John Sayers' Recording Studio Design Forum Archive

spesh99 wrote:

Paulus87 wrote:

spesh99 wrote:Been a few months off - something came up in the house and quite literally sapped my funds. However back on it now.

Based on advice up this thread I now understand the limited value in even contemplating trying to float the floor. And John - based on your advice I will be recycling the rubber matting to separate the wall plates from the concrete block - accepting that they will be screwed down - so technically will short circuit" the isolation - but a limited amount - and I am benefiting from this whole studio being in the corner of a garden. The walls have to be secured somehow right???

See diagram.

Thoughts gratefully received.

Hi,

Yes bolt your sole plates for each frame down firmly into the slab. The neoprene strip is really there to compensate for any unevenness between the timber and the concrete - it fills little gaps to ensure a better air tight seal.

I don't understand your simple diagram though - your outer leaf has the drywall inside the cavity but shows nothing on the outside of the studs, obviously you can't leave it open to the elements so what are you going to put there to weather proof the whole structure? Just a word of advice, it would be better to put all your mass on the outside face of the studs rather than inside the cavity, it will increase your air gap, avoid a three leaf assembly and be simpler to build.

Also, make sure you fill the cavity entirely with low density fluffy fibreglass insulation.

Have you figured out your roof/ceiling assembly yet?


Paul

Thanks Paul
No - in truth I have not worked the roof out.
Sorry the diagram is very simple it was more to illustrate the plates / neoprene and drywall. You are very right externally it wont be left like this.
I will most likely (once the voids are insulated), OSB board the whole exterior, add a membrane and then cladd it a yet to be determined cut of wood.

So something like (out to in)

Cladding
Membrane
OSB
Stud Wall (insulated)
Drywall
air gap
Stud Wall (insulated)
drywall
GG
drywall



Roof i need to work out - complicated
more by the fact the shed wont be perfectly square (long story and I accept complicated but doesn't really change how i build it in terms of insulation etc.

Roof advice very welcome indeed.

You’re creating a triple leaf system, which is not good.

It should be like this:

Mass - insulated air gap - mass

E.g. something like this:

Cladding
Membrane
Osb
Studs
Insulated air gap
Studs
Osb
Drywall

What you currently have is:

Mass - air gap - mass - air gap - mass

Which will lower your overall transmission loss, especially in the low end which is really where it counts.


The roof and ceiling depends on a few things; firstly you should decide if you want to construct a warm roof or a cold roof. If cold roof it needs to be vented without compromising your isolation, which I can show you how to do. If warm roof then you do not need vents so it is easier to maintain isolation. It’s also more efficient.

Paul

So.

I have a need to build my outer wall on a single course of bricks. This is to help minimise any risk of water ingress.

I have a couple of questions re your last post John if you don't mind.

Cladding
Membrane
Osb
Studs
Insulated air gap
Studs
Osb
Drywall

Can I confirm if there is a need for any drywall on the inside of the outer wall AND/OR the outside of the inner wall (i.e the air gap).

I attach an image - the points i am referring to is where the star is. Does this look right?



Secondly.

I still remain confused about the floor - but just float 3x2's 400mm apart on an additional piece of neoprene / rubber matting excess. What grade insulation should i place in the floor cavity?
I am definitely getting myself confused about the need to float a floor or not.
I am not aiming for perfection - just "good" in truth. Constrained by budget, but benefiting from the fact the whole thing is in the garden.

spesh99 wrote:So.

I have a need to build my outer wall on a single course of bricks. This is to help minimise any risk of water ingress.

I have a couple of questions re your last post John if you don't mind.


Cladding
Membrane
Osb
Studs
air gap
Insulated air gap
Studs
Osb
Drywall


Can I confirm if there is a need for any drywall on the inside of the outer wall AND/OR the outside of the inner wall (i.e the air gap).

I attach an image - the points i am referring to is where the star is. Does this look right?



Secondly.

I still remain confused about the floor - but just float 3x2's 400mm apart on an additional piece of neoprene / rubber matting excess. What grade insulation should i place in the floor cavity?
I am definitely getting myself confused about the need to float a floor or not.
I am not aiming for perfection - just "good" in truth. Constrained by budget, but benefiting from the fact the whole thing is in the garden.

No, do not put drywall in the air gap.

Otherwise you will end up with:

Cladding
Membrane
Osb
Studs/air gap
drywall
Insulated air gap
drywall
Studs/air gap
Osb
Drywall

That is a 4 leaf system... even worse than a 3 leaf system.

If you need the extra isolation and therefore the extra mass then you can put extra layers of drywall (or whatever mass you like) but those extra layers must be on the same side of the studs and the existing layers i.e. leave only one large insulated air gap in the total assembly.

The extra layers can also be installed in the stud bays (between the studs) pressed up right against the inside face of the existing layers, if it's easier to install e.g. on an outer leaf since you can't expose drywall to the elements.

Personally, I see little point in floating a timber framed floor on top of an existing concrete slab - the slab is far more dense and damped by the earth, you are not going to beat it in terms of isolation, it is already enough.

If you need to build a timber framed floor for some other reason then I would fill the voids between the joists with kiln dried sand, all the way to the top of the joists and then clad with floor grade 22mm plywood/osb. Therefore, I would not use insulation inside the floor.

But speaking in general, regarding insulation inside any cavity - always use the cheap fluffy low density fibre glass, there is no need to use anything else as it will not yield a better result. If for thermal reasons you need to use something more efficient then use Rockwool inside the actual stud bays and then fill the gap between the frames with fibreglass.

Paul

Thank you so much. Kiln dried sand is GENIUS! Didn't think of it at all. I think because of the height of my neighbours garden i ought to raise the floor. Its not ideal - but its safest to eliminate moisture.

I have already dug a channel around my slab and filled it with gravel to help any run off from next door (naturally higher).

Paul, Could you recommend any insulation worth looking at - or literally just own brand loft stuff?
I am quite surprised the more rigid board type stuff doesn't perform any better? Why is this?

spesh99 wrote:Paul, Could you recommend any insulation worth looking at - or literally just own brand loft stuff?
I am quite surprised the more rigid board type stuff doesn't perform any better? Why is this?

Is this for inside your double leaf walls/ceiling/roof?

Yes the cheapest fluffy stuff you can find will be more than sufficient. The soundproofing is due to the mass layers on the wall, not the insulation - anything that can get through the mass layers (which have far more surface density than the insulation) will not magically be stopped by the low density insulation. The insulation in the cavity is to absorb the resonance of the chamber and damp the mass layers. Therefore a denser insulation is not only a waste of money but also has no benefit.

Paul

John Sayers wrote:Yes, use a layer of neoprene for your inner walls. Use the stuff you mentioned for playroom floors assurance invalidité- use a Stanley knife to cut it into 4" wide strips.

You'll find the rubber mounted floor wonderful to walk on and drummers tell me their kit sounds great on it.

cheers
john

Seems like a good method to me. Anyway, thank you very much for sending us this information.