John Sayers' Recording Studio Design Forum Archive

Hi Andre,

Sorry for the delay in response to your question.

Doesn't that connect the two walls though, thus defeating the purpose of having space between the two walls?

While it may look like it is connected in the photo the trick is to keep them isolated from one another. I'm assuming your book has arrived now so you should be able to see the detailed diagram in there but do let us know if it's still not clear.

I'll take a crack at your other questions too and I'm sure Stuart will chime in if further clarification is needed.

a) Do you think it would be better to add a layer or two of gyproc between #2 and #3?
b) Also, is pink fibreglass fine instead of Safe n' Sound rock wool for the ceiling?
c) Would it make sense to replace the last layer of ⅝" gyproc (#9) by a ½" Gyproc?

a) adding beef up definitely will not hurt. It will definitely help with impact noise from the above space and by doing this you are increasing the mass of the other side of your MSM layer which will increase your overall isolation. Don't forget to seal every hole in every joist bay too - you will be going through a lot of acoustical caulk and backer rod!
b) I used it in my last build and it worked just fine. I recall others recommending it was perfectly fine not to mention significantly cheaper. Just be sure not to have it so thick that it ends up connected your two leafs together - you want to make sure it remains the Spring in your MSM.
c) I wouldn't. Having the extra mass of the 5/8" will help with the lower frequencies which are the ones that are always harder to contain.

Cheers!

Andy.

Thanks Andy,

Do you know also what is the point of adding all that backer Rod? Is it for acoustical reasons?
And about the "temporary" nails Rod mentions in his book to hold the ceiling layers…
does he mean that we should remove them? If so, how is the thing suppose to hold in place?
My contractor would prefer to just leave them in place or at least the last one in place.

Thanks

Andre

Hi Andre,

The purpose of the backer rod is to ensure a two point connection between the caulk and the surface - this is they way that it is designed to work. A three point connection will not work acoustically as far as I am aware. If you search here on the forum you will find multiple discussions on the theory behind this.

The temporary nails can be left in place. Ultimately the weight is supported by the cleats that you add around the bottom perimeter (attached to the joists).

Cheers!

Andy

Stuart or anyone,

Can you tell me what you mean by "cleats"? English is my second language so a google image would be great.

It would be better if you could add more mass by cutting strips of 5/8" drywall to fit between the studs on the wall cavity side of that drywall, holding it in place with cleats, and sealing around the edges with acoustic caulk.

Andre

Stuart or anyone,

Can you tell me what you mean by "cleats"? English is my second language so a google image would be great.

Cleats are just small strips of wood nailed sideways into the joists, and they support the drywall. Nothing complicated! If you search the forum for "cleats", you should probably find photos somewhere, but there's nothing magical about them: A simple piece of wood, several inches long (or maybe longer) maybe a 1/2" to 1" wide, nailed sideways to the faces of the joists, with the drywall resting on top.

(But considering your nationality, I won't confuse you by talking about French cleats, which are different... French cleats are also useful in studios for mounting absorption panels and other treatment devices to the studio wall, but not the same as ordinary cleats that you use for holding drywall in place....)



- Stuart -

Great! The cleats are in.

In regards to the existing ceiling, I read in Rod's book that I can put pink Fibreglass instead of Roxul (see #2 below).
But after doing part of that ceiling and comparing it with the Safe n' Sound in the walls, I'm shaving second doubts about that.
The Fibreglass doesn't seem near as effective.

I know Rod is top, but can someone still confirm this is ok?
Also, should I put Safe n' Sound or pink Fibreglass in the new ceiling? (see layer #4 below)

Thanks

=-=-=-
Here is what I'm planning:
1-Add two layers of ⅝" drywall between joists (partly done)
2-Put one layer of pink fibreglass (partly done)
3- Space
4-Build a new stud structure resting on the new walls on the side with Roxul or fibreglass?
5-MDF
6-Gyproc ⅝"
test the noise level, then if needed, add:
7-Green Glue
8-Gyproc ⅝"

Can someone tell me if this is ok?

The contractor in my absence today attached the new interior wall stud structure to the joists .
It seems to me that it shouldn't touch the existing joists and the new ceiling only should rest on the new wall, no?

You are correct sir - the new framing should not be attached to the existing joists for the approach you had described. This would significantly affect your isolation. I would ask him to fix it.

Good luck and be glad that you caught it!

Agree with Andy... No mechanical contact at all between inner and outer.


- Stuart -

Ok thanks! They're just gonna remove the pads so then the wall won't connect to the joists.

In his book on page 104, Rod says he prefers a single "super door" than two standard solid-core doors. Do you know why? What's better?

And why not just add a layer of MDF or Plywood for the two solid doors?
(I think I'll avoid the lead sheet though. I hear this is not too good for health.)

(I think I'll avoid the lead sheet though. I hear this is not too good for health.)

As long as you don't eat your door, you should be fine. Lead is only a problem if it gets into your stomach or lungs somehow, so provided that you don't chew on the lead sheeting while you are installing it, and take reasonable precautions which you should be taking anyway, with or without lead, then I wouldn't be too worried. By "reasonable precautions" I mean: wearing gloves and eye protection all the time while building, washing your hands when you leave the work area, and using a simple respirator (mask) while doing anything that generates dust. You should ALWAYS do that, even of there is no lead around!

Here's some advice from people who know:

http://www.britishlead.co.uk/health-and-safety.htm




- Stuart -

Ok. Would you know why Rod prefers a single Super door with lead than two solid wood door? Is it because it gives better isolation?

And why not put lead/plywood on both doors? Would that make the doors too heavy for the frame?

Ok. So for my ceiling at this point, I have these layers below from top to bottom.
We can't hear tv or voices anymore, but I can still hear steps, impacts.
So what is best way to continue from here?

One or two layers of Gypse with green glue?
Any better idea for impacts?

-Gypse ⅝"
-Gypse ⅝"
-Roxul
-Fibreglass
-Space
-New 2" x 4" ceiling with Roxul
-MDF

Thanks

I have these layers below from top to bottom.

Are you sure those are ordered from bottom to top? That implies that you are walking on drywall up above!

Any better idea for impacts?

For impact noise, it is better to damp it as much as possible at the source, such as with a carpet on the floor, or thick plywood subfloor. You might also want to decouple the ceiling below with resilient channel, or with RSIC clips and hat channel.


- Stuart -

Hi Stuart,

Well, just above the two layers of gypse, I have a laminated wood floor and the usual plywood floor.
We also added another layer of gypse below the MDF by now.

But what do you mean by adding Resilient or Hat channels?
I thought this was not necessary or recommended since
I already have some space between the lower and upper ceiling.

And how could I reduce impact noise at the source?
I read about rubber being good and I know we don't want carpet in our living room,
but I wouldn't mind some temporary rugs for when I record

So this is what I have so far.
-Laminated wood floor
-Plywood
-Gypse ⅝" (cut layers places between joist)
-Gypse ⅝" (cut layers places between joist)
-Roxul
-Fibreglass
Space
-New 2" x 4" ceiling with Roxul
-MDF
-Gypse ⅝"
-(Could add another layer of Gypse ⅝" with Green Glue eventually)

Thanks