John Sayers' Recording Studio Design Forum Archive

Hi all

I was wondering if I could get some help on the design for a firestop in a double frame wall. Looking through Rods book theres some good detail there - but as his overall wall design is different to mine, so I wanted to check my thought process. Have done a search but didnt come across the detail I was looking for.

Pic 1 shows how I think it should be constructed - but as I am going to have my ceiling joists attaching to the inner room frame, I wasnt sure how to incorporate these into the design.

Pic 2 shows one idea, but I am concerned that there isnt enough contact between joist and frame top plate

Pic 3 shows another idea but I am concerned this will comprimise isolation, as the plasterboard firestop is touching the outer frame and inner ceiling.

I'm wondering if I have to accept some iso loss for safety - or am I totally off the mark here?

The pics below assume that the 'outer' wall is actually a corridor wall - but if the outer wall in the pics was actually another room, would the same mineral wool and caulk detail be used on both frames?

Any advise would be great. Many thanks all.

BTW - You can see more detail about my overall build on this link.

http://www.johnlsayers.com/phpBB2/viewtopic.php?t=8013

Cheers
Dave

Pic 2 shows one idea, but I am concerned that there isnt enough contact between joist and frame top plate

i'd go with #2. Ceiling joist do not need to rest on the full width of the top plate, there is a calculation that exist (wich i don't know ) that will tell you according to the load and span of the ceiling joists what would be the minimal support lenght needed. But resting your ceiling joist on, say 2 1/2 " of the top plate then use the 1" left to "rest" the firestop is a safe bet IMHO, but nevertheless verifying with a structural engineer would be your best option.

#3 is a no go as far as i'm concern.

My city is allowing me to use gypsum to bridge the gap, but to leave a gap and then stuff it with insulation (Rockwool in my case -- Thermafiber SAFB).

I cover this on page 75 of my monster thread.

Be sure to read further down on the page to see the code section that applies in my jurisdiction. It may or may not apply in your situation, but it may give you a place to start.

--Keith

Thanks to both of you for your replies! Much appreciated.

Dave

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