hello everyone. obvious newbie but i have been spying for some time so i think i know the questions i need answered. at present i have 6.5m x 3.3m concrete garage foundation sitting on sub grade. the found block is almost 30 cm deep. i intend to build a single room to mostly rehearse in. mostly punk. full band with acoustic drums, can peak when drunk and 'in the zone' at 110db or so (god bless loud drummers ) the law here stipulates 31db max at property edge. :cop:
so.. 80db transmission loss is the aim.
on to the question.
i have approx 70 sq m of patersons precon blocks, 7n, 100mm thick, density 1750kg.
would a double skin of these using matrix industries mb01 resilient masonry wall tie to decouple the two leafs (and relevent insulation)be enough to obtain 80db tl? this seems an obvious question but i cant find any actual figures and any threads on subject have no conclusions as yet with actual tl achieved.
would a double leaf of block be impossible to match with roofs and doors? (therefore overkill)
would an inner leaf of block make acoustic control within the space difficult?
would a single leaf with the inner room made of timber and gyproc be better?
budget is zero for build as all timber, block and gyproc has been saved from previous jobs and they are demolishing a school not far from here= free fire doors.
if i get the go ahead from any experts here i will start to build immediately and post up a full build diary
thanks in anticipation, hilly
concrete block for new build?
Originally posted at johnlsayers.com, topic 17230.
Hi Hilly, and welcome!!!
:shock: :!: :shock: :!: 80 dB is a TALL order! Most folks here are pretty happy with 50-something, really pleased if they hit 60, and ecstatically jumping-up-and-down-on-one-leg if they even approach 70. What you want to do is ten times harder than "ecstatically jumping-up-and-down-on-one-leg", a hundred times harder than "really pleased", and a thousand times harder than "pretty happy". dB is a logarithmic scale: to get 80 dB of isolation you really do need to stop one thousand times more energy than for 50 dB. One question here: that "31 dB at the property line" is A-weighted, slow response? I sure hope so. If it is C-weighted, you are probably out of luck, unless you have about a half million dollars to spare... The good news is that, assuming there is some decent distance between your studio and the property line, you'll get a bit of attenuation from the air itself, as well as the normal 3 dB reduction per distance doubling. If your studio is, say, 32 meters away from the boundary line, then you can count on about 15 dB of loss due to the distance, so you'd only need to hit a level of about 47 dB right outside your walls, implying a TL of "only" 63 dB from the structure itself, which is far more reasonable than 80! However, your level inside with acoustic drums and heavy bass is likely to be closer to 120 than to 110. Drums alone can put out 115 db, payed hard...110db or so (god bless loud drummers ) the law here stipulates 31db max at property edge. :cop: so.. 80db transmission loss is the aim.
BRN-217 deals with that. It doesn't specifically talk about your 100mm blocks, but it does talk about 90 and 140 mm blocks. The level they could get from a single leaf of 90mm blocks was STC-46. And of course, STC isn't even a useful measure for studios, since it doesn't deal with the most important part of the spectrum. But that's what BRN-217 gives, unfortunately. They very best they got was STC-59 for 190mm blocks plus a layer of 16mm drywall on studs. That still leaves you 20 dB short. IR-586 also deals with this, but for cavity block walls using 140mm and 190mm blocks plus drywall. The good news is that they tried one test case of 90mm blocks with a 115m air cavity, half filled with fiberglass insulation, and managed to get STC-77, which is pretty darn good but most likely not repeatable for your case, due to the mounting method they used. When they changed the mounting method to something a bit more usual, all they got was STC-62. Not trying to dishearten you: just telling you the way it is.but i cant find any actual figures and any threads on subject have no conclusions as yet with actual tl achieved.
Got any more info on those blocks? Are they solid or hollow? How much do they weigh? etc.of patersons precon blocks,
Why do you need the ties? Are they required by code? can you leave them out? While a two-leaf masonry wall MIGHT get you close to the level of isolation you need, there's a practical problem in building such a wall: how do you prevent mortar from oozing out the back of each joint into the cavity, and falling, to form bridges lower down? That's hard to do. Even one small mortar bridge would seriously damage your isolation. For the types of isolation level you are looking for, you cannot afford ANY flanking at all. In fact, you will probably have to build a separate foundation around your existing slab, with a small gap willed with isolation material, and build your outer leaf on that, with your inner leaf on the existing slab. I can't see you getting 80 dB TL with everything built on one slab.would a double skin of these using matrix industries mb01 resilient masonry wall tie to decouple the two leafs
Very likely, yes. To get the same level of 80 dB for windows, you'd need extremely thick heavy laminate glass on both sides, with excellent seals and a large air gap. The same applies to doors: they would have to be extremely massive with multiple high quality seals. The roof and ceiling would have to match the walls: you'd need the same surface density in each, plus the same air gap (or larger). Since you say your block are 1750 kg/m3, that means a single layer has a surface density of 175 kg/m3. You'd nee the same on your ceiling, so that implies about fifteen layers of ordinary drywall.... :shock: Yup, you'd need 15 layers of 5/8" drywall to get to 175 kg/m2.... Not sure how you'd managed that!!!! So yes, your weak points would be your doors, windows and ceiling. Hard to get that up to 80 dB of isolation. Not impossible, but hard and expensive.would a double leaf of block be impossible to match with roofs and doors?
No more difficult than an inner-leaf of drywall. Pretty much the same.would an inner leaf of block make acoustic control within the space difficult?
Better than what? Better for what? I guess you mean an outer leaf of 100mm blocks, plus an inner leaf of several layers of 5/8" drywall? If the air gap is large enough, that can also get high levels of isolation.would a single leaf with the inner room made of timber and gyproc be better?
:shock: :!: :lol: :roll: There's no such thing as a zero budget for a studio build! Sorry. Maybe you can get a large percentage of your materials for free, but there are some major items that you are not considering: HVAC, electrical, and windows for such a studio are going to cost several thousand dollars alone, without even considering things like permits, inspection fees, plans, etc. Then there's the small issue of labor: Are you a qualified architect, bricklayer, electrician, carpenter, and HVAC installer? If not, then you'll be paying others to do at least that work for you, if you hope to pass inspection. I'd suggest that you need to re-think your budget.budget is zero for build
I wouldn't advise that at all. You don't have a plan yet. No idea of how you are going to build this, no idea of dimensions, no idea of isolation, not HVAC plan, no electrical plan, no window plan, no door plan, no ceiling/roof plan, no room layout plan, no acoustic treatment plan, etc.. In short, you are not ready to start building yet. Months away, at best. Maybe that all sounds a bit harsh, but it is the bare truth. To be brutally honest, you don't even have the bare bones of a plan, so I can't see that you are anywhere near ready to start building yet. You don't even know for sure how much isolation you really need, nor do you have any idea of how to get it, or if it is even feasible! 80 dB of isolation is really hard to do, and really expensive. Having said all that, I'm aware of of one studio that actually managed to get 100 db of isolation. That one was designed by Eric Desart, and he invented some new techniques to do it. But the budget had a few more zeroes on the end than yours does: it ran to seven digits... :) - Stuart -if i get the go ahead from any experts here i will start to build immediately
thanks for a very swift reply stuart.
i read the spec sheets on concrete blocks as supplied by the national building control which was the same(i thought useless) stc ratings. also their approved construction method of stud frame and gyproc looked like the dreaded 3 leaf wall :blah:
the concrete blocks are 20 kg, dense and rated for load bearing(stairwells in flats etc)
a wall of this height built single leaf would always have strenghtening butts built in. twin leaf walls achieve the same strenghtening through being tied together. the acoustic ties qouted were from an australian acoustic construction specialist. as i could not find one closer and i may need those ties that shoots the zero budget out the water before the 'free' bit is done :(
i can garuantee there will be no flanking as i will take plenty of time laying each block. a separate foundation for the outer skin is not really a problem at this stage and would actually give me more interior space
there are no windows as i neither need nor want them
the roof is actually going to be lead lined on the outside, made up of overlapped offcuts of no smaller than 180 x 90 lead sheeting left over from porch installations etc but i have absolutely no data on transmission loss for this product. it is fairly dense though. this will be covered with roof felt or some such( so i dont come home to find the local tinkers taking my roof to the scrapyard)
for such a small, well insulated room, in scotland, neither heating nor cooling will be required (a small electric radiator for a short time in winter, an even smaller desk fan for our pathetic summer) hence an inlet near the ground level and a squirrel fan for extraction at the ceiling height should keep everybody breathing. some of the baffle designs on this forum will take care of that. :D
electric box is being installed in my house and trunked into the studio. my sister is a power engineer with the power supplier and is fully qualified to carry this out.
no windows/no window plan
doors and frames from local school, standard fire doors(one meter for disability access) one for inner leaf, one for outer.
no room layout or acoustic plan is true i figured that since it was blockwork the exterior would be squared anyway so the interior design would be secondary. i hoped this meant i could start throwing up walls :twisted:
if you cant find data make your own. :idea:
today im going to start on an exact scale replica of what im gonna build (1/6).
im going to measure the sound from my loudest boom box playing really loud dub, then im going to build a 1 x 0.5 x 0.9 twin leaf block wall round it, roof it and take new measurements from same distance. surely scale has no difference if wall thickness are equal.?
next post will contain pictures and hard data (whether its good or bad, proofs proof)
:) Actually, scale makes a HUGE difference! The equations for MSM, TL, etc all deal with actual full dimensions: meters, kilograms, etc., for a very simple reason: Sound waves have real wavelengths, not scale wavelengths. A 1/6 scale model will tell you NOTHING AT ALL about the frequencies that will be a problem in your actual construction. It will only tell you about the frequencies SIX TIMES HIGHER than those, which are not a problem anyway. You need to know how the construction will respond to frequencies in the range 20 Hz to 300 Hz, not 120 Hz to 1.8 kHz!!!! So don't waste your time: building that scale model is a useless exercise in futility. Sorry! Acoustics just isn't scalable like that. I think your time would be far better spent by building another type of model: Full-scale, in 3D, in SketchUp. Make it accurate and detailed, and post the file here, so we can take a look and help you figure out how to do this. Comments on your previous post:surely scale has no difference if wall thickness are equal.?
Great! According to the rule of thumb in IR-586 (did you read it?), that's about one quarter of what you need to get to the level you want...the concrete blocks are 20 kg, dense and rated for load bearing
You can lay them very carefully, but that still doesn't guarantee that nothing will leak out the back, into the cavity. In fact, if the mortar is not leaking out a bit anyway, then you aren't laying them right... So you need to invent some type of system for removing that mortar while you work, and preventing anything from falling into the cavity. Also, you need to plan how you are going to do that while at the same time also installing the ties, and at the same time also installing the insulation that has to go in the cavity. This is a big challenge, nowhere near as easy as you seem to think.i can garuantee there will be no flanking as i will take plenty of time laying each block.
Great! That takes one potential issue out of the equation. So your weak points will be only doors, ceiling, roof, HVAC and electrical.there are no windows as i neither need nor want them
Great! Lead is good. Lots of mass, little resonance. It's also about 12 to 16 times more dense than drywall, and at least 6 times the density of concrete, so a thin layer goes a looooong way. So, in order to match the mass (surface density) of your 90mm concrete blocks, you will only need lead plates about 15mm thick... The key point here will be how you seal those plates together. I guess good old-fashioned soldering with a blowtorch would be the best. So, at roughly 184 kg/m2, that lead on your your roof is going to weigh roughly 4,000 kilograms, plus the framing, plywood, tar paper, and final outer finish. I'm guessing you'll have maybe 6 or 7 metric tons or so up there. How do you plan to support that amount of mass? Did you do the math on that? What type of trusses do you need? What type of additional load does your local building code require you to factor in (required minimum live loads, dead loads, wind loads, snow loads, deflection, etc.)? Then you'll need something similar for the inner leaf: another 6 or 7 thousand kilos hanging from your ceiling joists. It looks like you'll need at least 2x12 rafters and joists to span those distances safely with that load, but you'll have to check with your structural engineer on that: don't take my word for it! It's just a guess, and I'm not structural engineer! You did hire a qualified structural engineer for this build, didn't you? If not, then you need one. You can't just go hanging ten thousand kilograms of lead, wood and drywall over your head, and hope it will be OK, without getting a properly qualified professional engineer to make sure.the roof is actually going to be lead lined on the outside,
Lead is the studio-builder's dream product! Very high density, and yet also somewhat limp. It has great characteristics for isolation. I was involved indirectly with a studio here in Santiago that installed heavy lead plates in the walls, as they were located in an ordinary office building and the only way to get the sound down to acceptable levels in the thickness of an ordinary wall, was with lead. It cost them a fortune, of course, but it worked. But their requirements were rather less than yours. They only needed 65 dB TL.but i have absolutely no data on transmission loss for this product.
IT sure is, which is what makes it so great for studios! Roughly 15 times more dense than drywall, 6 times more dense than concrete, 5 times more dense than granite, almost twice as dense as steel, and yet relatively soft, pliable, and with great resonant characteristics. If it wasn't for the price, we'd probably all build our studios from lead! It acts sort of like limp mass, too.it is fairly dense though.
Ummm... I beg to differ! Precisely BECAUSE it is a small room AND ALSO extremely well insulated, not to mention totally sealed hermetically air-tight (not once, but TWICE), it WILL need air conditioning. Unless you never ever plan to have people or equipment inside there... People have this strange habit: they need to breathe Breathing takes in air, removes the oxygen, adds carbon dioxide, a large dose of moisture, and several other unpleasant things. Those need to be dealt with. Equipment gives off heat, and so do people. Equipment and instruments need certain environmental conditions in order to work well. In a rather short period of time after you clso the door and start making music, the environmental conditions will be way out of whack, and so will you, your equipment, and your instruments. For example, most instruments need a fairly constant range of temperature and humidity in order to simply stay in tune! Equipment needs to be supplied with cool, dry, clean air. So do people. The only way you can do that is with an air conditioner. Get one: you will need it. It is a major mistake to think that just because you live in a cool climate you can get away without proper CONDITIONING of the air. Air conditioners don't just cool: they also dehumidify, filter, and move air. And no, trying to do the same with just ventilation will not work. Ventilation alone CANNOT reduce the humidity (especially in Scotland! Last time I was there, I see to remember noticing a lot of water, both on the ground and in the air...), and brings with it another series of issues, such as dust, uncontrolled temperature swings which will ruin the tuning of instruments, etc.for such a small, well insulated room, in scotland, neither heating nor cooling will be required
:lol: :!: :roll: :shot: Ummm.... I don't think so!(a small electric radiator for a short time in winter, an even smaller desk fan for our pathetic summer)
Same as above: I think you need to get yourself a good book on air quality and HVAC, and do some research on how temperature, humidity, and other atmospheric parameters have a huge effect on people, equipment and instruments.hence an inlet near the ground level and a squirrel fan for extraction at the ceiling height should keep everybody breathing. some of the baffle designs on this forum will take care of that. :D
Great! Tell here that you need full star grounding, a separate grounding grid, and neutral bridged to ground at the distribution panel in your studio. She'll understand what that implies.electric box is being installed in my house and trunked into the studio. my sister is a power engineer with the power supplier and is fully qualified to carry this out.
You did say that you want 80 dB TL, right? So what is your plan for adding some serious mass to those doors, hanging them, and putting the triple seals around the edges? A fire door is a good start, but only a small part of the entire issue. For 80 dB TL, you need extreme doors. I'd suggest a pair of Superdoors, at least, with a large gap between them.doors and frames from local school, standard fire doors(one meter for disability access) one for inner leaf, one for outer.
Square???? :shock: You never mentioned that it was going to be SQUARE!!!! That's the worst possible shape for a room, as all the modes will be on top of each other! Originally you said it was going to be "6.5m x 3.3m", so how did that suddenly turn into a square? Besides, you don't have to build lock walls square... You can angle them, curve them, stagger them, and splay them almost as easily as drywall. And "besides #2": Good acoustics will not happen on its own, just because you thought that square blockwork was good/bad! Good acoustics is the result of design, not chance. What ratio are you basing your design on? I'm assuming that it really is going to be 6.5 x 3.3, but you never mentioned the height, so it's impossible to say for sure what ratio you are intending. However, assuming normal ceiling heights, it sounds like you are aiming at a very old Volkmann ratio, not one of the better ones. Why is that? It fails two of the three critical tests used by the BBC for determining if a room is usable as a studio.no room layout or acoustic plan is true i figured that since it was blockwork the exterior would be squared anyway so the interior design would be secondary.
The intereior design is NEVER secondary for a studio! It is the number one, primary, initial, first and most important of ALL aspects! Everything else takes second place to the interior. It is, after all, what the sounds waves will see and interact with. It is what you will see and hear when you play inside the room. It is the entire purpose of why you are building in the first place: to have a room where your band can play, that doesn't sound like crap. And believe me, it will only "not sound like crap" if you specifically design it to "not sound like crap". If you let things happen by pure chance, with no attempt at design at all, then I can guarantees that in reality it WILL "sound like crap". Maybe you need to do spend a little time on thinking about and planning the interior, before you you decide where to put those walls and doors... - Stuart -... so the interior design would be secondary.
The data exists, if you cannot find it, we call that lazy.if you cant find data make your own.