New Live Room at Giant Wafer Studios

[TornadoTed]

Ok so I am not 100% on getting the best isolation possible without spending the Earth.

When the shell is up I will have a single skin 6" concrete wall on all 4 sides, my plan was to build a room within a room.

Originally we had decided on one stone wall but for various reasons it wasn't practical so settled on one end wall made from RPG Diffusorblox sat on this,

SWW Masonry Isolation - Mason UK - Acoustic Engineers

The other 3 walls will be 6" x 2" timber inside out walls with 2 sheets of plasterboard facing the cavity, we plan to do this so the acoustic treatment sits between the studs to save space. I planned to sit them on this,

W Pad - Mason UK - Acoustic Engineers

Most of the walls will have 4" of RW3 with a 2" air gap behind and cloth and wooden slats over the front. I have also come up with a novel diffusor panel made from oak offcuts they sell as firewood. I will try to get a picture up today.

I intend to sit 9" x 2" purlins on the 2 side walls just under the current roof, again an inside out design so the acoustic treatment can fit betweeen the purlins. On the lower parts of the ceiling (anything below 12' or so) we intend to use 3" DIY Space Couplers, 3" RW3 and a 3" air gap behind which will fit perfectly betweeen the purlings. I have bought some bamboo sheets to make the couplers, I did try a couple of prototypes over here,

SPACE COUPLERS. Theory, construction and effectiveness on traps.

The higher part of the ceiling will either be left as plastered with exposed purlings or perhaps have some poly diffusors installed. I haven't quite decided on that yet.

I then planned to float a 20mm toungue and groove floor with 20mm oak bonded to it and use this underneath,

http://www.rpginc.com/PDFs/Isolation...20profile).pdf

So is this a good plan?

Is there a better or maybe cheaper way of achieving the same result?

Any potential pitfalls to watch out for?

All suggestions and feedback welcome.

[Daniel Comport]

6 inches.... I assume you're going to use a double layer of 440x215x100mm blockwork?

You will save build time by simply laying them flat, and also give yourself a total of just over 8 inches instead of 6 for the same money.

[TornadoTed]

Originally Posted by Daniel Comport

6 inches.... I assume you're going to use a double layer of 440x215x100mm blockwork?

You will save build time by simply laying them flat, and also give yourself a total of just over 8 inches instead of 6 for the same money.

No only single layer of blockwork, the inner wall will be timber and plasterboard. The current live room has 6" single skin walls so it makes sense to mirror that on the new half.

[TornadoTed]

I'm trying to wrap my head around sealing an inside out wall!

I understand with a standard wall you put the plaster board on and mud the joins and backer rod/caulk the edges.

This isn't possible with an inside out room being built in an existing space as the plasterboard is the cavity side of the wall so you can't get to it.

Anyone got any details on sealing inside out walls?

[TornadoTed]

I figured I may get a better response with some picture describing what I mean.

I plan to build a room within a room from timber panels with plasterboard attached to the back. You can't get to the joins to mud them so I came up with the idea of machining a small groove where panels will join so that they can be sealed with backer rod and then caulk.

Anybody have any comments on if this is the best way to seal an inside out wall?

[Rod Gervais]

The concept is sound - you just need to flush out the details.....

You don't need the caulk between the studs..... you do though need to make sure that the routed joint is large enough to include backer rod as a part of the equation.

This has to marry not only the vertical joints - but the corners/floor/ceiling intersections as well.

If you don't include backer rod as a part of the equation the caulk joints will eventually develop cracks in the length of the joint - which will be a point of failure for the level of isolation.

3 sided caulk joints do not fare well.

If you can get it in your area "Big Stretch" caulk is the best I have ever seen and recommend it highly...

Big Stretch

Rod

[Rod Gervais]

One other comment here - and that is that I would not build the walls as a series of small panels - I would construct them in their entirety and then stand them up in place..... you will achieve higher levels of isolation with staggered joints than with a series of vertical joints..... you minimize the losses that way....

Rod

[DanDan]

It amazes me how a relatively normal product in one land can be unheard of in another. Resilient Channel in effect barely exists here, and that only recently. Most builders are astounded at the concept. Similarly Back Rod. Vital for the survival of caulked seals as Rod has explained many times. Never heard of it here.
But you should be OK TED http://www.amazon.co.uk/Everbuild-Jo.../dp/B004QHC4P2
DD

[Rod Gervais]

Big Stretch caulk on the UK site as well:

http://www.amazon.co.uk/s/ref=nb_sb_...tretch%20caulk

Rod

[TornadoTed]

Thanks for the advise Rod and thanks for the links Rod and Dan.

What size backer rod would you suggest?

[Rod Gervais]

The backer rod size is dependent on the width of the joint - the depth of the joint is dependent on the size of the backer rod.

For example: If you routed a 5/16" caulk joint you would need 3/8" backer rod - and the depth of the routed channel should be roughly 5/8" deep........ that would leave you with a caulk joint that was a 1/4" deep before tooling.......

BTY - "tooling" the caulk joint is am important part of the process to assure a good seal.... don't just fill the joint with caulk and then walk away......

As is the case with most things having to do with isolation - the devil is in the details....

Rod