Advice needed new warehouse space

After running low ceiling studios for a number of years I am determined to go for something with more height. I am based in London. It is very hard to find any commercial buildings with good ceiling heights in central areas. Therefore I have been looking at Light Industrial Units - aprox 1200sqft in designated industrial areas. I have found what I think is particularly good one and I would like some feedback. Construction details 8.5m wide x 12m long. The building is pretty new - and very well built. No obvious flaws or gaps in materials. Mezzanine I will take down to leave blank space - that is apart from the sink and hot water facilities at the rear wall. The two side walls and the front wall with the entrance door are painted concrete slabs 200mm. The rear wall which seems to be steel cladding although I could not get round the back to check. But I assume it is the same as the front of the building of which I have attatched a photo. The ceiling is steel cladding as well with transparent plastic/perspex skylight I presume although I could not get close to it. It is 4m at the far wall rising to over 5m. There is a huge steel RSJ supporting it. Poored concrete floor. For an industrial building complex the neighbours are super quiet. Digital printers on one side and an office/storage on the other. I did not have a DB meter with me but it would seem a very quiet office environment - and the landlord wants it kept that way. So I have to be very sure of the soundproofing. Typically I will be recording bands - mostly rock so levels of 110db or more should be expected. I guess what I really need to know is will the existing structure provide (or could be modified to provide) a good outer shell in a MSM system? For me the steel clad ceiling is an unknown quantity - how would it behave? Does it have enough mass or would it need to be beefed up? Maybe a further outer shell ceiling built beneath it - or would this create a problematic 3 leaf system? Or is this good to go - fix some 100mm rockwool in between the ceiling joists? The front door with the window above it looks like another weak point. The door is fairly lightweight and the window is standard gauge glass. Would it be better to box these in with a further door entrance (another potential 3 leaf?) - or beef these features up somehow. Sorry for not showing any pictures of a design but basically I am viewing properties to decide on the best space to use before I design the rooms. But I want to have a fairly large live room, medium control room and another smaller room that can feature a small kitchen station, storage and function potentially as another iso booth. So each room would have its own stud framework and separate ceiling not attached to any other - as in a typical MSM 2 leaf system. The ceiling span for the live room would be 8.5m which I was going to brace in the centre with a suitable RSJ steel beam - mounted into the floor on separate columns. I have read alot on this forum over the last few weeks but could not find specific answers to these problems. I would appreciate if you can shed some light.

Nobody out there have experience of buildings like these?

hello - is there anyone out there??

"I guess what I really need to know is will the existing structure provide (or could be modified to provide) a good outer shell in a MSM system?" If it is concrete, then it can be used in the m/s/m build. Problem is, that in order for a m/s/m to function properly it has to be sealed pretty much everywhere. So I ask you to look into your structure, build the rooms in your mind and then suppose where the leaks are. And then draw it up on paper or sketchup...either one or both. The leaks come in the form of where the walls are :) OR are not. So you have a solid exterior with a poor roof that leaks...right? You would have to construct either something of a build that is low enough/far enough away from the flimsy roofing that still substitutes as a m/s/m, with the benefit of distance being your friend in respect to this roofing, which is flimsy, especially at the light panels. Overhead aircrafts present a problem? You have to consider that...

So on further discussions with the landlord who bought the building 10 years after it was built - there is no available information on how the ceiling is constructed. So when dealing with these kind of ceilings would it be advisable to build another ceiling below this as the "outer leaf" which is fully sealed against the "outer leaf" walls? Or could this 3 leaf system present major problems? Could the third leaf, the ceiling which is common to the neighbouring units, vibrate strongly at low frequencies? What is the worst case scenario with this 3 leaf construction? I do realise that this is a discussion on unknown quantities which is not ideal - I am just wondering what would be the most prudent course of action in these situations? The answer will probably be "find another building" - which would be a damn shame because in all other aspects the building would appear perfect. There are plenty of rooms to let with sealed concrete ceilings in London - but always have the standard range of ceiling heights - say 2-3m. I am determined not to be limited to these ceiling heights.

With a huge unknown like that, a three-leaf ceiling is probably a real option. But another option would be to hire an engineer who specializes in roofing to do a detailed survey of what is up there, how it is built, what MUST be done to it, what CAN be done to it, measure, analyze, etc. You'd probably need to do that anyway, to see what kind of shape the roof is in weather-wise, since no matter which route you take, the underside of that existing roof is going to be totally inaccessible once your build id finished. It will behind at least two full hermetic seals, so if there are any water leaks up there, you'd never know until it was too late. There would be no little drips to hint at problems early on. They would all be contained behind your multiple seals. So it would all be hidden, until one day... :!: So getting a professional checkup on that roof is probably a good idea anyway, and that will tell you a lot about your options for using it as the outer leaf in an MSM system. But assuming you do have to go with a 3-leaf: that's not the end of the world. There are ways you can compensate for the lost low-frequency isolation of a 3-leaf system: put more mass on the leaves (especially the middle one), and leave larger air gaps between at least two of the leaves. The basic objective of MSM is to get a resonant frequency that is low enough, where "low enough" means not more than half of the lowest frequency that you need to isolate. If you want to isolate the full spectrum, that implies a resonant frequency not higher than 10Hz. That can be attained, even in 3-leaf construction. It's just a bit harder to do, since there are TWO fundamentals for a 3-leaf, instead of just the single one for a 2-leaf, and both of those are higher than the for the 2-leaf. But more mass and larger air gaps make it feasible. In other words, 3-leaf is an option, especially in your case where you do have enough height to do it without bringing your final inner-leaf down so low as to make an unusable studio (which is the number 1 reason you want this place anyway! :) ).

Could the third leaf, the ceiling which is common to the neighbouring units, vibrate strongly at low frequencies?

Yes it could, theoretically. That's why it would be good to know how it is built, particularly with an accurate estimate of the surface density (mass per square meter), which is the basic factor for figuring resonance and isolation, and how it will react as part of a 3-leaf system, or even better, as part of a 2-leaf system. It would also tell you if you need to add some form of damping to the roof itself. But I'm a bit confused: I thought this was an isolated, stand-alone building that you will be renting entirely for you? What part of it will be "common to the neighbouring units"? IF the roof is in common, then so are some walls, and also the floor! You didn't make it clear that you'd be sharing part of this building with someone else.

The answer will probably be "find another building" - which would be a damn shame because in all other aspects the building would appear perfect.

I don't think the answer needs to be that drastic! :) I think the answer needs to be: invest a little money with a professional expert in roofing and structures, to find out what you really have, what state it is in, and what your options are. I don't think you need to abandon the entire building just because there is uncertainty about the roof! Rather, try to resolve the uncertainty. Sure, that will cost a bot of money, but it will be a tiny fraction of what the design and build is going to cost you anyway, and it will be money well spent. Bottom line? If this is the best building you have found, the location is right, the price is right, the size is right, and the only issue is doubts about the roof, then clarify those doubts and decide how to proceed based on that. Worst case? It turns out you need to replace the entire roof: more money, but otherwise you have a great building. Best case? The roof is perfect as-is, and you don't need to do anything: less money, and otherwise you have a great building. Most likely case? You need to invest a bit in fixing the roof and getting it to the stage where it can be a happy member of a 2-leaf or 3-leaf system: some money, and otherwise you have a great building. Sounds like a good outcome, all 3 ways, to me! :) - Stuart -

I do not subscribe to the three leaf as being such a detrimental effect in many cases, so I can not agree with what Stuart is saying, in respect to a 3 leaf :). My opinion is that no matter what you do, if you attempt a room in room build, this flimsy existing skin that is a shield from the rain does not enter the equation in respect to being a leaf. We assume the roof is flimsy, we target the TL, and build the mass/spring/mass assembly accordingly. Simple as that. There is a rat running wild on the Internet about this three leaf and the detrimental effect, and often the information >given< and the information received do not match. To be fair, what ever you are going to attempt to construct will be free standing, will not involve this overhead thin skin...and should not be constituted as a leaf....since your interior leaves will be thicker/denser than this shield against the rain and the air pocket will most likely be breached in many an area, as it were.

On the other hand, if you understand the equations and do the math, the 3-leaf effect is very real... - Stuart -

I understand everything...and this person does not have this issue, presently.