usable. A couple of general "rules of thumb": The smaller it is, the more bass trapping it will need: The smaller it is, the more attention to detail it needs in the design stage. The smaller it is, the more attention to accuracy it needs in the construction stage. The smaller it is, the more complicated it will be to build. The smaller it is, the more expensive it will be per square meter. Etc.

1. Is this a ridiculous idea? Am I missing something obvious?

Not ridiculous at all! You aren't the first and wont be the last to build a great studio in a basement! The "things missing" are the same as are practically always missing in first time home studio concepts: HVAC, electrical, windows, doors. Those are the largest, most-forgotten aspects of studio design. HVAC is not a luxury for such a studio: it is a basic life-or-death need (very literally). Getting high levels of isolation at low cost implies that you need to build two entirely sealed, air-tight, hermetic "shells" around you: those are called the "outer leaf" and the "inner leaf", and each of them is an absolute barrier to air. But since you and your friends/clients probably do need to breathe every now and then while playing ( :) ) you do need a system for getting fresh air in, and stale air out. Doing that means that you have to chop huge holes in your perfect acoustic isolation walls, when in means that they are no longer isolating anything! So you need to build large, heavy "silencer boxes" at each point where an air duct goes through a wall. Those take up a lot of space, and generally that space isn't planned for to start with, so there's no place to put the life support system! HVAC is an integral part of any studio, and needs to be taken into account very seriously, right from the start. And it's not just fresh air /stale air: you also need some type of small air conditioner in each room (such as a "mini split" system) to keep the air cool and keep the humidity under control. So HVAC is a major "things missing" in most early studio designs. Next comes "electrical": Once again, you can't just punch holes in the wall every place you need an electrical outlet, switch or light fitting! That wall cost you major money to build, since it is an acoustic isolation shell, and even the tiniest hole will drastically kill the isolation. So you can allow yourself just one single hole to bring electrical power into each room, and even then that hole has to be very carefully done and sealed. From there, all of the electrical work needs to be distributed internally, with surface-mount outlets, switches and fixtures, and surface-mount conduit or ducts for the wiring. Finally, windows and doors: they are another compromise on isolation, and need extra care and attention to detail. Windows cannot open: they must be fixed, sealed in place. And thick. And heavy. Doors too must be even heavier, much thicker, and fitted with multiple seals around the entire perimeter. Here too there can be no holes that penetrate the door completely, so no normal latches: just handles, and automatic door closers to control the rate of closure, and keep them pushed up tight against their seals. One final item is structural: isolation requires mass, and lots of it. You will need a structural engineer to check what you are planning to do, to ensure that it does not overload the structural capacity of the building.

how much space should i be writing off for isolation etc. 0.5m on walls,

That depends on how much isolation you need. For higher levels of isolation, you need more massive walls (heavier) with larger air gaps between them. The absolute minimum workable air gap is about 10cm, plus the thickness of each leaf (probably about 3 cm), so its practically impossible to have a wall thinner than about 16 cm. For very high levels of isolation, you might need a 30cm air gap and 5cm on each leaf, so the each wall would be 40cm thick. Then you also need to allow for the acoustic treatment, in addition to the wall itself, to figure out how much usable space you will have to move around inside the room. The actual acoustic calculations are done with reference to the hard boundary surface of the room, but the treatment can be many cm thicker than that, poking out into the room area. That should get you on the right road, I hope! - Stuart -

Wow! Thank you so much for this - really appreciate you being generous with your time, this has given me a ton of perspective and a huge amount to think about! I pity the estate agents who will be trying to sell me houses! :) One final question. If I take the upper bound on isolation as your describe, say 40cm, do I need to account for this on the ceilings as well as on the walls? i.e. would a 3.4m high basement structure yield a 3.0m usable height in the room? If so, it seems that any basement with a ceiling height under 3m would be challenging. Thanks again! D

If I take the upper bound on isolation as your describe, say 40cm, do I need to account for this on the ceilings as well as on the walls? i.e. would a 3.4m high basement structure yield a 3.0m usable height in the room?

A room with a 3m ceiling would be really nice! But it's rather unlikely that you'll be able to find a basement like that. If you do, then as soon as you sign the lease, run right out and buy a few lottery tickets too, since your luck won't hold much longer! :) Seriously, to answer your question: Yes you should allow the same space on all sides, but with a caveat: If you can't get enough air gap, then you can compensate with more mass. It's the combination of "mass" plus "gap" that defines the lowest frequency that a wall/ceiling will isolate, and increasing either of those is good. So if the gap has to go down then the mass can go up. In other words, you can "beef up" the existing floor above your basement with more mass, either by putting a layer of something heavy on top (eg: thick plywood or OSB), or by doing it from underneath: cutting it into strips that fit between the joists. Of course, Murphy is not going to give up that easily in his attempt to thwart your efforts! There are also physical limits on how much more mass you can add, imposed by the structure itself: The joists above you can only support so much weight safely, so you need to get an expert (structural engineer) to take a look and tell you how much extra you can add safely. So even if you can only find a place with a 240cm ceiling, or even (gasp!) 220cm, it is still possible to get decent isolation out of that and to use it as a relatively good studio. It won't be quite as good as a place with 3m ceilings, but if that's all you can find, then that's what you'll have to live with. One "curve ball" for you: Some folks here on the forum have actually gone the other way: Ripping out their basement floors, digging down a few (dozen) centimeters, then pouring a new floor.... People have been known to go to extreme measures to get the best possible room. Of course, if you do that then you certainly need professional help (unless you are already a qualified structural engineer and a certificated building contractor!), not to mention deep pockets, but it might be an option worth considering if you can't find anything else. But hopefully it won't come to that: Hopefully you'll find something with nice 2.8m joists above, and 60m2 of space. - Stuart -