Rod's Place. Small studio design in Hilton West Australia.

Hi there all. I'm helping a mate out with a studio design for his back shed. It's a fairly limited space, especially ceiling height, which at the moment is 2680 at it's highest and 2230 at it's lowest. Take at least 170 off for ceiling bearers and it's getting pretty low. The existing design has only 140mm ceiling bearers and the interior height is already looking something like just over 2100mm at the lowest point of the control room. (rear). We may be able to tie the joists to pre-existing ceiling bearers, that way we may be able to get away with 90x45s, but I'm going to have to have another look at the space before I can make that decision. Thought I'd run the design past everyone to see if there's any obvious pitfalls. The only thing I was thinking is that the live room, (which is sunken by 190mm), has two parallel walls. I could angle the back wall of the live room as well, but would lose space, which is already limited. I could angle the dividing wall between the two rooms, but this would involve some trickery with the stepdown, which wouldn't be a huge issue, I guess. Another issue may be the preexisting sliding glass door, which is currently right behind the proposed desk. This could seriously mess with the image from the monitors, no? Moving it, however, would be another expense I'm not sure we could spare. The budget is very tight, I think I'll be sourcing any timber and other materials/doors etc from Gumtree or any other secondhand sources we can find. Any thoughts? Is it worth the extra headscratching and amatuer engineering to angle the dividing wall? Is this door worth moving, even if it means breaking the budget? Any thoughts greatly appreciated. Stu

I'm really wondering about some of the design concepts here, rather than the specific questions. For example, you mention that the lowest point of the CR ceiling is at the REAR, when in reality it should be lower at the FRONT. The basic concept should be that of a funnel, with the narrowest point where the speakers are and only getting wider, in all dimensions, from there back. Or at the very least, staying straight. If that is the only possible layout for the rooms, then I would adjust the height of the inner-leaf ceiling so that it is not parallel to the outer-leaf roof, and at the very least keep it parallel to the floor. Then there's the stairs: I would be rather skeptical about having a huge hole in the rear corner of the room, right where deep bass effects are a their greatest, and with no way of treating it. Who know what resonant effects that extra cavity will have on the room acoustics. That's without even considering the issue of isolation: How do you plan to complete the inner-leaf down that stairwell? That isn't shown in the model, and is critical to the isolation of the entire studio. The stairs are only 80cm wide, so there doesn't seem to be enough space down there to complete the inner-leaf on both sides, and still have room to walk up the stairs. You also ask several questions that involve the roof, but you don't actually show the roof in the diagram, so it's hard to figure out how the inner-leaf ceiling will interact with that. Depending on how the rafters/joists are arranged up there, you might be able to build the inner-leaf ceiling "inside out", which would gain you the entire dimension of your joists in room height. In other words, you might not need to lose those 17cm of height, acoustically, if it is feasible to build the ceiling inside out. So please add the detail of the existing roof to your model, especially the rafters and/or joists that are up there, as well as anything that is currently hanging fro them. Pictures could help too! On the same point: you are only spanning 341 cm, so I don't see the need for 2x8 joists: Unless you are planning a massively heavy load up there, the span tables I have say that pretty much ANY type of wood will span that distance in 2x6, which is probably something like 38x140 where you live. And if you reduce the spacing from 16OC to 12OC (40cm), there are even some types of wood that might be able to span that with 2x4 (38x90), although I wouldn't risk that myself. But I'm not a structural engineer, and I have no idea what your build code says, so it would be better for you to call in a real structural engineer and ask for his recommendation on that. You could save yourself several cm up there by careful planning of your ceiling layout, and careful selection of lumber.

We may be able to tie the joists to pre-existing ceiling bearers,

Not sure what you mean by "ceiling bearers". but if you are referring to existing joists in the outer leaf, then there is no way to tie the two together without flanking across the MSM air cavity, unless you want to go with expensive options like proper acoustic ceiling hangers. But you seem to be on a tight budget, so that is probably out of the question.

The only thing I was thinking is that the live room, (which is sunken by 190mm), has two parallel walls.

And why is that a problem? It also has two splayed walls, which are wasting a LOT of space, and are opposite each other, not even adjacent: Why is that? Is there something in those gaps that makes it impossible to use the full width of the room? Pillars? Pipes? Ducts? Something else? If there is nothing there, then why waste all that space? It is a myth that walls MUST be non-parallel in a studio: yes they can be non-parallel, and often are for one of several reasons, but the problems that are avoided by having non-parallel walls can also be dealt with in other ways, if necessary. And if you really do need splayed walls to control flutter, for example, then with a wall that long you could take half of the wall out, then bring the other half back in, in an inverted "V" shape, thus saving space.

Another issue may be the preexisting sliding glass door, which is currently right behind the proposed desk. This could seriously mess with the image from the monitors, no?

Absolutely, yes. It is right at the place where you need major absorption. For a small room like that, the entire rear wall should be thick absorption, so having glass there makes no sense at all. Finally, there's the issue of the control room geometry: If I'm reading that right, your mix position is going to barely 4cm from the REAR WALL!!! :shock: At least, I'm assuming that the angled panels at the front left and right of the room are supposed to be speaker soffits, but they are so far apart, and angled so shallowly that the intersection of the acoustic axis occurs practically at the rear wall, which is about 200cm too far back. The entire front end needs re-designing to correct that issue. There is also that strange "kink" at the top of the soffits, angled inwards at 12°, whose purpose is not clear. Is that going to be some sort of bass trap? Considering all of the above, if that were my place, I would switch the control room and live room around: Put the live room over the stairs, and put the control room over on the right, facing towards the LR, not side-on, with or without splayed walls, as needed (depending on your basic design concept). (And of course, if the are splayed, it would then be in the opposite direction, and could theoretically be less than half the length of the room, if you happen to be using RFZ as the basis.) That would give you freedom to treat the CR correctly, remove the issue of the stairwell "resonator" cavity, and greatly improve your sight lines, and set up the front geometry correctly (speakers, mix position, etc.) That would be my suggestion. Maybe others have different opinions. - Stuart -

Thanks for the reply Stuart. The ceiling angle can't be changed, as that's how the existing roof is, and I don't want to lose any more height. I'll have a play around with swapping the rooms, it's a good idea, especially with that sliding door where it is. I have designed a double hinged door to go over the stairwell, and up the wall where the cavity is, so that will essentially be usable floorspace, but would also probably work better in the live room. That's a good idea to build the ceiling inside out. Would you have acoustic insulation stapled to the gyprock and then cloth stretched over some thin panels, so from the roof it would go: gyprock/gyprock/stud/acoustic insulation/cloth, or would you leave the ceiling as a reflective surface? It would make sense to make it non reflective, ya? As for the ceiling joists, I'll check with a mate regarding a reduction in spacing to distribute the load, we may be able to get a reduction in the depth of timber needed. Building codes over here are fairly strict, to span that length is a 170mm at least. But yes, I would assume that reducing the spacing would help. Another good idea to do a V instead of slicing a whole section of the room. I'll work that into the next design. Lots of good stuff to think over. I'll get back to y'all with an update. Thanks again for your thoughts Stuart. Stu

The ceiling angle can't be changed, as that's how the existing roof is, and I don't want to lose any more height.

The ceiling and the roof do not have to follow the same line. That's why I asked about adding the roof structure to your model, so we can see what is up there, and what can be done with it. There are options, but we can't see which ones would work / not work if you don't show us what it looks like right now. This is an issue you are going to have to deal with, anyway, for the control room, regardless of which side you have the control room on. If you are going to all this trouble and expense to build a control room, it makes no sense at all to build it wrong, with flawed acoustics designed in from the beginning! It is critical that the control room is symmetrical, and that includes the ceiling, so if you can't get the ceiling angled the correct way, then at the very least get it flat and deal with the issues caused by that arrangement in the normal manner. Having it dip down behind you, or even worse having it lopsided across the room, is not going to work. It would be a shame to build this place, then discover that the acoustics are unworkable and your mixes don't translate... Sacrificing a few cm of height to get the acoustics good in the control room is a small price to pay. Besides, from a quick test of your room ratio, it might not be a bad idea at all! :)

I have designed a double hinged door to go over the stairwell, and up the wall where the cavity is, so that will essentially be usable floorspace, but would also probably work better in the live room.

You mean like a trap door of some sort? That's a good idea, but it still has to go "somewhere" when it is open, meaning that the "somewhere" it goes cannot be used for acoustic treatment. So here to, it makes sense to have that in the live room, not the control room. In fact, it might even be useful for changing the acoustic response of the live room: With that cavity down there, having the door open o closed should make a noticeable difference to room response. But how are you going to do the seals on that door? Seals are critical for isolation (perhaps the single most important item, after mass), and it's already hard enough to get them right on a normal door, so it's going to be a real challenge to do them on double-fold trapdoor.

Would you have acoustic insulation stapled to the gyprock and then cloth stretched over some thin panels, so from the roof it would go: gyprock/gyprock/stud/acoustic insulation/cloth,

Exactly, yes. Although you can't staple the insulation to the drywall! The normal way of holding it in place is to stretch wire mesh, string, plastic or something similar across the bottom of the joists (or even better, just inside the bottom of the joists), so the insulation rests on that. And the cloth does not need to be "stretched over thin panels": just attach it directly to the joists.

or would you leave the ceiling as a reflective surface? It would make sense to make it non reflective, ya?

Yup! If the floor is hard and acoustically reflective (which is practically always the case), then the ceiling needs to be soft and absorptive, simply in order to deal with flutter echo, but even more important to provide enough surface area for sufficient overall room absorption: With the amount of glass and doors you have in there, it looks like you might be getting short on space for that. It's a small room, so a very large percentage of the inner surface area is going to need absorption in it, to get the reverb times down in line with ITU specs.

As for the ceiling joists, I'll check with a mate regarding a reduction in spacing to distribute the load, we may be able to get a reduction in the depth of timber needed. ... I would assume that reducing the spacing would help.

It will: Simple physics! :) If you have more joists closer together, they can support more weight with the same deflection. Check the standard span tables. In most cases, if you halve the spacing then you can support double the load, all other factors being equal.

Building codes over here are fairly strict, to span that length is a 170mm at least.

That's surprising! Code where I live (Chile) is the toughest in the world, as we are the nation most prone to earthquakes on the surface of the planet! We've learned over the years that things need to be tough, and even our code does not require such major strength. And our code seems to work, since there were very, very few code-compliant buildings damaged in the 8.8 magnitude quake that struck here a couple of years back... including in my own garage, where I'm spanning roughly the same distance and load with simple pine 2x6's... So I'm surprised that there would be a building code that requires even greater structural strength than that. Doesn't make much sense. It's only 11 feet and change, so it hardly seems necessary to use 2x8's Are you sure that you read the code tables correctly? Not that I'm advocating that you should use less if more is required! Far from it. It's just that it seems strange. - Stuart -

Hi all. I've worked up a new floor plan, still haven't sussed out the ceiling, so for the purposes of this post, it's just a 2D projection. I'm wondering what the best use of space vs sound quality would be for the live room. At this stage I have the room fairly square, with only one wall with angled treatment. The room has a ratio of 1:1.48:1.9, but that's if I can keep the average ceiling height at 2300. Is it worth sacrificing some floor space to angle the walls a bit? Or will this not be a problem with the favourable ratio? I also thought we could build half the walls inside out, providing an absorbing wall opposite every reflective wall? Thanks, Stu

Is it worth sacrificing some floor space to angle the walls a bit?

Probably not. You can always add poly-cylindrical diffusers and absorption panels on the walls, as needed. I'd maximize the space, if that were my room.

I also thought we could build half the walls inside out, providing an absorbing wall opposite every reflective wall?

Makes sense! :) - Stuart -

Thanks for the feedback Stuart, think we're getting close here. Cheers, Stu