I have a garage with a bedroom behind it. The roof is conventionally framed (i.e. no truss rafters). I want to use the open attic space above the bedroom for storage. The ceiling joists are 12? O/C and sufficient to support the loads. I am aware that I must move the firewall which is fine. My question is how do I make the floor in the attic space a fire barrier. I can?t use the underside of the ceiling joists because it has penetrations for heating ducts into the bedroom. For storage all I need is ¾ or 1? plywood for the floor.
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First, welcome, seeing this is your first post. (I gotta lot of BS on my first post, so I try to be nice>)
Anyway, some ideas for your consideration
1. you can go with solder link fire stops on the ductwork (steel doors that drop shut across the duct when fire melts the solder in a gravity or spring loaded metal door)
2. 2 hours silicate treated firecode plywood for the floor. I don't know the retail cost of this stuff, but use it a lot myself as I can get it free at a company surplus wood lot that dismantles old commercial buildings. The joists will burn thru long before that stuff will burn.
3. 1/8 " cement board under ply. -- see # 2 about the joists.
conclusion, if it were me, I'd get out my big tin snips or shears and some 12 Ga galvanized (or heavier, I got lotsa 3/16 plate so would use that myself) and make me enough drop traps for the ductwork - then some chain and 63/37 lead/tin or even bithmus solder and thin copper strips to make the solder links for gravity firestops. You can also just use the 63/37 solder as a chain link, but a soldered together pair of wide thin copper strip is preferred 'cause it would catch the fire heat faster than just the solder itself and wont fail by itself every 40 years due to oxygen/crystalyization.
Why do you need a fire wall and what are you trying to slow the fire down from where to where?
I think that just the garage wall and possible the ceiling need to be fire resistant.
If I understand what you are doing..... cutting a hole in the fire wall from the garage above the ceiling level of the bedroom for storage ..... if you install a self closing fire door assembly and you don't store flammables, etc, I don't think the area above the bedroom needs a rated assembly. Sketch it up and talk to your local building official (they don't bite).
Norse
Thanks, I guess what I was looking for was a way to fire rate the floor of the attic so I could eliminate the wall between the garage and the bedroom attic.
I'll see if the building department has the answer.