Ian New Studio in narrow room. Single storey with flat roof

Hi everyone. After lots of learning, planning and expert help I've finally learned enough to start the build of my studio. The room used to be split in two as two seperate rooms. I've knoocked down the dividing wall. It is a single story side extension on my house running the full length of the house with a flat roof to the outside. The dimensions are: width: 2.35m Height 2.22m Length 10.04m I'm going to post some pics from before I started then progress through the build. I've got a sketchup which gives the rough idea of the way things are going to pan out although the original plan was to not do a room in room design due to space limitations but that has now changed, at least for the live room which I'm currently building. I first beefed up the existing ceiling (above which is a flat roof to the outside as it is only single story) but then after testing, the beefing up alone wasn't going to give enough isolation so I'm sacrificing space in the live room for isolation. I'm not that bothered about isolation from the control room to outside but if there is enough space, that may go room in room as well. I'm going to see how it goes. The sketchup is below. I know its an unusual design but I've been speaking to some experts from the forum (who I wont name in case they dont want me to) and we decided this was the way to go. It is going to be an inside out construction for the walls and possibly for the ceiling in the control room as well (yet to be finalised). Anyway, it's been a massive learning curve to get to this stage so I want to post the build in the hope it helps anyone facing similar problems I've faced with the limited dimensions of the room. I've also still got a few questions which I'll post as I go :-)

welcome Ian - your .skp post didn't make it - want to try again ??

Still trying John - All I keep getting is "The file is too big, maximum allowed size is 500 KiB." Tried with a 796k skp and tried zipping it to 650 but still getting the message. Any ideas?

simple Ian - just get rid of the computer component which is unnecessary and here it is. maybe it's because i have admin rights - but the admin board says you can post up to 800Kib. can some one check it out for me as I can only log on as admin.

Cheers John. I was getting the same result with the file zipped up though which was only 632kb. Heres some pics of the room stripped out with the original dividing wall taken down and the plasterboard ceiling taken down:

Then we measured out the dimensions of the live room room in room to see if it will be big enough. It's gonna be tight but worth the loss of space for the massive gain in isolation:

The roof to the outside world is some measly wood covered by roofing felt on the outside:

So we beefed it up to increase the mass by using 15mm soundbloc drywall cut to size for the gaps and stuck in to place with an even coating of drywall adhesive on the back of each piece so there were no air gaps when pushed up in to place. We used 2 layers of soundbloc ie 30mm increase in mass. Second layer again held in to place using drywall adhesive and then nails in to the supporting timbers either side to give it extra support. The adhesive worked really well. We used loads and loads of acoustic caulk to fill the gaps. Also beefed up the side bits while I was at it and caulked them up too:

Once that painstaking pain in the ass job was out of the way, the framing for the live room could begin:

I'm still not sure how the ceiling is gonna work. The walls are gonna be inside out but the ceiling is not. If you look at these next pics, you'll see that at the back end of the room I've cut the back wall higher than the others. Tthis was the first wall I did but I think I may have made a mistake with it and may have to lower it to the same height as the others and put a new top piece in. My original thinking was that the ceiling boards would go under this top piece and attach to it and be sealed up to the drywall on the higher wall if you see what I mean. I'm not sure thats right so I cut the wall the other end at the lower height and this looks more logical. It's a relatively easy fix once I've made my mind up (or if anyone can advise me, that would be great) as to which is right:

We've now started drywalling the back of the first wall (the longest one behind the drum throne in the pics), again using 2 layers of 15mm soundbloc with the blue side facing in to the room, not towards the wall, caulking the edges of the first layer before moving on to the second. No pics yet as we're still doing it. I've got a question. I've got hold of some neoprene like dense foam. Used by Adlib audio for making the insides of flight cases. It's about a centimetre thick but compresses nicely down to 0.5cm. I'm thinking, should I cut strips of this and put them on the underside of the walls to float them? I know its not proper floating but I'm thinking it may aid isolation. I could then used it under the laminate floor as well to give similar isolation. The downside as I see it is that, given the limited space I have, once the walls are in place, it will be difficult to get behind 2 of them to caulk up the bottom edge of the walls at the back so it may do more harm than good having them floating on this stuff. I'm hoping someone will be able to tell me whether you think this is an advisable thing to do or not. Cheers guys. Heres a pic of the neoprene like foam:

Ian - why not do something like this with your ceiling.

Hi John, Thats an interesting design. It would save height as there surely then would be no need for a cloud? Question for you. Doing it this way would mean more timber acting as the mass of the ceiling compared to the standard way which would be 2 layers of drywall right across. Does timber have as good isolating properties as 30mm of drywall?

in a simple reply - Yes! 35mm of timber would have the same properties a 30mm of drywall - the bonus is you end up with a diffusive ceiling that absorbs. 2 birds with one stone as we say ;)

Excellent. Looks like thats the way to go then. Thanks John. What gap should I leave between the new ceiling structure and the existing structure (ie up in between the gaps of the existing rafters)? Should I stick to 5cm or go for a bit more? 5cm is the air gap I've left along the walls. Then I guess, use some thin flexible insulation in the air gap but not touching the outside structure just sitting on the top of the new ceiling...? I'm going to use solid batts of Rockwool RWA45 for insulating the insides of the walls the the 'internal' voids of this new ceiling structure.

Yes :)

Anyone got any thoughts on whether I should use the foam to float the walls?

i floated my control room walls but not my vocal booth walls and I can tell the difference when a big truck goes past. I would float them.

Cool, cheers D I'll float them then.

Got a question. Concerning the room in room live room, I've left a 4.5-5 cm air gap between the new room and the existing structure. If I put a thin layer of insulation across the backs of the inside out walls, it will take up some of this air gap, although will only be coupled to the internal and not the external structure. This will reduce the air gap which is bad but add insulation and conform to Johns design recommendations which is good. I'm trying to decide if its the right thing to do and if so, any recommendation for the best stuff to use. There is some acoustic roll available which is 2.5cm deep which takes up about half of the air gap. What do you think? Cheers Ian

Also, do I need to worry about density with this stuff?

Concerning the room in room live room, I've left a 4.5-5 cm air gap between the new room and the existing structure.

Not enough. You need an air gap of at least 10cm in order to keep the MSM resonant frequency down low enough (distance between the leaf surfaces!, NOT between the frames). Unless you plan to use a huge amount of mass on both leaves...

If I put a thin layer of insulation across the backs of the inside out walls, it will take up some of this air gap,

No it wont! The insulation will be IN the air gap. In fact, the entire air gap should be filled with insulation (rock wool or fiberglass) for maximum isolation. If you do not fill the air gap with insulation, then you compromise isolation seriously, losing anywhere from 6 to 15 dB...

although will only be coupled to the internal and not the external structure.

It won't be coupled if you use the correct density, and don't over-fill. You want just enough to fill the gap, or a bit less. It will only flank (couple) if you jam it in too tight, or if you use stuff that is too dense.

This will reduce the air gap which is bad but add insulation and conform to Johns design recommendations which is good.

It does not reduce the air gap: it is part of the air gap, and it is very, very good.

I'm trying to decide if its the right thing to do and if so, any recommendation for the best stuff to use.

Right thing to do? Absolutely! Without insulation in your air gap, the resonance is not damped.

There is some acoustic roll available which is 2.5cm deep which takes up about half of the air gap.

Way too thin! You need at least 10cm, which is one reason why the air gap should be at least 10 cm...

Also, do I need to worry about density with this stuff?

48 kg/m3 (roughly). - Stuart -

^ But isn't 48 kg/m3 to much? I thought Owens corning 703 had this density and was too dense for this purpose (isolating not treating a room) I thought all you guys recommended that pink fluffy stuff which has a density of like 28 kg/m3. Please correct me if I’m wrong. Adolfo

Here are predicted results with Insul (http://www.insul.co.nz/). Double frame wall, 100mm (4in) air gap fully filled with wool : - With rockwool (48kg/m3) : freq TL 50 15,3 63 15 80 14,1 100 20,2 125 28,5 160 33,2 200 38,3 250 43,5 315 48,9 400 54,5 500 59,7 630 59,7 800 62,9 1000 65,6 1250 67,5 1600 68,6 2000 65,9 2500 56,5 3150 62,2 4000 68,8 5000 74,9 STC 53 OITC 32 - With fiberglass (22kg/m3) : freq TL 50 15,3 63 15 80 14,1 100 20 125 28,1 160 32,6 200 37,5 250 42,5 315 47,7 400 53,1 500 58,1 630 57,9 800 60,9 1000 63,4 1250 65,1 1600 66 2000 63,1 2500 53,5 3150 59 4000 65,4 5000 71,3 STC 52 OITC 32 The 48kg/m3 rockwool seems a little better.

Viewing these tables it really seems as if 48 kg is a little bit better, maybe they keep suggesting the not that dense fiber glass because of the price, because I think comparing price vs. money, if you don't have that much of a budget you better go for the fiber glass. Or am I wrong again: P? I don’t really know the prices for these two different products in your country.