Is there a magic size?

Ah ok now i see! You mean internal walls as in if i was building a control room, live room and vocal booth, those partition internal walls?

I'm not sure I understand your comment: All walls are built the same way... How many rooms are you going to have? - Stuart -

Soundman2020 wrote:

Ah ok now i see! You mean internal walls as in if i was building a control room, live room and vocal booth, those partition internal walls?

I'm not sure I understand your comment: All walls are built the same way... How many rooms are you going to have? - Stuart -

He was referring to the comment I made about the picture from Rod's book showing plasterboard on both sides of an isolated wall. I said that could only be on an internal wall because plasterboard is not weather resistant and therefore couldn't be used as an external wall outer leaf top layer. He's only doing a single room. Dan

Ah thanks Dan, really really appreciate that. So with those new calculations you put in, I’d be getting about 67db of isolation correct? (Not expecting things to be bang on just there or thereabouts) Is it possible to use this MSM calculator for doing a wall with RISC/resilient channels? I figured it’s still MSM even though it’s semi decoupled and not a true room within a room. I reckon I could save money and get adequate results doing RISC clips/resilient channel. My goal was 50db isolation, but the more I think about it, I think I may have been a touch over zealous there. Maybe more like 40-45db would be more realistic. Walls for that would be 2 layers of OSB outside, Stud wall, RISC clips, 2 layers of Plasterboard inside The only thing that freaks me out with doing the 2 leaf method is having to buy 2 sets of doors, 2 sets of windows - essentially doubling up on price. Yes Stuart we was just on about the walls in between, I was getting confused, again :lol:

elastic wrote:

Ah thanks Dan, really really appreciate that. So with those new calculations you put in, I’d be getting about 67db of isolation correct? (Not expecting things to be bang on just there or thereabouts) Is it possible to use this MSM calculator for doing a wall with RISC/resilient channels? I figured it’s still MSM even though it’s semi decoupled and not a true room within a room. I reckon I could save money and get adequate results doing RISC clips/resilient channel. My goal was 50db isolation, but the more I think about it, I think I may have been a touch over zealous there. Maybe more like 40-45db would be more realistic. Walls for that would be 2 layers of OSB outside, Stud wall, RISC clips, 2 layers of Plasterboard inside The only thing that freaks me out with doing the 2 leaf method is having to buy 2 sets of doors, 2 sets of windows - essentially doubling up on price. Yes Stuart we was just on about the walls in between, I was getting confused, again :lol:

Not 67dB really. You can't just add the figures for each leaf. You look at the graph underneath which gives you estimated isolation for frequencies. At 40Hz (around Bass guitar Low E string) it estimates about 55dB of isolation and raises to around 73dB for frequencies over 315 Hz. So it depends how bass heavy your music is. You can't use the MSM calc for resilient clips as it doesn't account for the flanking, so anything above 40-45 dB isolation will be passed through pretty much. It's true you need two sets of doors for a double frame wall, but that's the price for good isolation. You wont save much money by going for a single door though. To get 40dB of isolation in a single door is a huge task. You will need it to be massively heavy. 75kg/m2 or for a standard door around 175kg! (385lb in old money!) you would need it to be lead lined for that and have probably 6 extra heavy duty hinges and massive framing and support all around the door and it's stops. Aswell as multiple seals and an industrial door closer, just to stop it slamming and taking a finger off. Look at Rod's "super door" design for ideas. That will get you maybe 40dB isolation. Your windows definitely need to be double glazed, but not standard double glazing, you need thicker glass, so should be bought as individual panes and made up on site. You will almost certainly save money using resilient channels/clips but you will struggle to get anything more than 45dB isolation overall. And your door will probably cost the same as two doors built as MSM. The windows will be the same either way, but if they're both in the same wall it will maybe cap at 40dB isolation due to flanking. So overall you will save money on the walls, but not other things really and lose probably 10dB of isolation maybe more at low frequencies. Dan

Right ok, that’s super info Dan, cheers mate! Answers a lot, I shall stick with the 2 leaf system. I’ve put in bob golds Calc and the amroc calculator my internal dimensions : 5.5m x 3.5m x 2.5m It passed all 3 BBC tests and was just in the bolt area too. Those dimensions give me 48m3 and 19m2 - I think that’s pretty good from what I’ve learned so far? Stuart I remember you said 40 cubic and 20 floor space was a minimum for a decent room so I’m quite happy there. Funnily enough when I increase the room length to 6m it puts me on the border of the bolt area, what looks like a worse position on the bolt map than before. I would’ve thought increasing the size would be better. I’m probably misreading something? I’m still weighing up pushing to 6m x 3.5m x 2.5m - it just depends how thick the walls will be. At the moment I’ve calculated my walls to be about 30cm thick overall (that’s 2 layers of OSB, stud, 2.5cm air gap, stud and 2 layers of plasterboard) Quick question too, should I be too concerned about these tree roots and my base? The trees will be about 1m / 1.2m from the base.

Also, quick question - if I have a 2.5m ceiling inside, should I be ok with the exterior being 3m high at the front sloping slightly to the back? I’ll be 1m from the fence so will go through the planning route. The lower the better externally for financial reasons and to keep the neighbours ok. Thanks

elastic wrote:

Funnily enough when I increase the room length to 6m it puts me on the border of the bolt area, what looks like a worse position on the bolt map than before. I would’ve thought increasing the size would be better. I’m probably misreading something? I’m still weighing up pushing to 6m x 3.5m x 2.5m - it just depends how thick the walls will be. At the moment I’ve calculated my walls to be about 30cm thick overall (that’s 2 layers of OSB, stud, 2.5cm air gap, stud and 2 layers of plasterboard)

Again, in the case of rooms this size, any gain in volume is almost always preferred, unless it throws you wildly out of wack with the ratio, or makes the room asymmetrical. As long as the 6m x 3.5m x 2.5m passes all three BBC tests you should be fine. If you can afford it and fit it in, then go for 6m in length.

elastic wrote:

Quick question too, should I be too concerned about these tree roots and my base? The trees will be about 1m / 1.2m from the base.

Ideally you want trees at least the same distance away from your foundations as they are tall. So a tree that is 2m tall should be at least 2m away from your foundation. If not then you may need some additional professional advice for your foundations.

elastic wrote:

Also, quick question - if I have a 2.5m ceiling inside, should I be ok with the exterior being 3m high at the front sloping slightly to the back? I’ll be 1m from the fence so will go through the planning route. The lower the better externally for financial reasons and to keep the neighbours ok.

You really need to design your studio (on SketchUp) before you can make these kind of decisions. For example, it might be a good idea to fit your ventilation silencer boxes into the ceiling/roof of your studio and you would need to have enough space for them. You need to consider what kind of roof design you are doing too. A cold roof requires ventilation (meaning you'll need to go three leaf), whereas a warm roof requires different materials for construction. You might be able to get away with a little less than 3m height at the low end, but you'll have to work out the complete roof design before you'll know for sure. Of course you could put on the planning application you want a 3.2m height and then you're safe either way, if it's approved, if they say to lower it, then you can lower it a bit. Dan

[quote=“Waka”] No problem 8). For decoupled room within a room you build two free standing rooms. The outer frame has 4 walls and roof trusses/joists sitting on it. The inner frame has 4 walls and ceiling joists sitting on it, and doesn't touch the outer framing at all, at any point. [/quote] Thanks Dan, I’ve been reading your last post about hot roof/cold roof and doing some research. I’m struggling to picture how the roof attaches to the walls. Forgive my lack of knowledge. I kept re reading your quote above, but can’t quite picture it. I’m hoping to chat with my Uncle today who’s a carpenter who will hopefully help with the build and has done loads of roofs, so he might be good to explain it too. Main things re roof would be to save space. Any suggestions and ideas on what you think I’d be best doing would be appreciated :) Thanks

elastic wrote:

Thanks Dan, I’ve been reading your last post about hot roof/cold roof and doing some research. I’m struggling to picture how the roof attaches to the walls. Forgive my lack of knowledge. I kept re reading your quote above, but can’t quite picture it. I’m hoping to chat with my Uncle today who’s a carpenter who will hopefully help with the build and has done loads of roofs, so he might be good to explain it too. Main things re roof would be to save space. Any suggestions and ideas on what you think I’d be best doing would be appreciated :) Thanks

If you have a look at my build thread to see how I built my roof. I went with a ventilated cold roof and three leaf design for ease of construction. The outer roof joists just sit on the outer walls. And are nailed to the top plate (you can get timber frame joist clips too) Then inside the room you build your inner walls a bit shorter and sit another set of joists on these walls for your ceiling. My roof design is like this (remember it's three-leaf) Outer walls 3m height, joists sitting on top of these with a 100mm rise over the 4m run. OSB3 T&G roof deck > Epdm rubber sheet glued to the deck > raised trims on three edges and a gutter trim on the lowest edge. In between the joists I have loft insulation and about 100mm of air gap above it for air flow. This is my ventilation, it is not sealed. The underside of the roof joists is my sealed "outer leaf" and consists of OSB3 > plasterboard > plasterboard, with each layer caulked. Now on to the inner leaf: The internal walls are built about 2.35m tall, and a new set of joists are sat on top of these. Insulation sits ontop off these joists filling up to the outer leaf. I wanted an inside out ceiling, so I built ceiling modules and fitted them between these joists. The modules were just two layers of 15mm plasterboard on frames and screwed into the sides of the joists. There is a 200 - 300mm cavity between my inner ceiling and outer leaf to allow me to fit my silencer boxes in and also maintain isolation even though I'm using three leaf design and an inside out ceiling. You can look at my build thread for details (it's still ongoing) : http://www.johnlsayers.com/phpBB2/viewtopic.php?f=10&t=21269 Dan

Super Dan, thanks for such a detailed reply. It always helps :) And your thread looks ace. It’s a lot easier to understand with pictures and when someon explains it. Been a week off from the project so just getting back into it now. Does the HVAC unit have to be in above the ceiling? Also, forgive my lack of knowledge, but what is an inside out ceiling? Thanks :D

elastic wrote:

Super Dan, thanks for such a detailed reply. It always helps :) And your thread looks ace. It’s a lot easier to understand with pictures and when someon explains it. Been a week off from the project so just getting back into it now. Does the HVAC unit have to be in above the ceiling? Also, forgive my lack of knowledge, but what is an inside out ceiling? Thanks :D

Sorry for the long delay on replying, I've had a busy week. You can put your silencers and HVAC ducts wherever you want/can fit them. It could be useful to save space by putting silencers inside the speaker "soffits", if you're flush mounting your speakers. Some people put the ducting/silencers along the inside top corner of the walls. It doesn't really matter where you put them, as long as you design them correctly and keep the room symmetrical (definitely in front of you, and preferably behind aswell). An inside out ceiling, is based on John's (John Sayers, you're on his forums :lol:) design. It can be used on walls and ceilings. When you frame a wall, instead of putting the plasterboard on the room side of the frame, you put it on the cavity side of the frame. This leaves the framing exposed to the room, which is a ready made framing to support your acoustic treatments. You can put mineral wool /glass wool in this framing and face it with slats to build tuned helmholtz all over the room (John's signature design), or leave it exposed as absorption, and/or combine the two. You can see the design in John's construction guide here: http://johnlsayers.com/Recmanual/Titles/Acoustics3.htm. He calls it "My Wall", as this was written before the term "inside out walls" was coined. Dan