Why a course of bricks under stud walls in garage conversion? (Solved)

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We are converting an attached single skin garage. The separate stud walls are to be built with air gap/insulation/soundbloc plasterboard etc to make a room within a room. The room will be used as a music room/home cinema/studio etc.

Our investigations show the concrete slab is nice & thick & has damp layer under it. The building reg has asked for a course of bricks under all stud walls with a dpm laid on the floor & lapped over the bricks & then build the stud wall on the brick layer. Is there a way around that? The builder thinks we should be able to lay dpm on floor, then build stud walls directly off the concrete floor.

I would like to avoid the BR solution as this will kill our sound isolation plan for the room. I would appreciate any tips & advice please

Cheers

Fib
 
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If the wall is single-skin, the inspector will be concerned about rain penetration running down the inside of the brick and pooling on the floor (which it might in heavy rain and with no ventilation to dry it off). The usual practice is to put a cavity tray at the bottom so that any penetrating damp is kept away from the studwork, hence the two courses of brick he has asked for.
 
If the wall is single-skin, the inspector will be concerned about rain penetration running down the inside of the brick and pooling on the floor (which it might in heavy rain and with no ventilation to dry it off). The usual practice is to put a cavity tray at the bottom so that any penetrating damp is kept away from the studwork, hence the two courses of brick he has asked for.
Thank you Tony. Is there any alternative I can maybe suggest to him? Maybe paint or line the the inside of bricks with waterproof/vapour proof layer etc etc.....
 
When we did similar to a detached garage we started by painting the floor with a liquid dpm that went 18" up the walls. The stud walls wer built on top of 4" wide 1" neoprene strip to isolate the walls from the slab.no fixings went into the floor and the cube structure of the studding did not contact the external walls.
2 types of rockwool (rw 4&3 from memory) filled the studding with an air gap and two layers of plasterboard, overlapped by 1/2 a sheet to avoid joints near joints.

The whole idea is to build a self contained room in a room.

Then a polythene dpm on the slab, rockwool rw2 on the floor and a glued together floor that floats on the row and does not touch the walls.
 
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Thanks Tigercubrider for your tips & pointers. Our rough plan is quite similar, except that our walls are inside out so two layers of staggered plasterboard, vapour layer & some insulation will be on the outside. The stud walls will be built on the floor & then erected into position. Then the insulation between studs will become available for acoustic treatment of the room.

I do need to sort this 'course of bricks' conundrum with BR though.
 
When we did similar to a detached garage we started by painting the floor with a liquid dpm that went 18" up the walls. The stud walls wer built on top of 4" wide 1" neoprene strip to isolate the walls from the slab........
Hi Tigercubrider

Presumably this method using neoprene approved by Building regulation - would you have any links for this so I can provide to my inspector? Thanks very much

Fib
 
https://www.soundonsound.com/techniques/practical-studio-design-part5

dunno about regs but it is standard practice in most studios.
My mate had an Andy Munro studio designed that basically sat on rubber pads and truck springs. ( for work not home use!)

Ah...the venerable Mr Munro....We were looking for a set of main monitors designed by him but they are rather big for our 35 sq metre space.:)

I am presently investigating and awaiting information on http://www.kabuildingproducts.co.uk/tanking_slurry.html (with latex addition), and the tech support seem to think this will run past the building reg. I may even add a layer of neoprene for good measure so help calm their nerves.

Regards
 
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Thanks Tigercubrider....I am never sure how much these things isolate unless we know the exact mass & the percentage compression of the strip.

On a separate note, building control have accepted the solution (tanking slurry) mentioned in my earlier post instead of the bricks under all stud walls. Long live our sound isolation!

Hope this is helpful to someone fighting a similar battle.

Cheers

Fib
 

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