Maximum Sound Proofing For Residential Room.

G'day, I have a 10M x 6M space to build a studio, and just under $90,000 to spend on it. When I woke from my dream I was SO DISAPPOINTED!!! :( Actually, it's a proposed 4.6x3.5M room as part of our house extension, (see attached floor plan). The ceiling height should be the same as existing house, ie, 2.7M. My Goal For This Room: To teach drums, to play drums, to occasionally rehearse a band, (acoustic folk/rock band), and to record- mainly acoustic instruments. Loudness: I guess the loudest volume would be when we occasionally rehearse a full band. Otherwise, it would just be playing/teaching drums, (not metal or anything like that). The neighbours are set back a good way from the boundary that the noise shouldn't be a problem, and they seem understanding of what I'm doing so far. External Walls The proposed external walls, (150mm from boundary fence) would be 70mm Hebel aerated concrete panels, screwed to timber frame and rendered finish. Budget: The room is part of the whole house budget, so hard to give this. I guess on top of the standard construction cost, I would like to keep the acoustic construction element of it under $5000. Questions: As you can see from the drawing, the master bedroom is next door! (no other option in design). Therefore, my main concern is keeping the sound from the rest of the house, as opposed to outside noise coming in. 1/ Foundation: Will a concrete slab, (as opposed to stumps/bearers/joists) be a better option? 2/ Floor: What would be the best floor construction? I've heard differing opinions on whether or not to float the floor. My idea was to build the room on concrete slab, but have a wooden floor (smooth surface for recording acoustic guitar & vocals). Then for drums, have a standard rug or proper drum rug if they exist? 3/ Walls: What would be the best wall construction for my scenario? 4/ Ceiling: Best ceiling construction for my scenario? 5/ Insulation Material: Best stuff to put in the wall cavity? 6/ Window: Should the external window be acoustically designed, or would it not make that much difference? 7/ Door: Will the double door lock out more sound? I'm thankful for this forum - so comprehensive. I hope I have given the right information for you to advise. Please let me know if I haven't. Cheers, Jason.

Hi Jason, and welcome to the madhouse... err... sorry, I mean the forum! :) I wish I had "dreams" like yours! Mine mostly involve angry calls from the bank manager... :) Still, 4.6M x 3.5M x 2.7M is not too shabby. Certainly usable.

I guess the loudest volume would be when we occasionally rehearse a full band.

That implies upwards of 110 dB, probably 115, perhaps approaching 120. Id would be good if you take measurements with a sound level meter, to put real numbers on that.

The neighbours are set back a good way from the boundary that the noise shouldn't be a problem, and they seem understanding of what I'm doing so far.

Your CURRENT neighbours might be fine with the noise, but the NEXT ones might not... :) There are certainly legal limits that you need to meet, so call your local municipality and get a copy of the nose regulations. Then you'll have two objective decibel numbers: the "how loud you are" measured with the meter, and the "how quiet you need to be", on the noise regs. The difference between those two numbers is the answer to the question "How much isolation do you need?". With that number in hand, you can then look over the documentation about what types of construction materials and techniques will give you that amount of isolation. That's the best procedure for figuring this out, as it is based on real numbers and proven methods, rather than "guesstimation".

The proposed external walls, (150mm from boundary fence)

so your outside wall is only 15cm from the property line? That makes things a bit harder, since some municipal regulations specify that the noise level must be measured at your property line, not at your neighbour's house.

70mm Hebel aerated concrete panels,

I'm not familiar with that: do you have a link to some information about it? Specifically, you need to know the density, in kg/m3.

As you can see from the drawing, the master bedroom is next door! (no other option in design). Therefore, my main concern is keeping the sound from the rest of the house, as opposed to outside noise coming in.

OK, so you'll also need to pull out your sound level meter again, and measure what levels are acceptable in the rest of the house. We can walk you through how to do that, if you want. But the idea is that you should arrive at a number for how much isolation you need, and based on that design the isolation walls.

1/ Foundation: Will a concrete slab, (as opposed to stumps/bearers/joists) be a better option?

Concrete slab on grade, definitely. Having the floor in direct contact with Planet Earth is a good thing: it acts as a really, really effective damper on vibrations that get into the slab.

2/ Floor: What would be the best floor construction? I've heard differing opinions on whether or not to float the floor.

Here's probably the best explanation of floating floors that I'm aware of: viewtopic.php?f=2&t=8173 and a couple of related threads: viewtopic.php?f=2&t=8134 viewtopic.php?t=8135 And if you really want to get into the technicalities, to fully understand what is involved and how to do it right, then this is arguably the most useful research paper on the matter: http://www.nrc-cnrc.gc.ca/obj/irc/doc/p ... /ir802.pdf

My idea was to build the room on concrete slab, but have a wooden floor (smooth surface for recording acoustic guitar & vocals). Then for drums, have a standard rug or proper drum rug if they exist?

Concrete slab is an excellent surface for a studio, just as it is, provided that the room is treated correctly acoustically. If you look around some of the build threads on the forum, you'll see some pretty amazing things some people have done with their concrete floors, in terms of staining and polishing. However, of you don't like the look of concrete, then other good options are ceramic tiles, linoleum, hardwood flooring, and laminate floor. Personally, I think laminate is a great choice for a studio, but any of the others will also work fine. But the big point here is that there cannot be any air gap between your final finish floor and your concrete slab. Whatever it is you decide on, it must be laid directly on the concrete (perhaps with some type of underlay), but not on a raised platform of any type, for the reasons outlined above in the threads on floating floors. So your basic plan is just fine: Nice wooden floor, with a rug of some type under the drums. Or maybe a drum riser.

3/ Walls: What would be the best wall construction for my scenario?

That will depend on your "number": the one derived from your sound level measurements, about how much isolation you need. But regardless of that actual number, you will need to do the full "room-in-a-room" type of construction to get the type of isolation you are talking about. What will change with the number is the type of materials you'll need, and the total thickness of the wall. The basic concept is simple: You will have four walls around your room anyway, from the house itself, You then need to build a simple stud frame just a few cm away from those existing walls, and put drywall (plasterboard) on only one side of those studs, not both sides, and fill the cavity in between them with fluffy insulation. You do the same for the ceiling, running new joists across the top of your new walls, and hang drywall from that, also with insulation in the gap. That's the overall concept. The new "inner-leaf" room does not touch the existing "outer-leaf" at any point. It cannot, must not, will not. Isolation depends in having the inner-leaf absolutely decoupled from the outer leaf, with not even a single nail bridging the gap. There's more to it than that, of course, but we can get into the details as your planning advances.

4/ Ceiling: Best ceiling construction for my scenario?

See above. The basic concept here is that all sides of the room need to be done to the same level of isolation. If you do the walls to 60 dB and the ceiling to only 35, then 35 is all you get! Think of it like an aquarium: you have to have glass on all sides to keep the water in. You can't replace the glass on one side with cardboard, paper, or a blanket!

5/ Insulation Material: Best stuff to put in the wall cavity?

Either mineral wool or fiberglass. If you go with mineral wool, then the density should be around 50 kg/m3. If you go with fiberglass, then you need about 30 kg/m3. And make it as thick as you can: fill the entire cavity, if your building code allows that. The difference between an empty cavity (no insulation) and a full cavity is pretty impressive. Once again, there's more to it than that, but that's the basic rule of thumb.

6/ Window: Should the external window be acoustically designed, or would it not make that much difference?

I don't see any window marked on your drawing. But in any event, if there is a window, then yes, it should be designed with maximum isolation in mind, and it must be designed as part of the entire isolation system. Basically, this method of isolation relies on the principle of a tuned resonant system, and the way you tune it is mainly by changing the mass on each leaf and by the size of the air gap. So each part of each leaf has to be designed with that in mind, including windows and doors.

7/ Door: Will the double door lock out more sound?

Yes, if done correctly. One door in each leaf is the way to do it. The doors must be solid-core (not hollow or foam filled), thick, heavy, and sealed all around the edges with proper rubber acoustic seals. Once again, there are many details to be considered for doors and windows, but you can get to those as the design progresses. 8 / ... Well, you didn't have a point #8, but you should have! It should be HVAC. Since isolating your room acoustically implies that you'll be putting two very complete air-tight, totally hermit leaves around it, then smothering it with thick layers of thermal insulation, you absolutely do need a proper HVAC system. First, since people have this annoying habit called "breathing", you need to get a steady, constant supply of fresh air coming into the room, and you also need to exhaust the same amount of stale air, at the same rate. Without that, you would use up all the oxygen in the room rather fast, and end up unconscious. But even before you got to that stage, the air would be so stuffy, muggy and lousy that you'd be gagging and gasping. Then there's the problem of temperature and humidity. Since the room is basically wrapped in very thick, efficient blankets, the heat put out by your body, equipment, and lights will build up very rapidly, and since you exhale water vapor with every breath, the humidity will also shoot up pretty fast. So you need air conditioning to keep both of those under control. In this case A/C is not a luxury: it is a basic necessity. Yo won't be able to use that room if you don't have a good HVAC plan. This doesn't have to be complex: Simple ducts, fans, silencers and a small mini-split system is all you need. So you need to take that into account too, as that all takes up space in your walls and ceiling. 9 / Electrical. You'll need lights and power outlets inside, and the electrical system also affects the isolation of the room, so it needs to be considered at the same time. Overall, it looks like you have a nice space there, with realistic goals. With careful design and construction, it can work it rather well, I think. - Stuart -

Hi Stuart, Thanks for getting back to me so quick. It will make my replies look even extra slow! More info about my plans: The rest of the house will be on stumps, only the Music Room, (pictured) will be on a slab. What implications does this have? Should the slab be slightly separated from the ajoining rooms? Ie, not touching the foundations (bearers/joists etc) of the other rooms?

The difference between those two numbers is the answer to the question "How much isolation do you need?".

Being residential, and given the close proximity of bedrooms, should I not just go for maximum isolation? Framework that gives max isolation; flooring that gives max iso; ceiling that gives max iso, insulation that gives....etc. All within reason of course - I don't want to end up with half the room space b/c of half metre thick walls, and ceilings. 70mm Hebel aerated concrete panels, screwed to timber frame and rendered finish.

I'm not familiar with that: do you have a link to some information about it? Specifically, you need to know the density, in kg/m3.

http://www.hebelaustralia.com.au/Pages/ ... eight.aspx I'm wondering if the double leaf assembly will work in my situation, (see pic), except one side will be the external Hebel concrete panel...?

I don't see any window marked on your drawing.

It's in the bottom right corner. Thanks for mentioning the HVAC and the electrical considerations, I hadn't thought about HVAC. My idea is to get a bit more into Google Sketch Up, (I've had a basic go at it) and see if I can draw something that my architect will be able to follow and incorporate into his drawings. It will be a challenge but at least it's a pretty simple design, i.e no separate booths or windows to worry about - just one open room. Do you know of anyone in the Geelong region with experience in this sort of thing? Cheers, Jason.

The rest of the house will be on stumps, only the Music Room, (pictured) will be on a slab. What implications does this have? Should the slab be slightly separated from the ajoining rooms? Ie, not touching the foundations (bearers/joists etc) of the other rooms?

If you can, and if you need extreme isolation, then yes, decoupling the foundations will help. But that would only be justifiable if you have very high isolation needs. Or if you have a huge budget, and really don't mind spending it! :)

Being residential, and given the close proximity of bedrooms, should I not just go for maximum isolation?

What is "maximum isolation"? :) 90 dB? 100 dB? More? Less? There is no such things as absolute, total isolation on planet Earth. There are only degrees of isolation, differences in sound levels, that can be measured in decibels.

70mm Hebel aerated concrete panels, screwed to timber frame and rendered finish.

O took a look at the web site, and the first thing I saw is this: "A high performance lightweight concrete building system". "Lightweight" implies low mass. In fact, the guy in the picture seems to be hold a panel with one hand, while he attaches it with the other! I tried to download the technical data from their website, but they insist that you have to create an account, and I'm not willing to do that: I get enough spam as it is! But if it is lightweight, then it won't be good for isolation. Isolation needs mass.

Do you know of anyone in the Geelong region with experience in this sort of thing?

I haven't been to Geelong in more than 40 years! :shock: Maybe John might know someone there: you could PM him. - Stuart -