Thank-you Stuart for that excellent information, you've answered questions I've been pondering for a very long time! I now understand that under the right circumstances there are exceptions to rules. Very much like music theory itself! The exciting news is that we're almost ready to pour the new concrete slab. There is an existing slab there which is in a very sorry state and during the development of this project (with the unforeseen necessity to take down the existing building in order to safely cut down trees) we've decided we can make the CR a little wider and so we would need to pour concrete anyway. Now that all of the footings have been dug out we will be preparing the foundations for this new slab and I am designing the scheme for the cable troughs under the floor. Before I share that I just wanted to show my plan for the new slab(s) so you guys can correct me if it's wrong. There's two options, option 1: as seen in this google image, is to do independent slabs for each inner and outer wall, completely isolated slabs not touching each other with an expansion seal in the gap. Option 2: Here is a very rushed basic diagram of an idea I had, would this work? I've chosen to show the intersection of the hallway walls and the CR wall next to the hallway as it's the most complicated part: The outer walls will be built upon concrete blocks (sorry, not labelled on diagram!), in-between the blocks there will be concrete for the floor. The CR walls will be built on a floating slab that will float on rockwool insulation and ply. I have seen designs using "pucks" or isolating springs etc, but would they really be necessary in my design? While I'm at it, I realised that I wasn't sure how to face the inside of the most outer wall (marked with "???") should I leave it open to the insulation or can I face it with sheetrock? So those are the two options, I'm interested to know if one is better than the other or if they're just two ways of achieving the same thing bringing about the same results?It's actually not that obvious at all! And it does need some head scratching at first... until you change your point of view, and get that "Eureka" moment... :) It fools a lot of people, I think, so don't feel bad by any means!Though this is obvious to you, this has my head scratching.
Studio build in Wales, UK...again!
Originally posted at johnlsayers.com, topic 21409.
I've been scavenging all sorts of goodies for the build - lots of massive windows and frames, some of them will be usable others will come in handy in the non recording parts of the studio such as the lounge or bathroom. I also went and picked up 6 incredibly heavy fire doors - complete with handles, locks, keys, automatic door stoppers and 3.5" solid glass circular windows in each (see pic) I got the lot for £100 which was too good to turn down.
I've also secured a great deal on 25 rolls of isover space saver loft insulation. it's 10kg/m3 which will be nice and light for filling cavities or making traps. It's a little thick at 150mm but 25 bags at £5 per bag I thought it was worth getting.
I also have a local framer who is going to build the frames to my exact spec and erect them for me. He's incredibly skilled and very very competitive in terms of price.
first things first, I need to finalise my plans and then pour the slab. I almost have half a studio just sitting in the drive way, can't wait to put it altogether :yahoo:
Yet another control room floor plan update.
H 10'10" x W 19'5" x L 23'8"
It meets the Bonello criterion, it's on the edge of the bolt area, listening position is at 37.5%
Soffits are 4'10" at the bottom, tapering out to almost 6' at the top, Speakers are offset in soffits and angled 30 degrees, intersecting about 1' behind head. They will also be angled vertically 5 degrees with the tweeters at about 47" above floor.
For the front wall window I'm going back to 3 panes of glass in a wrap around formation as I need the 2 outer panes to form part of the soffits for the speakers otherwise the soffits will be far too small. (Unless I can simply just 'cut' into the soffits for 1 single larger piece of glass? But then the soffits would not be continuous) This gives me a nice big window as well as nice big soffits.
The side walls next to the soffits are angled 33 degrees from the speakers, and the area behind them will be full of hangers as well as housing some rack gear with doors in front. These areas will be ventilated as will the soffits.
The side walls next to those will have windows so that I can see in to the adjoining room and hallway. This is also a handy way to allow natural light in as those areas will also have windows to the outside world. These walls/windows are angled 3.6 degrees which is enough to keep reflections away from the listener and will also allow me to get a bit more absorption into the side walls.
As the ceiling is vaulted and will be around 13' at its peak this area will be full of hangers which will hang down to make the visible ceiling around 8'. That gives me hangers as long as 4' in the centre. They will all be angled towards the front wall in a tapered fashion.
The soffits running along the rear and sides will house the ventilation ducting as well as low frequency absorption and some lighting. All of the side walls will probably end up being covered in some slats in a 1d binary amplitude diffuser pattern, as well as part of the rear wall just to add some life back into the room but still allowing most of the air into the broadband absorption.
The rear wall can have over 3' of space for hangers plus a large diffuser if needed, and there will still be over 11' of distance to the listening position. (over 14' to the actual solid wall)
I've marked on the floor plan the RFZ created by the angled walls, but that is only rough as it doesn't take in to account the reflections from the board, credenza and obviously the ceiling, but it measures around 4.5' behind the head and around 4' to the sides and in front.
Please let me know what you think, and please rip it apart and tell me if there's anything a miss!
Picked up the fluffy insulation today, when we arrived the lady had even more than she realised so I ended up with over 30 rolls for £125. I thought we were going to have to make 3 or 4 trips to get it, but my dad decided to fit it all on the trailer and in the car in one go - luckily it was only 10 mins down the road. I'm itchy.
Not bad at all for 125! Lucky man!
- Stuart -
Thankyou Stuart! I do indeed feel very blessed. But how about my ideas and design? Any obvious problems with what I’ve come up with?Not bad at all for 125! Lucky man! - Stuart -
Hi guys, I could really do with some advice if any of you have a few moments spare.
I've attached 3 different floor plans for my control room, each one has its own concept. Now I realise that the finer acoustic details cannot be properly worked out at this stage before the room is built or tested, however I gotta start somewhere. so these are concepts only. The idea is to create a room with enough space that I have options later on, but I'd like your opinions on what direction might be the best one to take.
Common to all designs are:
-the listening position (37.5% of room length)
-speakers angled at 30 degrees
-broadband hangers on the rear wall
-broadband hangers on ceiling
-2' soffits for silencers around the perimeter of the ceiling/top of walls also full of insulation
Here's what sets each apart from the other:
A
- based on a John Sayers design (to the best of my knowledge)
- slat side walls angled at 6 degrees
- diffusion on rear wall
B
- based on a hybrid of traditional RFZ and non environment
- front wall and speaker soffits angled around 5 degrees vertically
- angled cloud for more deflection
- front side walls angled at 33 degrees, face can be absorptive or reflective or both
- rear side walls angled at 3.6 degrees, face can be absorptive or reflective or both
- optional diffusion on rear wall if needed
C
- based on non environment concept
- non angled side walls with hangers behind fabric wall
- no diffusion on the rear
- fully reflective front wall
The first picture shows the reflection free zone of A & B (C is mostly absorptive so nothing is shown). This is where I'm a little unsure -by ray tracing I have roughly come up with the RFZ for each marked in grey. Is the criteria for a RFZ simply that any early reflections being deflected off of any surface must reach the listener no sooner than 20ms after the direct sound and attenuated by -20? And as long as that happens the RFZ is effective?
The reason I ask is because I see most guys in the forum building their studios somewhat like my 'A' design with fairly shallow angled slat side walls. But as you can see from the ray tracing, the listening position is completely out of the RFZ (which is in front of the listening position and mainly useless) Now I could place absorptive panels in the first reflection points, but then I don't see the advantage of angling the walls other than to prevent flutter... and in that case absorption would deal with that anyway, and so I don't see the advantage of doing this over plan 'C'; but I see most people just using slat walls... which would suggest reflection as well as absorption and a little diffusion, but surely they would also create problematic reflections straight into the listener's ears? OR is it that I have not taken in to account that the majority of those reflections (outside of the grey area) would reach the listener later than 20ms. Have I understood that correctly? Or does this layout (A) simply not work? one way the listener could get into the grey RFZ is if the mixing desk was not so large, then the listening position could be moved forward.
Now as you can see in plan 'B' the front side walls are angled such that all of the reflections (in the 2D plane at this stage) completely miss the listening position and create a really large RFZ. This design makes a lot more sense to my simple brain. My question is, would this design be hugely advantageous over design 'A' ?
Finally, C - I like the idea of the non environment room for mixing, and it seems as though it would offer the biggest sweet spot of the lot. But what I don't like about the idea is those times when the control room might be used for composing or doing vocal takes the room would be a little lifeless and uninspiring. I fear that clients might not feel completely comfortable in such a room for long periods, and that is concerning to me.
I'm also not clear as to what the pros and cons are for absorption vs deflection when it comes to creating a RFZ? I suppose deflection keeps some energy in the room whereas absorption kills it a little more. But is that the only consideration? Would first reflections still exist in a non environment room at certain lower frequencies?
Thanks for any answers you can give me!
I really wouldn't do that, to be very honest. There are very good reasons for not tilting your front wall. To start with, that implies raising your speakers up higher so that they still aim at your head, which means that you have them above the horizon. The higher you have them, the more off they are. Your ears are designed to produce the flattest, best response for things ON the horizon: that's where the lions, tigers, and other nasty things are, so your brain does best with sounds from those angles. For sounds significantly above the horizon, your perception of frequency is shifted, since the sound waves are hitting your pinna at a different angle. Above 15°, all bets are off, but even at 5° there's a noticeable decrease. Since one of the most basic purposes of having a control room is to get the best possible accuracy you can for frequency, it makes sense to do everything you can to keep the PERCEPTION of that frequency accurate as well. Second, with the speakers up high facing down, your head is only ever on-axis to the speakers at one specific spot. If you move your head forwards, then your ears are below axis, and if you move your head back then your ears are above axis. Speaker response is smoothest and cleanest on-axis. Same rule applies as above. Third, if the speaker is up high pointing down, that puts a lot more reflections of the desk and console directly in your face: can you say "comb-filtering"? It also makes the lower-mid range very uneven and messy. Fourth, it0s really hard to do! Just building a compound structure that is angled in both dimensions is a tough one. It's bad enough with angling in just ONE dimension: two makes it more than twice as hard. Fifth: gravity. If you tilt your speakers down, the soffit baffle is not standing vertically: it is leaning over. It is HEAVY! Putting it in place and keeping it there is an extra problem. So is the speaker mount: the speaker wants to slide out of its mountings, especially under vibration. Etc. So I would discard that as an option. Yes, some people do that: Wes Lachot, for example, often does rooms with tilted front walls. I have done it too (Studio Three, for example). It can work, sure. But it's not as easy as it looks, and you need to work extra hard in the design, and again in the construction, to get it right. Studio Three has an angle of 4.23°... Accuracy is tough! Keep your walls, soffits, and speakers vertical. Life is hard enough already without making it unnecessarily harder.- front wall and speaker soffits angled around 5 degrees vertically
Yes :thu: Once again, studio three has an angled cloud. In fact, the cloud is split into several sections, and hung at two different angles. The front part is steeper. The other room will have a split cloud with only one angle, but it will be angled. I pretty much always angle clouds, unless the ceiling is VERY low. But even then, I angle part of the cloud...- angled cloud for more deflection
Good, but it doesn't have to be! If moving it a couple of points further forward or backward would help, then do it!-the listening position (37.5% of room length)
Same here: Good, but it doesn't have to be! If changing that a couple of degrees either way would improve things, then do it. These numbers (38%, 30°, etc.) are not written in stone: they are just starting points, and you can adjust them a little, as needed.-speakers angled at 30 degrees
Yes!-broadband hangers on the rear wall
Yes! Both of those are needed, and your room seems to be big enough to allow for good diffusion. To give yourself a but more floor space at the back, you can make the hanger section a bit shallower in the middle, but keep it deep in the corners.- diffusion on rear wall
That's rather steep! Why so much? I seldom need to angle those "wings" that steeply.- front side walls angled at 33 degrees,
Both: reflective at head height and a couple of feet each way, absorptive near the ceiling and floor.face can be absorptive or reflective or both
Why? Waste of space....- rear side walls angled at 3.6 degrees,
It will be...optional diffusion on rear wall if needed
It should be shown! You will still have reflections, and there will still be a zone that has none... NER rooms done like "C" will be very dead: that will need a lot of reflective/diffusive surfaces to liven it up again, and meet the decay time specs (BS.1116-3). There's nothing wrong with doing it that way, but then you will need to tune it carefully. I think I already showed you that other thread, but if not, here the link again: viewtopic.php?f=2&t=21368The first picture shows the reflection free zone of A & B (C is mostly absorptive so nothing is shown).
Those are two different pars of the RFZ concept. The first part is that NO first-order reflections arrive at your head. Ever. Nothing. ALL first order reflections are re-directed to the rear of the room, where they are both diffused and absorbed, to create the "diffuse field". That diffuse field must not get back to your ears until at least 20m2 after the direct sound got there, and when it does it should be about 20 dB lower than the direct sound, sustained for a short time if possible, and then decay smoothly and evenly at the correct rate for the room size, with all frequency bands decaying at the same rate, +/- 0.05sIs the criteria for a RFZ simply that any early reflections being deflected off of any surface must reach the listener no sooner than 20ms after the direct sound and attenuated by -20? And as long as that happens the RFZ is effective?
I guess we are looking at things from the opposite perspective, but I would consider "A" to have steeply angled sidewalls! Steep with reference to the angel of the soffit. With that layout, you have a very sharp "knee" where the soffit meets the side wall, and I prefer to avoid that by using a shallower angle. Jut enough to get the RFZ decent.The reason I ask is because I see most guys in the forum building their studios somewhat like my 'A' design with fairly shallow angled slat side walls.
That's becuase your side walls are angled way too much (from my perspective: too little from yours).But as you can see from the ray tracing, the listening position is completely out of the RFZ
Only if you get the angle wrong! :)but I see most people just using slat walls... which would suggest reflection as well as absorption and a little diffusion, but surely they would also create problematic reflections straight into the listener's ears?
Do the math: as a very rough rule of thumb, 1 foot = 1 ms. So measure the DIFFERENCE in distance between the direct sound and the reflected sound: if that difference is LESS than 20 feet, then you have a problem... And even if it is greater than 20 feet, if this is a first reflection, then you are already breaking rule #1: no first-order reflections at the mix position....OR is it that I have not taken in to account that the majority of those reflections (outside of the grey area) would reach the listener later than 20ms.
Yes, that's a better angle, but STILL too steep for y lickings. It still protrudes too far into the soffit, and the room. Reduce the angle further, make your soffit face wider. The wings don't need to be very big to achieve proper RFZ.Now as you can see in plan 'B' the front side walls are angled such that all of the reflections
Right! :thu: Check that against BS.1116-3 and EBU Tech-3276, for decay times... This is one reason why I'm not a big fan of NER.But what I don't like about the idea is those times when the control room might be used for composing or doing vocal takes the room would be a little lifeless and uninspiring.
:thu: Spot on.I fear that clients might not feel completely comfortable in such a room for long periods, and that is concerning to me.
Correct. After all, you spent a lot of money to produce those precis, accurate sound waves, so why kill them as soon as you can? It sounds unnatural, anyway. So keep the energy in the room, but away from your head, then diffuse it and only attenuate it slightly, so that it is outside the Haas criteria. Then it sounds natural, smooth, and your ears can properly determine directionality and perceive correct frequency response. This is why i AM a big fan of RFZ.I'm also not clear as to what the pros and cons are for absorption vs deflection when it comes to creating a RFZ? I suppose deflection keeps some energy in the room whereas absorption kills it a little more.
Supposedly not, but in reality yes. - Stuart -Would first reflections still exist in a non environment room at certain lower frequencies?
Thanks Stuart! while responding to your response I realised one thing I had not accounted for is the speaker coverage angle! So I think I need to understand that better before continuing to design my RFZ.
I have been ray tracing as if there is a full 180 degree coverage angle when in fact that may not be the case; there may only be a 60, 80 or 90 degree coverage angle. Despite having requested this information from Quested, I have not received a reply and cannot find this info published in any of their specs sheets on the web. Now that I think about it, I (think) understand how John's designs work in regards to the side walls... the maximum angle from the speaker coverage dictates where the first side wall reflection will be and therefore an angle of 6 degrees, or 12 degrees should be sufficient in most cases. I suppose what it comes down to is how large do you want your RFZ to be...
The speakers I have consist of 2 10" LF drivers, 1 soft dome MF and 1 soft dome HF. Considering that they are soft dome drivers I imagine the dispersion will be quite substantial so in your experience what would be a good guess as to the speaker coverage angle? 80 degrees?
I really wouldn't do that, to be very honest. There are very good reasons for not tilting your front wall. To start with, that implies raising your speakers up higher so that they still aim at your head, which means that you have them above the horizon. The higher you have them, the more off they are. Your ears are designed to produce the flattest, best response for things ON the horizon: that's where the lions, tigers, and other nasty things are, so your brain does best with sounds from those angles. For sounds significantly above the horizon, your perception of frequency is shifted, since the sound waves are hitting your pinna at a different angle. Above 15°, all bets are off, but even at 5° there's a noticeable decrease. Since one of the most basic purposes of having a control room is to get the best possible accuracy you can for frequency, it makes sense to do everything you can to keep the PERCEPTION of that frequency accurate as well. Second, with the speakers up high facing down, your head is only ever on-axis to the speakers at one specific spot. If you move your head forwards, then your ears are below axis, and if you move your head back then your ears are above axis. Speaker response is smoothest and cleanest on-axis. Same rule applies as above. Third, if the speaker is up high pointing down, that puts a lot more reflections of the desk and console directly in your face: can you say "comb-filtering"? It also makes the lower-mid range very uneven and messy. Fourth, it0s really hard to do! Just building a compound structure that is angled in both dimensions is a tough one. It's bad enough with angling in just ONE dimension: two makes it more than twice as hard. Fifth: gravity. If you tilt your speakers down, the soffit baffle is not standing vertically: it is leaning over. It is HEAVY! Putting it in place and keeping it there is an extra problem. So is the speaker mount: the speaker wants to slide out of its mountings, especially under vibration.- front wall and speaker soffits angled around 5 degrees vertically
Right, but speaker dispersion is not a hard-edged "cone". It's a very blurry, soft edge, and it is different vertically and horizontally. Higher frequencies are projected straight out, more or less like rays, in a fairly tight "cone", maybe 40° wide (20 either side of the axis). Lower frequencies spread out more, perhaps 50° or 60° or so. Still lower frequencies spread even wider: say 80° or 90° As you go further down, the spread gets larger and larger: 120°, 150°, 180°. At the point where the wavelength equals the width of the speaker cabinet, the sound starts to wrap around completely, and below that, you get basically 360° dispersion. But even then, the spread isn't smooth and even: there can be interference patterns created by the speaker itself that cause coverage to change quite drastically at different directions and frequencies. Now for the kicker: the same applies to the reflections off the RFZ surfaces! A high frequency wave will reflect rather tightly, as a "specular" reflections, somewhat like a ray of light, whereas a low frequency wave will sort of "mush" around and "reflect" broadly, at larger angles, blurrily. The larger the reflecting surface, the better focus and specularity you get. (sort of...) Therefore, you need to consider reflections across a rather broad range of frequencies with your ray tracing. At least out to 60° or so each side of the axis.I have been ray tracing as if there is a full 180 degree coverage angle when in fact that may not be the case; there may only be a 60, 80 or 90 degree coverage angle. Despite having requested this information from Quested, I have not received a reply and cannot find this info published in any of their specs sheets on the web. Now that I think about it, I (think) understand how John's designs work in regards to the side walls...
80 degrees at what frequency? :) It's not that easy. Look for a dispersion diagram for your speaker: If the manufacturer doesn't want to give you one, and you also cannot find one on-line in a review or lab test comparison, that's probably a sign that you should look for a different speaker. There are several ways of presenting the data, but a set of polar patterns is a good one, and easy to understand: Something like this: That shows the dispersion for a series of different frequencies, as viewed from above (looking down from the ceiling, on top of the speaker). Another option is the polar intensity diagram, showing how the intensity changes by frequency at various angles off-axis: Harder to read, and not much use, to be honest Yet another is a simple "spread" diagram: But that's just marketing hype; No real use at all for studio design (and neither would I recommend an SRM-450 as a studio monitor! :) ) Another method is the "relative frequency response" graph: A far more useful and complete, but harder to read, method is the full "directivity plot" or "isobar plot": That one contains all the info you need to see exactly how the speaker produces the sound field. The one above shows a really lousy speaker, with major issues. The one below shows a much better speaker: That happens to be for the Neumann KH-120 speaker, which is an excellent, excellent monitor, and has great response across the board, but even so you can see some issues around the cross-over frequency, at roughly 2 kHz. Nothing to worry about, of course, but still visible with this plot. Your speaker manufacturer must be able to supply SOME type of directivity information! If not, that's not a good sign.The speakers I have consist of 2 10" LF drivers, 1 soft dome MF and 1 soft dome HF. Considering that they are soft dome drivers I imagine the dispersion will be quite substantial so in your experience what would be a good guess as to the speaker coverage angle? 80 degrees?
Nope! :)the maximum angle from the speaker coverage dictates where the first side wall reflection will be and therefore an angle of 6 degrees, or 12 degrees should be sufficient in most cases.
That, and how good you want it to be, and how low you want it to extend, in frequency... - Stuart -I suppose what it comes down to is how large do you want your RFZ to be...
Thanks Stuart, those charts are great to see, very interesting how complicated it can get. I knew that dispersion would get bigger and bigger the lower down the frequency response you go, but surely there's little you can do about that in a medium sized room apart from try to attenuate with absorption? but for a RFZ are we not mainly concerned about more directional rays from upper mids and high frequencies? LF will seem to always have an omni-presence. If we do need to deflect LF as well, then surely we would need to have much bigger angles that would require rooms much larger than the ones typically found on this forum? Roger Quested himself has replied to my e-mails, but he hasn't given me specifics yet though I have asked for them, I suspect he's a very busy man. I shall await his reply. in the mean time he simply said 'soft domes have very wide dispersion' which is rather vague.Right, but speaker dispersion is not a hard-edged "cone". It's a very blurry, soft edge, and it is different vertically and horizontally. Higher frequencies are projected straight out, more or less like rays, in a fairly tight "cone", maybe 40° wide (20 either side of the axis). Lower frequencies spread out more, perhaps 50° or 60° or so. Still lower frequencies spread even wider: say 80° or 90° As you go further down, the spread gets larger and larger: 120°, 150°, 180°. At the point where the wavelength equals the width of the speaker cabinet, the sound starts to wrap around completely, and below that, you get basically 360° dispersion. But even then, the spread isn't smooth and even: there can be interference patterns created by the speaker itself that cause coverage to change quite drastically at different directions and frequencies. Now for the kicker: the same applies to the reflections off the RFZ surfaces! A high frequency wave will reflect rather tightly, as a "specular" reflections, somewhat like a ray of light, whereas a low frequency wave will sort of "mush" around and "reflect" broadly, at larger angles, blurrily. The larger the reflecting surface, the better focus and specularity you get. (sort of...) Therefore, you need to consider reflections across a rather broad range of frequencies with your ray tracing. At least out to 60° or so each side of the axis.I have been ray tracing as if there is a full 180 degree coverage angle when in fact that may not be the case; there may only be a 60, 80 or 90 degree coverage angle. Despite having requested this information from Quested, I have not received a reply and cannot find this info published in any of their specs sheets on the web. Now that I think about it, I (think) understand how John's designs work in regards to the side walls...80 degrees at what frequency? :) It's not that easy. Look for a dispersion diagram for your speaker: If the manufacturer doesn't want to give you one, and you also cannot find one on-line in a review or lab test comparison, that's probably a sign that you should look for a different speaker. There are several ways of presenting the data, but a set of polar patterns is a good one, and easy to understand: Something like this: That shows the dispersion for a series of different frequencies, as viewed from above (looking down from the ceiling, on top of the speaker). Another option is the polar intensity diagram, showing how the intensity changes by frequency at various angles off-axis: Harder to read, and not much use, to be honest Yet another is a simple "spread" diagram: But that's just marketing hype; No real use at all for studio design (and neither would I recommend an SRM-450 as a studio monitor! :) ) Another method is the "relative frequency response" graph: A far more useful and complete, but harder to read, method is the full "directivity plot" or "isobar plot": That one contains all the info you need to see exactly how the speaker produces the sound field. The one above shows a really lousy speaker, with major issues. The one below shows a much better speaker: That happens to be for the Neumann KH-120 speaker, which is an excellent, excellent monitor, and has great response across the board, but even so you can see some issues around the cross-over frequency, at roughly 2 kHz. Nothing to worry about, of course, but still visible with this plot. Your speaker manufacturer must be able to supply SOME type of directivity information! If not, that's not a good sign.The speakers I have consist of 2 10" LF drivers, 1 soft dome MF and 1 soft dome HF. Considering that they are soft dome drivers I imagine the dispersion will be quite substantial so in your experience what would be a good guess as to the speaker coverage angle? 80 degrees?Nope! :)the maximum angle from the speaker coverage dictates where the first side wall reflection will be and therefore an angle of 6 degrees, or 12 degrees should be sufficient in most cases.That, and how good you want it to be, and how low you want it to extend, in frequency... - Stuart -I suppose what it comes down to is how large do you want your RFZ to be...
I completely agree with you, it would be a lot harder to do. There's a couple of reasons why I would need to angle them if I went with this design though: It would make my soffits larger since they would taper out at the top (see dotted line in design) otherwise I would be under the minimum recommended width without that angle. This way the top of the soffit would be about 6' and the bottom would be about 4' 10" the middle point would be over 5' Although not drawn in the design, I will also have a couple pairs of near fields. The idea with angling the mains is so that the near fields do not block the mains as much as they would without the angle. I remember reading in this forum (perhaps even written by yourself) that if one is to angle the soffits then 5 degrees is about the maximum you can do before it starts to make a real big difference, though I agree ideally they should not be tilted at all.I really wouldn't do that, to be very honest. There are very good reasons for not tilting your front wall. To start with, that implies raising your speakers up higher so that they still aim at your head, which means that you have them above the horizon. The higher you have them, the more off they are. Your ears are designed to produce the flattest, best response for things ON the horizon: that's where the lions, tigers, and other nasty things are, so your brain does best with sounds from those angles. For sounds significantly above the horizon, your perception of frequency is shifted, since the sound waves are hitting your pinna at a different angle. Above 15°, all bets are off, but even at 5° there's a noticeable decrease. Since one of the most basic purposes of having a control room is to get the best possible accuracy you can for frequency, it makes sense to do everything you can to keep the PERCEPTION of that frequency accurate as well. Second, with the speakers up high facing down, your head is only ever on-axis to the speakers at one specific spot. If you move your head forwards, then your ears are below axis, and if you move your head back then your ears are above axis. Speaker response is smoothest and cleanest on-axis. Same rule applies as above. Third, if the speaker is up high pointing down, that puts a lot more reflections of the desk and console directly in your face: can you say "comb-filtering"? It also makes the lower-mid range very uneven and messy. Fourth, it0s really hard to do! Just building a compound structure that is angled in both dimensions is a tough one. It's bad enough with angling in just ONE dimension: two makes it more than twice as hard. Fifth: gravity. If you tilt your speakers down, the soffit baffle is not standing vertically: it is leaning over. It is HEAVY! Putting it in place and keeping it there is an extra problem. So is the speaker mount: the speaker wants to slide out of its mountings, especially under vibration. Etc. So I would discard that as an option. Yes, some people do that: Wes Lachot, for example, often does rooms with tilted front walls. I have done it too (Studio Three, for example). It can work, sure. But it's not as easy as it looks, and you need to work extra hard in the design, and again in the construction, to get it right. Studio Three has an angle of 4.23°... Accuracy is tough! Keep your walls, soffits, and speakers vertical. Life is hard enough already without making it unnecessarily harder.- front wall and speaker soffits angled around 5 degrees vertically
So the next thing then is how about diffusion behind the client couch? How do I make sure it sounds okay for the clients with diffusion right behind their heads?- diffusion on rear wall Yes! Both of those are needed, and your room seems to be big enough to allow for good diffusion.
so this is in relation to the soffits, the angle as measured from the side wall would be 27 degrees. The idea is to make the RFZ as large as possible with the space that I've been given, a shallower angle would reduce the size of it.- front side walls angled at 33 degrees,That's rather steep! Why so much? I seldom need to angle those "wings" that steeply.
I guess it depends on how big I would like that RFZ to be. From the ray tracing I've been doing, If I reduce them, the angle changes and makes the RFZ smaller. Now I could use absorptive side panels, but then I don't see any benefit in having soffit wings at all. Though they do protrude into the soffits at the bottom, because the soffits would be angled, at the top the soffits are very wide indeed. The other reason is it would allow me to fit some rack gear behind doors which would justify losing that space, and also provide a little isolation for slightly noisy rack gear. I can come up with an amended design following your recommendations, but in the mean time after clarifying a few things would design 'B' work well for the basis of a control room that (with the right testing and treatment) could meet spec and allow for an honest mixing environment in your opinion?- rear side walls angled at 3.6 degrees Why? Waste of space.... [\quote] Yes perhaps, but there will be windows there. Granted they don't necessarily need to be angled, and I could always angle them vertically instead, so that reflections go towards the floor or ceiling, but I would also get a little more absorption on that wall if I angle itI guess I have been looking at designs where the width is narrow, and so people have to make do with what they're given, hence a lot of studios seem to have that very sharp knee, being effective RFZ for a dispersion of 30 or so degrees either side.I guess we are looking at things from the opposite perspective, but I would consider "A" to have steeply angled sidewalls! Steep with reference to the angel of the soffit. With that layout, you have a very sharp "knee" where the soffit meets the side wall, and I prefer to avoid that by using a shallower angle. Jut enough to get the RFZ decent.Yes, that's a better angle, but STILL too steep for y lickings. It still protrudes too far into the soffit, and the room. Reduce the angle further, make your soffit face wider. The wings don't need to be very big to achieve proper RFZ.
1) Keep the couch far enough in front of the diffuser that it won't have too much of an effect (in other words, good distance between couch and diffuser: move the couch forward a few feet) 2) Tune it high enough that it doesn't have too much of an effect (remember the "3 times lowest scatter wavelength" rule...) 3) Keep the diffusion high, slightly above the ear height of the folks seated on the couch. 4) Use a diffuser design that gives a smoother response at closer distances. Fractal-based designs are good for that. Of course, you'll need to compromise on some of those, probably, due to room size restrictions and practicalities, but take into account that the guys on the couch are not really doing critical listening: they are there to be blown away by the bass, and by your mixing skills. They don't really need as much pure acoustic clarity and precision as you do, at the mix position. If the producer is sitting back there and has a comment on the sound, then invite him to take a few steps forward and listen again where you are. But with your size room, and good treatment, that's unlikely. I reckon your room will sound pretty darn good.So the next thing then is how about diffusion behind the client couch? How do I make sure it sounds okay for the clients with diffusion right behind their heads?
No it wouldn't.- Think it through.... You seem to be not seeing the forest, only the trees... :) Don't be afraid to change sizes and angles all over the place!so this is in relation to the soffits, the angle as measured from the side wall would be 27 degrees. The idea is to make the RFZ as large as possible with the space that I've been given, a shallower angle would reduce the size of it.
And how would that help to make them wider where they NEED to be wider, which is where the actual drivers are? I think if you check, you'll find that you are making them NARROWER at that point by tilting them down... unless you star the tilt very low, and make the tilt angle very large... which has the drawback of REDUCING space for treatment under the speaker...It would make my soffits larger since they would taper out at the top
Why do you want to angle your rear windows?Yes perhaps, but there will be windows there. Granted they don't necessarily need to be angled, and I could always angle them vertically instead, so that reflections go towards the floor or ceiling,
Why do you think you need thick absorption on the side walls, so far back in the room?but I would also get a little more absorption on that wall if I angle it
Take a look at Studio Three, and tell me about the "sharp knee"... :) Also, take a look at the other thread I linked you to, and tell me about the sharp knee... :) Studio Three is a large room, the other one is a small room. In both cases, there is no sharp knee. It IS possible to do that, if you are prepared to be flexible and keep on trying all kinds of tricks, until you optimize each part as much as it can, with the best compromises all over.I guess I have been looking at designs where the width is narrow, and so people have to make do with what they're given, hence a lot of studios seem to have that very sharp knee, being effective RFZ for a dispersion of 30 or so degrees either side
To a certain extent, yes, but not as much as you seem to be thinking.I guess it depends on how big I would like that RFZ to be.
Then you are not doing something right! My guess would be that you are always starting the wing at the same point, never changing that.... try again with different starting points for the wing.From the ray tracing I've been doing, If I reduce them, the angle changes and makes the RFZ smaller.
Nope. I would avoid that. Use absorption above and below the central panel of the wing, by all means, if you need to, but not at speaker height.Now I could use absorptive side panels,
Why? Why do you think that's a good thing, when there is no sound source up at the top of the soffits? The sound source is way down low in the soffit....at the top the soffits are very wide indeed.
How much extra rack space do you need? How much rack gear do you plan to have in there? There's lots of space in the desk, in the desk wings, and in the gondola behind the mix position: Will you need more than that? And even if you do need more rack space, to me it seems like there would still be plenty of room for that in the sides of the soffits, and maybe even in the wings. What's the total amount of RU that you need?The other reason is it would allow me to fit some rack gear behind doors which would justify losing that space,
Desk wings, with silencers?and also provide a little isolation for slightly noisy rack gear.
"B" is a good starting point, but I would re-do the wings as outlined above: Make them smaller, shallower angle, shifted over. Improve your RFZ like that, make your soffit baffles larger, gives you some rack space too, and does not require tilted soffits, with all the complications they create, for very little benefit. - Stuart -I can come up with an amended design following your recommendations, but in the mean time after clarifying a few things would design 'B' work well for the basis of a control room that (with the right testing and treatment) could meet spec and allow for an honest mixing environment in your opinion?
Thank-you Stuart. Yes I have had a good look at Studio 3 but can't remember seeing a floor plan? I would love to see one if you have it? Okay, I have had a real good play around with the angles and of all the ones I tried, this seems to be what I like best. I tried moving my listening position forward, moving the speakers forward, different speaker angles, making the wings shorter, narrower, longer, wider, tried different angles etc etc. What I found was by making the side wings shorter, the RFZ became shorter but wider, and by making the wings longer, the RFZ became narrower but longer. I found that an angle of 25 degrees (in relation to the side walls) is a nice length and a nice width. You can see in my second diagram the extremes of the first reflections where the room angles change, (dotted lines are the reflections) it makes the RFZ 5 1/2' long at the tip, and about 8' wide. Of course, that's NOT taking into account the reflections from the credenza or the desk it self. I've also angled the rear treatment in at 12 degrees but leaving a flat part in the middle for the diffuser, and moved the couch out about 2 1/2' The treatment in the corners would be over a meter thick, or rather a meter of hangers. I got rid of the tilt of the soffits and now they are a straight up 5' wide, with the speakers offset. The speakers fire to a 'point' which is 16" behind the head. Now, according to Quested they recommend that the listener is between 80cm - 100cm in from the tip of the triangle, do you think I should adjust my design to accommodate this based on their advice? The other thing I am slightly worried about is the front window. It's now going to be stuck out further from the rest of the wall, the framing comes out into the room to meet the edges of the speaker soffits. It means the length of the room where the window is is now close to 22' which is close to the average height of my ceiling (10' 10"). So I have a couple of questions: 1. should I even care? especially since the ceiling is actually vaulted, going from 8' 10" - 12' 10", 10' 10" just being the average, so does it even matter anyway? 2. If it does matter then theres a second length dimension that would work well which is 23' 1", so do the soffits need to have a nice smooth transition to the middle where the window is or I could I just have a cut out where the window would be? As in, carry the angle on towards the middle of the front wall, but cut into it in order to reveal the window which is further back than the soffits? As long as the soffits are still the same width. Also, now that the side walls and side windows are straight, is there any chance of flutter occurring? Especially if I decide to use slats? Or would the slats eliminate flutter? How about the window? I know that the speakers will be firing off axis to the side walls, so there won't be direct flutter from them, but how about from other sources or secondary reflections?1) Keep the couch far enough in front of the diffuser that it won't have too much of an effect (in other words, good distance between couch and diffuser: move the couch forward a few feet) 2) Tune it high enough that it doesn't have too much of an effect (remember the "3 times lowest scatter wavelength" rule...) 3) Keep the diffusion high, slightly above the ear height of the folks seated on the couch. 4) Use a diffuser design that gives a smoother response at closer distances. Fractal-based designs are good for that. Of course, you'll need to compromise on some of those, probably, due to room size restrictions and practicalities, but take into account that the guys on the couch are not really doing critical listening: they are there to be blown away by the bass, and by your mixing skills. They don't really need as much pure acoustic clarity and precision as you do, at the mix position. If the producer is sitting back there and has a comment on the sound, then invite him to take a few steps forward and listen again where you are. But with your size room, and good treatment, that's unlikely. I reckon your room will sound pretty darn good.So the next thing then is how about diffusion behind the client couch? How do I make sure it sounds okay for the clients with diffusion right behind their heads?No it wouldn't.- Think it through.... You seem to be not seeing the forest, only the trees... :) Don't be afraid to change sizes and angles all over the place!so this is in relation to the soffits, the angle as measured from the side wall would be 27 degrees. The idea is to make the RFZ as large as possible with the space that I've been given, a shallower angle would reduce the size of it.And how would that help to make them wider where they NEED to be wider, which is where the actual drivers are? I think if you check, you'll find that you are making them NARROWER at that point by tilting them down... unless you star the tilt very low, and make the tilt angle very large... which has the drawback of REDUCING space for treatment under the speaker...It would make my soffits larger since they would taper out at the topWhy do you want to angle your rear windows?Yes perhaps, but there will be windows there. Granted they don't necessarily need to be angled, and I could always angle them vertically instead, so that reflections go towards the floor or ceiling,Why do you think you need thick absorption on the side walls, so far back in the room?but I would also get a little more absorption on that wall if I angle itTake a look at Studio Three, and tell me about the "sharp knee"... :) Also, take a look at the other thread I linked you to, and tell me about the sharp knee... :) Studio Three is a large room, the other one is a small room. In both cases, there is no sharp knee. It IS possible to do that, if you are prepared to be flexible and keep on trying all kinds of tricks, until you optimize each part as much as it can, with the best compromises all over.I guess I have been looking at designs where the width is narrow, and so people have to make do with what they're given, hence a lot of studios seem to have that very sharp knee, being effective RFZ for a dispersion of 30 or so degrees either sideTo a certain extent, yes, but not as much as you seem to be thinking.I guess it depends on how big I would like that RFZ to be.Then you are not doing something right! My guess would be that you are always starting the wing at the same point, never changing that.... try again with different starting points for the wing.From the ray tracing I've been doing, If I reduce them, the angle changes and makes the RFZ smaller.Nope. I would avoid that. Use absorption above and below the central panel of the wing, by all means, if you need to, but not at speaker height.Now I could use absorptive side panels,Why? Why do you think that's a good thing, when there is no sound source up at the top of the soffits? The sound source is way down low in the soffit....at the top the soffits are very wide indeed.How much extra rack space do you need? How much rack gear do you plan to have in there? There's lots of space in the desk, in the desk wings, and in the gondola behind the mix position: Will you need more than that? And even if you do need more rack space, to me it seems like there would still be plenty of room for that in the sides of the soffits, and maybe even in the wings. What's the total amount of RU that you need?The other reason is it would allow me to fit some rack gear behind doors which would justify losing that space,Desk wings, with silencers?and also provide a little isolation for slightly noisy rack gear."B" is a good starting point, but I would re-do the wings as outlined above: Make them smaller, shallower angle, shifted over. Improve your RFZ like that, make your soffit baffles larger, gives you some rack space too, and does not require tilted soffits, with all the complications they create, for very little benefit. - Stuart -I can come up with an amended design following your recommendations, but in the mean time after clarifying a few things would design 'B' work well for the basis of a control room that (with the right testing and treatment) could meet spec and allow for an honest mixing environment in your opinion?
That looks pretty good, yes. If you did the ray-tracing and it all works out to a decent reflection free zone, then all is well! However, that's only the horizontal plan view: you'll need to do the same for the vertical (elevation) view, then check on the diagonals, too. Sound is 3D, not just 2D!What I found was by making the side wings shorter, the RFZ became shorter but wider, and by making the wings longer, the RFZ became narrower but longer. I found that an angle of 25 degrees (in relation to the side walls) is a nice length and a nice width. You can see in my second diagram the extremes of the first reflections where the room angles change, (dotted lines are the reflections) it makes the RFZ 5 1/2' long at the tip, and about 8' wide. Of course, that's NOT taking into account the reflections from the credenza or the desk it self.
Sounds good.I've also angled the rear treatment in at 12 degrees but leaving a flat part in the middle for the diffuser, and moved the couch out about 2 1/2' The treatment in the corners would be over a meter thick, or rather a meter of hangers
:thu:I got rid of the tilt of the soffits and now they are a straight up 5' wide, with the speakers offset.
Check what the horizontal dispersion is for all frequencies, off-axis, and see how far each ear is off axis. As long as you are inside the area with full coverage for all frequencies, then you are fine.The speakers fire to a 'point' which is 16" behind the head. Now, according to Quested they recommend that the listener is between 80cm - 100cm in from the tip of the triangle, do you think I should adjust my design to accommodate this based on their advice?
The window doesn't have to be in line with the soffit baffles. Take a look at the other thread I linked you to. In some of the photos you can see how we did it there.The other thing I am slightly worried about is the front window. It's now going to be stuck out further from the rest of the wall, the framing comes out into the room to meet the edges of the speaker soffits.
In theory, that's a good thing, but in practice it is possible to have different planes there.. Once again, take a look at that thread.so do the soffits need to have a nice smooth transition to the middle where the window is
Between the side walls: yes, probably, but that's easy to fix. You will need treatment on those walls anyway, so it's just a matter of adapting it so it s good fr flutter too. For the glass: it doesn't have to be straight! Just because the SOFFIT baffles are vertical does not mean that the glass also has to be vertical. You can angle the glass if you want to... I angled the glass in that room to help deal with light glare. But even if you do leave the glass vertical, you won't have issues with flutter in the front-back axis, because the rear wall is deeply bass trapped and has a large diffuser on it to. No flutter can ever form there.Also, now that the side walls and side windows are straight, is there any chance of flutter occurring?
Flutter doesn't depend on speaker angles: it depends on wall angles. If you have parallel walls, there's a chance you'll end up with flutter problems regardless of which way your speakers are aiming. Sound is a 3D field that fills the entire room, not just straight lines that follow exact geometric path, like rays do. Ray-tracing helps to understand which way sound will be going, but it's only a rough guide because sound is not rays! Sound is waves, and waves have curved "fronts" that hit walls at various angles, and bounce off at various angles, depending on the frequency, the wall materiel, and the angle of incidence, among other things. So flutter can happen any time sound happens to find a path between two parallel surfaces, regardless of which way that sound originally came out of the speakers. Fortunately, it's easy to treat. - Stuart -I know that the speakers will be firing off axis to the side walls, so there won't be direct flutter from them, but how about from other sources or secondary reflections?
Thank-you Stuart for your reply.
It's been a little while since I've posted an update so here's a big one for you all.
We have a structure up! without boring you all with a boring story it's been up and down but miraculously we have something that resembles a room.
The short of it is, we unknowingly hired cowboys who should never have taken on the job, even though it is an incredibly simple job that still managed to make a mess of it. The structure is not perfectly square, the ridge beam is made up of two beams with a central truss... the truss is off centre.... ridge is like a slightly bent banana. BUT believe it or not it ended up being a million times better than the first TWO attempts... yes. sigh. I could go on.... but I shan't.
So we now have a frame with 18mm OSB on the outside. Just to remind you I am building this studio in stages due to budget and time restraints, and I've started unusually with my inner leaf rather than outer. I will add the outer leaf at a later stage, but having the inner leaf constructed first will allow me to get a lot of my gear that is either in storage or cluttering up our house or my parents house all setup in one place.
Since the inner leaf is temporarily exposed to the outside world, weather proofing is required though eventually will not be needed once it is all covered with the outer leaf, so the roof is just felted for now with a 1' overhang all around. This will eventually be cut off when the outer leaf goes up.
This week I've been weather proofing the OSB walls with a brush on stain solution. Believe it or not OSB is incredibly resilient to moisture in the short term... it's been untreated like this for over 2 months and within that time we've had almost non stop rain and the worst storm to have hit the UK in over 30 years... so bad that everywhere near rivers was flooded and there has just been an insane amount of rain fall as well as 80mph winds. The studio in its naked state has survived it as if nothing happened. Of course I would not recommend leaving it untreated forever but it's nice to know that 1. it didn't blow down and therefore must be strong enough to cope with the weather here and 2. it has not turned into a soggy mess. I was very surprised about this and I was planning to felt or clad it to protect it, but it appears to be bone dry inside and stain should be enough. so for those of you using OSB and are worried about rain, it seems there is no immediate reason to worry too much. The OSB looks as virgin as the day it was installed.
My next job will be to get the temporary doors on and then get the drywall layers up. I am building this inside out so I will beef up the OSB with 2x 15mm drywall layers backer rodded and caulked and held in with cleats in each bay between the studs. The ceiling I will use 'beef up modules' made from frames and inserted in to the bays.
My only questions for now are:
1. despite it appearing dry inside is there a chance that moisture could soak through the OSB from the outside (even with the weatherproofing stain) and then causing the drywall to get damp? This is my main worry as it would be hidden. If there is a chance of this then I will install a damp proof membrane internally on the OSB before putting the drywall layers.
2. if the answer to the above is no, then should I install a vapour barrier for internal moisture? In the UK we rarely do this on our homes, but if we were to do it then it would go on the warm side of the insulation... now as I am building this inside out does that mean it should go over the insulation facing inside the room or behind the insulation between the insulation and the drywall layers?
Any help on this would be great as I do not want to trap moisture by installing either 1 or 2 in the wrong place.
Hooray!We have a structure up!
This sucks, but I feel your pain.believe it or not it ended up being a million times better than the first TWO attempts... yes. sigh. I could go on.... but I shan't.
Interesting for sure. Fingers crossed that goes okay.I've started unusually with my inner leaf rather than outer.
How long do you expect to leave this current structure exposed to the elements?1. despite it appearing dry inside is there a chance that moisture could soak through the OSB from the outside (even with the weatherproofing stain) and then causing the drywall to get damp? This is my main worry as it would be hidden. If there is a chance of this then I will install a damp proof membrane internally on the OSB before putting the drywall layers.
Barrier would go inside your room, covering up the insulation. Greg2. if the answer to the above is no, then should I install a vapour barrier for internal moisture? In the UK we rarely do this on our homes, but if we were to do it then it would go on the warm side of the insulation... now as I am building this inside out does that mean it should go over the insulation facing inside the room or behind the insulation between the insulation and the drywall layers?
Hey Greg! Good to hear from you, thanks so much for your help all the way through my thread so far it means a lot to me. I haven't checked out your build diary since the last time I posted before last, so I am going to check it out in a minute! I plan to have the stained OSB exposed for around a year or so, that's the plan though as we all know, plans often don't go to plan... BUT my father has a structure built from stained OSB which has lasted over 10 years now with zero maintenance... the OSB has not swollen or deteriorated in any way, though he does not have any drywall pressed up against it on the inside so cannot be sure it would not be a problem. What are your thoughts? So barrier goes over the insulation, so in effect it will be the very last thing to go on before the fabric. In that case, could I just wrap my insulation in plastic like John and others have done? Would that be as effective as a vapour barrier? Now, if I install a damp proof membrane on the OSB inside (before the drywall goes on) and then wrap the plastic/vapour barrier over the insulation, will that risk trapping moisture in and make the drywall damp? Or does it not work like that? I'm really sorry for my noob ness on this issue and beg for your guidance. Many thanks and happy thanksgiving!Hooray!We have a structure up!This sucks, but I feel your pain.believe it or not it ended up being a million times better than the first TWO attempts... yes. sigh. I could go on.... but I shan't.Interesting for sure. Fingers crossed that goes okay.I've started unusually with my inner leaf rather than outer.How long do you expect to leave this current structure exposed to the elements?1. despite it appearing dry inside is there a chance that moisture could soak through the OSB from the outside (even with the weatherproofing stain) and then causing the drywall to get damp? This is my main worry as it would be hidden. If there is a chance of this then I will install a damp proof membrane internally on the OSB before putting the drywall layers.Barrier would go inside your room, covering up the insulation. Greg2. if the answer to the above is no, then should I install a vapour barrier for internal moisture? In the UK we rarely do this on our homes, but if we were to do it then it would go on the warm side of the insulation... now as I am building this inside out does that mean it should go over the insulation facing inside the room or behind the insulation between the insulation and the drywall layers?
I'm doing my best to help people out where I can! I haven't updated my thread in a while. I just updated it.Hey Greg! Good to hear from you, thanks so much for your help all the way through my thread so far it means a lot to me. I haven't checked out your build diary since the last time I posted before last, so I am going to check it out in a minute!
My brother had his subfloor exposed for about a month of heavy rain and it is all swollen and screwed up.What are your thoughts?
This is tricky because the warmest side would be your insulation when you're building an inside out inner leaf. However, if I were you, before you build your outer leaf, I would wrap the outside of your inner leaf with barrier. That's where I would put it.So barrier goes over the insulation, so in effect it will be the very last thing to go on before the fabric.
I believe you are referring to what these guys have done in terms of acoustic treatment, not in terms of building code stuff.In that case, could I just wrap my insulation in plastic like John and others have done? Would that be as effective as a vapour barrier?
Since you're building your room the opposite of normal, this does pose an issue. You might have to put up a barrier inside (in front of your insulation) for now, and then tear it down once you build your outer leaf. GregNow, if I install a damp proof membrane on the OSB inside (before the drywall goes on) and then wrap the plastic/vapour barrier over the insulation, will that risk trapping moisture in and make the drywall damp? Or does it not work like that? I'm really sorry for my noob ness on this issue and beg for your guidance.
Thanks Greg, some good ideas there. While I continue my research on preventing moisture build up I have another question regarding the new concrete slab that will be poured in the new year. We didn't get a chance to pour the new slab before the frame was constructed for various reasons, but it's not a big deal as it can be poured after and it will shield it from getting rain dimples. So the structure is built on blocks, which are built up on the original slab on grade. All covered with a damp proof membrane and then 100mm celotex rigid insulation is on top of that. This is for thermal purposes. My question is: Should I line the sides with celotex insulation as well and pour the new slab into the middle or should the new slab connect to the blocks at the edges? I've attached 2 images to illustrate what I mean. If I line the sides then it will reduce thermal bridging, but it may create a flanking path for sound... though the sound will just be met by more concrete, so perhaps it doesn't matter?I'm doing my best to help people out where I can! I haven't updated my thread in a while. I just updated it.Hey Greg! Good to hear from you, thanks so much for your help all the way through my thread so far it means a lot to me. I haven't checked out your build diary since the last time I posted before last, so I am going to check it out in a minute!My brother had his subfloor exposed for about a month of heavy rain and it is all swollen and screwed up.What are your thoughts?This is tricky because the warmest side would be your insulation when you're building an inside out inner leaf. However, if I were you, before you build your outer leaf, I would wrap the outside of your inner leaf with barrier. That's where I would put it.So barrier goes over the insulation, so in effect it will be the very last thing to go on before the fabric.I believe you are referring to what these guys have done in terms of acoustic treatment, not in terms of building code stuff.In that case, could I just wrap my insulation in plastic like John and others have done? Would that be as effective as a vapour barrier?Since you're building your room the opposite of normal, this does pose an issue. You might have to put up a barrier inside (in front of your insulation) for now, and then tear it down once you build your outer leaf. GregNow, if I install a damp proof membrane on the OSB inside (before the drywall goes on) and then wrap the plastic/vapour barrier over the insulation, will that risk trapping moisture in and make the drywall damp? Or does it not work like that? I'm really sorry for my noob ness on this issue and beg for your guidance.
Your images illustrate you trying to float a new slab inside your building. You should just leave it as is. Your outer leaf should have it's own decoupled slab poured. Sorry if I'm not properly understanding your idea here. I hope I've made my response clear enough!
Greg
You’ve understood correctly, and the reason for this is because as I explained earlier in my thread the original slab is very rough, it was never done properly as the building was original just a farm building, it was never insulated and it was not level at all. This new slab is just to have a nice level and smooth floor. I know the ideal is to completely redo the slab but that was not an option. Yes my outer walls will be built on their own slab and foundation. So with that in mind I’m wondering whether to pour the slab to the edge or leave a gap so that I can avoid thermal bridging. Hope that clears things up? Thanks againYour images illustrate you trying to float a new slab inside your building. You should just leave it as is. Your outer leaf should have it's own decoupled slab poured. Sorry if I'm not properly understanding your idea here. I hope I've made my response clear enough! Greg
Acoustically speaking, I doubt leaving the gap would negatively affect things. I think you should be asking a structural engineer their opinion. Also, realize that you're going to be losing height in your room. Are you sure you don't want to just use some thin leveling compound? GregSo with that in mind I’m wondering whether to pour the slab to the edge or leave a gap so that I can avoid thermal bridging.
Does it need to be insulated? I'm not familiar with the climate where you live, but if you don't have a problem with extreme cold such that the ground freezes deep down in winter, then I'm not sure you need to have it insulated. Yes, it should save on energy costs if you do that, but is that a big issue?it was never insulated and it was not level at all.
If that is the MAIN goal, then as Greg said, just get it leveled! A layer of leveling cement correctly applied would do the trick of getting it smooth, flat, and level, at lower cost, and faster. Putting down laminate flooring on to of that, over a suitable thermal and acoustic underlay, would give you an excellent floor.This new slab is just to have a nice level and smooth floor.
But you ARE completely re-doing the slab! You are pouring a totally new slab with all the same issues involved as in pouring any slab. The only difference is that you are not taking out the old slab first... A few hours with a jack hammer and a few guys with shovels and wheelbarrows would solve that problem. The you could, indeed, insulate properly, and lay a proper slab, without losing ceiling height...I know the ideal is to completely redo the slab but that was not an option.
And where will your INNER walls be built??? I hope you were not intending to build them on the slab as shown in your diagram! You can't just build load-bearing walls on the edge of any old thin floated slab, without having the slab properly designed for that purpose! You need a structural engineer to tell you how thick to make the slab edges such that the can support the load of the entire inner-leaf rooms... where to put the rebar, what type of rebar, how many pieces. how to tie it together, whether or not you need mesh as well, what grade of concrete to use... Designing and pouring a floated structural slab is not something you should attempt on your own: hire a structural engineer.Yes my outer walls will be built on their own slab and foundation.
... and acoustic bridging, too! If you are going to all the complexity and expense of laying a separate structural slab for your inner-leaf, then you might as well make the extra effort to make sure that it is a true isolated, floated slab, to maximize your acoustic isolation. - Stuart -So with that in mind I’m wondering whether to pour the slab to the edge or leave a gap so that I can avoid thermal bridging.
Thank-you Greg and Stuart, really appreciate your replies. Sorry for my rubbish quoting skills in this forum, I haven't quite put the time in to learning how to do it properly yet! I did think about just screeding the floor, but I decided purely for thermal reasons that I want to insulate as best as I can, and the screed would not work well over the insulation as it would probably crack due to how thin it is. Typically in the UK on new builds you actually have to insulate it to meet code. Plus, we do indeed have very very cold winters here and having first hand experience of walking on un-insulated slabs even in mild weather it has convinced me even more of wanting nice cosy feet. I think it'll be more comfortable for artists that come in as well as a lot of them I have worked with previously love to walk around in just socks or bare feet. The insulation we use for slabs is called celotex, its a very thick and rigid insulation almost like a spray foam but in slab form. This is for structural purposes more than anything else as it gives a nice flat and stable surface for the concrete to be poured on to. Of course it will compress, but not as much as Rockwool etc. As I say, it is designed for this purpose and is used on all new builds all over the country. Stuart, I hate to scare you but yes the new INNER walls are built on the pre-existing slab. I had the slab checked over by a friend who is a structural engineer, and it was found fit for purpose. The old slab had a previous timber frame building on it, which was a little smaller. When we took this building down I extended the foundations and existing slab on the side. Around the perimeter I cemented a row of 9" hollow blocks and filled the blocks with a little sand and then concrete. The new structure is bolted to these blocks which sit on the slab. When I build the outer walls they will be built on their own separate foundation and perimeter slab. This was why I am asking the question about the 'new inner' slab. To gap or not to gap? You answered by saying it would be better to leave a gap to avoid acoustic bridging, but was this answered knowing that my inner walls will not be sitting on this new slab? BTW, when I designed the control room I already accounted for the new slab and ceiling height, so I am not concerned with that as the height will be correct once the new slab is in place. Thanks again!Does it need to be insulated? I'm not familiar with the climate where you live, but if you don't have a problem with extreme cold such that the ground freezes deep down in winter, then I'm not sure you need to have it insulated. Yes, it should save on energy costs if you do that, but is that a big issue?it was never insulated and it was not level at all.If that is the MAIN goal, then as Greg said, just get it leveled! A layer of leveling cement correctly applied would do the trick of getting it smooth, flat, and level, at lower cost, and faster. Putting down laminate flooring on to of that, over a suitable thermal and acoustic underlay, would give you an excellent floor.This new slab is just to have a nice level and smooth floor.But you ARE completely re-doing the slab! You are pouring a totally new slab with all the same issues involved as in pouring any slab. The only difference is that you are not taking out the old slab first... A few hours with a jack hammer and a few guys with shovels and wheelbarrows would solve that problem. The you could, indeed, insulate properly, and lay a proper slab, without losing ceiling height...I know the ideal is to completely redo the slab but that was not an option.And where will your INNER walls be built??? I hope you were not intending to build them on the slab as shown in your diagram! You can't just build load-bearing walls on the edge of any old thin floated slab, without having the slab properly designed for that purpose! You need a structural engineer to tell you how thick to make the slab edges such that the can support the load of the entire inner-leaf rooms... where to put the rebar, what type of rebar, how many pieces. how to tie it together, whether or not you need mesh as well, what grade of concrete to use... Designing and pouring a floated structural slab is not something you should attempt on your own: hire a structural engineer.Yes my outer walls will be built on their own slab and foundation.... and acoustic bridging, too! If you are going to all the complexity and expense of laying a separate structural slab for your inner-leaf, then you might as well make the extra effort to make sure that it is a true isolated, floated slab, to maximize your acoustic isolation. - Stuart -So with that in mind I’m wondering whether to pour the slab to the edge or leave a gap so that I can avoid thermal bridging.