John Sayers' Recording Studio Design Forum

Hello there
I just finnished framing out my room,which is 1'' away from ceiling joist and 1'' away from outer walls.
My problem now is what to use as a fire block without making a flanking path?
I have been searching the site but can't find a clear enough illustration of this ,also i have Rob's book but the way the drawings are i dont have the same set up on the top of walls.

My question is ,can i nail 1.5'' rockwool to the top of the outer wall and just extend the rockwool to the top of the new wall(barely touching) so that it block that 1'' space between the two walls?

How about if you provide us with a sketch of what you have?

One problem with just using the rock wool is that although it will stop the passage of fire itself - it will NOT stop the passage of hot gasses........ which can by themselves start a fire on the other side of it......

and if you have any experience with rockwool - you will know that t is a crumbly material - I have little hope of it holding to nail over any length of time........

Rod

_________________
Ignore the man behind the curtain........

I wont make this long,i know i know but i am lossing sleep over this.
Take a look at these pics Rob.

Let me know if this will work without creating a flanking path even if the rockwool is a little compresed?

First of all - if you want my help at least take the time to get my name right...........

Next - you should really keep your stuff in one thread - it is so much easier to track that way - much better than a zillion little one question threads.......

Now - to answer your question:

Where the joist run parallel to the walls - which would be the middle picture - that would be fine

If will not work in the bottom picture - if you compress it to that point it will create a flanking path........

Thin it out till it is just 1/8" thicker than the space and install it.........

Rod

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Ignore the man behind the curtain........

I can;t beleive i have been calling you Rob all this time .I'm sorry about that

Ok, the bottom picture that you said it wont work is because the inner ceiling joist frame is pused over a little too much on that side.
It really is suppose to be flushed with the top plate,we just didn't nail them in yet bcause i wasn't shure about the firestop.

1) So is that the reason you said it wouldn't work because it seem like it came over into the 1'' space between walls?
Because just like the middle picture it is supposed to have the same amount of space.

2) And let me make shure i fully understand ,your'e saying just shave the rockwool down to 5/8'' because the space between walls is 1'' and the rockwool is 1.5''?

3) Do you have any recommendations on how to attach the rockwool to the outer leaf top plate? Should i still use fire caulk or is the accoustic caulk fire rated enough?

Rod,i am sorry if i offended you it wasn't intentional.I can't pay you for the help you provided me so for.And is there a way to merge my post into one?

Please click to enlarge photo

Thanks

thin it down to just slightly over one inch - and pressure fit it in there - you should allow for fire caulk (the rockwool will stop the passage of the fire - but will not stop the passage of hot gases that can ignite the wood beyond it.

Anything below the bottom of the plates is a waste of money because it serves no real purpose........

If it is pressure fit it will stay in place - if you are nervous about it just pop a couple of finish nails into the plate and bend them back to hold it in place..........

Rod

_________________
Ignore the man behind the curtain........

Rod where am i putting the fire caulk?
Am i putting it on the side of the rockwool facing the outer leaf top plate almost like i am glueing it to the outer ceiling and top plate?

Also you said not to extend it pass the plate,which one are you talking about is it the top plate of the INNER WALLS?

Rake a look at pics,i have the carpenter guy to work for me today so i am trying to get it done while he is here.

Thanks

Rod,
Is this correct?
I am installing the fireblock before i put in the new ceiling joist on inner walls but the joist is going to be flush with the edge of the plate so it should be the same amount of contact.
I cut down the 1.5'' rockwool to just under 1''X 6'',and i extend it down between the wall JUST an inch or so below the inner wall first 2X4 TOP PLATE.
i DID NOT EXTEND IT DOWN TO THE SECOND ONE BECAUSE YOU SAID IT SERVES NO PURPOSE.

tAKE A LOOK AT WHAT I BEEN DOING,I''L STOP NOW UNTIL YOU REPLY TO MAKE SHURE I AM DOING IT CORRECT.

What are you guys using around your outlet and linght fixture boxes to make up for the hole in the leaf?
I saw someone used some kinda putty,is that enough? or should i use 2X4 to build little boxes around outlet boxes and caulk around it?

Where to get the putty from and what its called?

3M putty pads are excellent:

http://solutions.3m.com/wps/portal/3M/e ... 6W2S54F8gl

Another pad available here - performance will be the same as the 3M product:

http://www.esoundproof.com/Screens/Prod ... Packs.aspx

another - better pricing:

http://www.soundisolationstore.com/putt ... tlets.html

that should be enough sources to give you the idea - if you weant to shop price even further - just google "putty pads".

Rod

_________________
Ignore the man behind the curtain........

Rod
You didn't comment on the fireblocking pics,i assume that means i'm ok?

Also i started to build 2x boxes oround the outlets after i saw a few guys here recomended it.
But i am still gonna buy some putty to use around the outlets and switches in the live room since 1)the 2X boxes are difficult and 2)its only $25 for a pack of puty and i could use the time more wisely.
Also i showed a HVAC guy the silent boxes and he quipt with ''I DONT SEE WHY YOU CAN;T JUST MAKE THOSE OUT OF DUCT BOARD WITHOUT THE PLY?''


What u think about the putty in live room over 2X and also the Silencers?

AM I seeing that right ?" Do the outer walls pass by the inner walls without a fire block in the outer walls? You need a positive firestop.

The firecaulk can go either at the top or at the bottom - but it should span from wall frame to wall frame - it has to create a complete gas stop between the 2 walls.



Wel you could always tell him to shut the hell up and do what he's being paid for........

Or you could explain to him that although the duct board is pretty good for sound attenuation of fan and duct noise - but it is one hell of a lousy isolator for any of the other noise floating around - and we don't want outside noise entering the last point we have open right at the entrance of the air into the room.......

Nah - just tell him to shut the hell up and do what he's being paid to do.........

BTW - he is using polymer lined duct right - not the exposed fiberglass crap board?




I do not understand this question..........

Rod

_________________
Ignore the man behind the curtain........

Sorry Rod,
The last question was asking if since i already made some 2X4 boxes around the outlets in the control room and they are a little annoying to make can i just use the putty pads for all the outlets in the Live room and forgo the 2X4 BOXES .Or just take out the 2X4 boxes alltogather and use the putty pads?

As for the fireblocking, i just shave down the rockwool to a little under 1'' and fit them between the inner and outer leaf with fire caulk holding it in place.
I will take some more pics tomm and see if i can get better angle.

The HVAC guy is not doing the duct work i am.He is gonna install the unit when i am ready. I have to do most of the work myself budget is on the low side
Hvac guy was giving me some guidance and ideas about the size duct etc.

And i know i have read where you dont recomend using flex duct for long runs,but i dont know if i could do the other way.
Would i be losing any isolation from using flex duct for a 13'' run send and returns? they will all be up in the cieling joist and i would use flex duct to connect from silencer to my inner ceiling.

Hi,

Rod's already told you what to do, but I'll see if I can describe it in a different way.

I have a few minutes here so I will see if I can help you out.

The area you pointed at in your pictures is the right area, as long as by sealing between the plates the entire ceiling cavity is separated from the wall cavity.

Edit: I just looked at your picture again and I think you have to create your fire stop between the exterior plate and the ceiling framing, in other words, exactly where you pointed in the picture.

The general idea here is to use the mineral wool as backer rod. By this I mean stuff the wool between the exterior top plate and the interior top plate creating as flat a surface of mineral wool between these two plates as you can. Now cover the entire surface of the mineral wool that's exposed between the plates with the fire rated caulking, sealing in the entire space between the two plates. Make sure there is a good thick layer of caulking, and a couple of inches of mineral wool. Make sure to seal any other cracks that exist between the wall cavity and the ceiling cavity.

The reason to create this seal at the sill plates is because this is the easiest place to separate the two cavities.

The reasoning behind this is to compartmentalize each area, in case of a fire in a cavity between the walls or between the ceiling and roof. If a fire started in the wall cavity it would spread very quickly to any upper spaces due to the chimney effect.

Please ask for clarification if this is not clear, fire stopping is important to get right.

Steve

Ok, i just got finished running my electrical outlets and i use 14-2 wire,then i realized that i would need another ground conductor if i am going To do isolated ground.

So my question is how much i would be missing if i just went wiTHout the redundant ground?

Should i just redo THe outlets with something like 14-3 to get THE EXTRA CONDUCTOR OR WOULD I BE OK WITH 14-2 WIRES?