Potential studio - with construction problems

Hello all. I've been loitering around here for a while now researching, reading the FAQ and following lots of threads - it's fascinating stuff and I take my hat off to those of you that do this for a living and donate so much of your spare time to answering questions. I've learned a lot from other threads but felt it was time to start my own as my problem is slightly different. So here goes. The studio I work for is looking for new premises to rent. A few months ago we found somewhere promising: a nice studio space, purpose built back in the late 1980s which needed a fair bit of updating but seemed a solid. We all got pretty excited about it until I started to notice a lot of footfall noise from the offices upstairs. I've since done some investigating and found the construction to be less than ideal (details to follow). We also got a band in to play loud (max level 115dB) in order to check level of sound leakage? to the offices above. There was a lot! Walls and floor were vibrating and I took a maximum reading of 80dB. Here's a few details about the building: The studio is located on the ground floor of an old building, it consists of a Live Room and Control Room connected via a corridor with heavy/solid doors and seals. Dimensions: Live Room 10 x 8 metres, Height 3 metres to ceiling, 4 m to 1st floor Control Room 7 x 6, Height 3 metres Outer walls of existing old building - bricks single leaf. One single glazed window. Inner studio walls - built c1989 - concrete block single leaf - onto concrete floor slab, coupled with wall ties to external wall. Air cavity varies from 100mm to over 1000mm in places due to the shape of the original building. There is no insulation in the cavity. One glass brick window. Studio floor - laminate>concrete slab. First floor (offices above) - thin carpet>concrete slab>foam insulation>original wooden floor (boards and joists). Huge RSJ spanning width of Live Room supporting above floor built onto internal concrete block walls Live Room ceiling - Perforated hardboard finish<fibreglass insulation<Chipboard fixed to a wooden frame - suspended from the wooden floor joists above by 2x2 hangars. In the ceiling void there is a ventilation duct which runs up through the building and terminates in the roof. There is no HVAC unit just a duct into the void! The duct is insulated/damped internally. sorry my sketchup attempts just ended up looking like Salvador Dali paintings so I've attached some scans of the original draft plans, hope that's okay? As you can see there are lots of issues! I haven’t gone into too much detail about the Control Room. Similar issues apply but the live room is where most of the problems are. It’s a really cool space and we would love to make it work. We would be recording and mixing all sorts of music – acoustic and full on loud rock/metal so isolation needs to be good. So a few questions: If we insulate/add mass to the internal walls will this help reduce flanking effects. Will a room within a room work as we already have two leaf construction??? Is there anything we can do to make this a useable studio? What are our options? I should stress that we are not committed to taking this place, but the owner is keen for us to move in. If we do he will lay new flooring including acoustic underlay on the first floor, which should hopefully minimize the footfall problem, and will also consider any other works that may need to be carried out. I hope I’ve covered everything (I’ve certainly waffled on a lot!). I've tried to include as much detail as possible but I'm sure I'm forgetting something. Yours (with very little optimism but some hope) Stu

"Live Room ceiling - Perforated hardboard finish<fibreglass insulation<Chipboard fixed to a wooden frame - suspended from the wooden floor joists above by 2x2 hangars. " The impact noise from above has to do with, at least, this ceiling. We all understand that mass is the main requirement to isolate sound, in respect to that, this is not mass. So you would have to modify this area, since the fully decoupled environment demands consistent mass barriers as much as possible, with the least amount of mass being the weakest link. But if we can trust the floor plan and what you know about this building, the issues are still standing in the way. Like the interior wall assembly that is coupled to the exterior wall...it is a direct flanking path ("..concrete block single leaf - onto concrete floor slab, coupled with wall ties to external wall." ). To the prints, in all the places that should be decoupled, I see no decoupling. So this is a flanking path again. Mass law is a poor help mate when trying to overcome these types of issues. Since it requires a doubling of mass to get 4-6 dB of isolation, you would have to add mass consistent with the block wall assembly to get a meager 4-6 dB extra sound isolation. But to be fair I cannot read the writing on the prints, not that it matters at this point. An undertaking of this kind would require some visual insight into the existing block walls, to examine where they are bonded (flanking) to the structure and how or if this connection can be broken and what are the ramifications if it were to be modified. The coupling of the block to the exterior is a big issue...big, and would hardly be able to be modified at all short of removing the block wall completely or adding mass of sufficient quantities to overcome the flanking. Sheetrock isn't going to do it. The walls should still be giving a fair amount of isolation, the problem is/are, the ceiling is weak, the windows of the exterior are leaking sound back into the environment reducing your isolation and there is the potential for the doors to not be as well gasketed as they need to be in order to stop sound at that point. It is the classic case of poor windows, doors and ceilings :)

Hi Brien Thanks very much for your reply. Sorry for not responding sooner, I've been away with the family for the weekend (School holidays here).

The walls should still be giving a fair amount of isolation, the problem is/are, the ceiling is weak, the windows of the exterior are leaking sound back into the environment reducing your isolation and there is the potential for the doors to not be as well gasketed as they need to be in order to stop sound at that point. It is the classic case of poor windows, doors and ceilings :)

Surprisingly the doors have been quite well built; two solid core layers, two seals etc, not perfect but the least of our worries given the flanking problems. I'm not sure what can be done about the window/s. I can only see one which has the glass bricks in the internal wall. The others are all blocked up according to the building manager, but I'm going to check this out. I should say that despite it's construction, the isolation from the world outside of the original building seems pretty good, although my view of that might change if a band started playing in the neighbouring garden! The ceiling is indeed next door to useless, and is certainly one of the things we would need to tackle, but as you said the other issues remain even if this is dealt with. I've been wracking my brain trying to think of a way of decoupling the walls but short of removing them I can't see what we can do. It's not possible to cut the ties so that flanking path will remain whatever else we are able to do - to make matters worse the control room/live room wall is tied too!

in all the places that should be decoupled, I see no decoupling

Yeah, I don't think they could have made it more coupled if they'd tried! What do you think? Should we walk away now? Can we solve the many problems without expensive construction work?

"We also got a band in to play loud (max level 115dB) in order to check level of sound leakage? to the offices above. There was a lot! Walls and floor were vibrating and I took a maximum reading of 80dB." The walls are most likely doing some bit of good but the interior side, the ceiling, this is what you would have to focus on. Given the real estate, you could build more framed walls, but the air space would have to be much, much larger than is typical, and even the mass would have to be....it's gonna be a lot of work and money :) But the head room you have is promising, so there is always the chance of making an environment that would get you the isolation you require.

the interior side, the ceiling, this is what you would have to focus on.

To replace the ceiling with a properly built, fully decoupled one - spring hangers, large air space, 2 layers plasterboard, green glue, caulk, insulation etc. - sealing the wall/first floor joint with caulk (currently expanding foam), and filling the space between the first floor joists with insulation(?) would cost about £5,000 for the materials alone by my estimate. Not cheap but combined with better flooring upstairs, it would probably be workable for us. We'd build some drum/amp risers to help isolate them from the structure too. Also would I be right in thinking bass traps and other treatments will help in that respect? It seems that the RSJ isn't supported by the internal walls so that's one less issue to deal with. Should we try to insulate/damp the RSJ to minimise transfer into the outer walls? Is it even possible?

Given the real estate, you could build more framed walls, but the air space would have to be much, much larger than is typical, and even the mass would have to be....it's gonna be a lot of work and money :)

We have considered this, but it would be too much work/money. The owner would be better off spending the money converting the space into offices :( Once again thanks for your help. I'll keep you posted. Stu

Hello again The landlord has decided that the only solution he feels will provide us and our neighbours with the required isolation, and therefore the only one he is truly comfortable with, is a room within a room. He's in the process of getting estimates for the job.

Given the real estate, you could build more framed walls, but the air space would have to be much, much larger than is typical, and even the mass would have to be....it's gonna be a lot of work and money :)

I'm unsure on what design he is basing these estimates (I've yet to see any plans) so I was hoping to get some more advice. Should it be a two leaf or one leaf construction? How much air gap between the block walls and inner frame/walls do you think we'll need? You say larger than typical - is this to combat the effects the 3 or four leaf construction we would have created? Hope that makes sense. cheers Stu

"(I've yet to see any plans)" When we see those we can talk about this more....

Like Brien said: without seeing what you actually have, no-one can give you valid detailed advice, just very generic outlines.

Should it be a two leaf or one leaf construction? How much air gap between the block walls and inner frame/walls do you think we'll need?

Total of two leaves, only ever two leaves, never on, never three. If there is some major over-riding reason why you have to have 3 or 4 leaves in some places, then that can be compensated to a certain extent, but it is best to avoid that as much as possible.

he only one he is truly comfortable with, is a room within a room. He's in the process of getting estimates for the job.

He's probably right about the concept, but I sure hope he understands what that actually means, in terms of "2 leaf on only 2 leaf"! It's also hard to understand how he can be getting estimates without even knowing how much isolation you need, and therefore what the basic structure will be (how many layers on each leaf, gap between leaves, insulation fill, doors, windows, etc.) Until you have a number, in terms of decibels, of how much isolation is needed and at what frequencies it is needed, then it is impossible to determine any of the construction details, so how can he be getting a quote? :?: :shock: - Stuart -

Thanks Brien and Stuart

Like Brien said: without seeing what you actually have, no-one can give you valid detailed advice, just very generic outlines.

I realise I'm giving you very little to go on but I hope you'll humour me for a while longer, I promise if this goes any further I'll provide plans and details galore! One detail I can give you is that we need at least 60dB reduction. The landlord is looking for a ballpark figure so he can decide whether to keep the building as a studio space or convert it to offices and make more money. His builder is using a rough guide drawing provided by this company: Custom Audio Designs. Here's their website http://www.customaudiodesigns.co.uk/ Unfortunately all their technical documents are currently unavailable but I have the one he is using. It's a single leaf construction as follows: 100x50mm stud frames, isolated from floor, RW3 insulation in stud cavities, optional acoustic membrane fixed to studs, two layers of plasterboard caulked, staggered joints etc. Similar ceiling construction but with appropriate joists etc. A layer of insulation (they specify their own on the sketch but lets assume it's RW3) covering the existing internal walls. This will be built within the existing space which consists of: External brick walls - cavity - internal concrete block walls, coupled by wall ties. :roll: So far so good. My problem with this, which I may not have articulated clearly in my earlier post, is that as the existing walls are already two leaf won't building this new room within the room make the already poor isolation worse by creating a 3 leaf construction? As you said Stuart:

Total of two leaves, only ever two leaves, never on, never three. If there is some major over-riding reason why you have to have 3 or 4 leaves in some places, then that can be compensated to a certain extent, but it is best to avoid that as much as possible.

I suppose what I'm trying to ascertain is: is a room in a room a solution? I realise you can't get specific due to lack of details but at this stage I think even generic outlines will help. Thanks once again for your time it's really appreciated. Stu

"External brick walls - cavity - internal concrete block walls, coupled by wall ties. :roll: So far so good. " There are two issues with a coupled wall assembly, maybe three depending on who you are and what you have written. One is that while it exhibits a mass/air/mass resonance at the low frequency that might be expected from a true two leaf it is complicated by the bonding of the two wall assemblies, the number two, no pun intended none taken I am sure, is that the transmission path introduced by the flanking creates a path for vibration above the LF level to move either in or out of this room. There has been extensive research done on simple two leaf assemblies, and some work on coupled block wall assemblies, a little work on a true 3 leaf, which suggests reduced low frequency isolation and reduced high frequency isolation above, I can't recall, maybe 10kHz. But a true 3 leaf rarely exists, unless someone builds it :) The point is, in order to combat this there are few things you can do. One is that you have to get distance from the offending wall assembly...that means square footage real estate. The other is mass, and it always helps to know what the mass/air/mass resonance of the current wall assembly is, to understand what it is you are fighting, where the low frequency cut off is to attempt to create a barrier that will compensate for this deficiency of the existing assembly coupled with the distance you erect it at.

Thanks Brien Oh man, my brain hurts!

The point is, in order to combat this there are few things you can do. One is that you have to get distance from the offending wall assembly...that means square footage real estate. The other is mass, and it always helps to know what the mass/air/mass resonance of the current wall assembly is, to understand what it is you are fighting, where the low frequency cut off is to attempt to create a barrier that will compensate for this deficiency of the existing assembly coupled with the distance you erect it at.

Thankfully we haven't committed to this place yet we're all just trying to see if there is a viable solution. There is probably room enough to have a fairly large airgap between the framework and block walls but if it's too large it'll detract from what's good about the space. I'll try to work out the M-A-M resonance and proceed from there. Do you happen to have any links that will help me with this? cheers Stu