Q: Attached garage firewall - how to seal?


1966 ranch house in Denver Metro, Colorado. (I am not the original owner.) The attached garage does have a firewall (5/8 drywall) that separates it from the house. Two issues:
1. About 8-9 ft above garage floor is a hatch in the firewall; the hatch allows access from the garage to the attic above the house.
See http://picasaweb.google.com/bubbabubbs/20091025_firewall#5397039865428189714
The hatch is, essentially, a 2ftx2ft opening in the drywall/firewall. The 2'x2' piece of drywall is not even attched with any hinges, it's just put in place to cover the opening and is fastened with four nails. Naturally, there is a little bit of space inbetween, so I would like to seal that space - basically, seal off that whole hatch. The idea is to ensure a good fire-resistant seal between the garage and the attic. (Going forward, I won't use the hatch; there is another hatch in the hallway inside the house for attic access.)
My question: what kind of sealant should I use to seal the spaces between the hatch "square" and the firewall. Would any kind of fire resistant caulk do the job? Or is there some kind of tape I'm supposed to use?
2. The firewall/drywall doesn't go all the way down to the garage floor. Rather, it ends about 3 inches above the garage floor.
See http://picasaweb.google.com/bubbabubbs/20091025_firewall#5397040119956909026
Also, the drywall protrudes by about 3-4 inches from the wall on which it is mounted - you can see how the bottom edge of the drywall is a few inches away from the bottom concrete part of the wall. The space behind the drywall is hollow (some 2-by-4s, I guess), so I would like to seal off the bottom in order to create a fireproof seal, but also to prevent moisture/insect/debris intrusion. But that area is a bit awkward to work around.
My question: what is the best way to seal off that space? Can I use the expanding foam sealant that somes in an aerosol can?
Thanks Bubba
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Can't comment on legality of what you are proposing, but the expanding foam to seal the lower edge seems reasonable, but you will have to have something to keep the foam up in the wall and not falling down onto the garage floor while it is setting. Isn't there any insulation nbetween the garage wall and the inside of the house presumably that is what is on the other side of the wall? I would not use the extremely expandng foam on the outside chance that it would expand so much that it would blow out the wall, either into the garage or into the inside room.
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hr(bob) snipped-for-privacy@att.net wrote:

At work, they seal penetrations through firewalls with fire-stop caulk. Sorta rubbery when dry, and red. For OP- I wouldn't lose a lot of sleep over it- even if firewall is all the way up to roof deck, once the roofing material lights off over garage, whole roof is gonna burn anyway. I'd just get a panel of the 5/8 firestop rock larger than the hole by a foot in every direction, and screw it over the hole and forget it. That way, if you ever need access, it is still there, but you have the tighter fire break you wanted. You can even trim out the outside edge of this overlay panel with u-channel of a tight fit, if you want it to look pretty.
-- aem sends...
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On Mon, 26 Oct 2009 20:44:03 -0400, aemeijers wrote:

There is a fire-stop foam you can use on the drywall bottom. That is a very unprofessional cut job on it and it is not normally hung to the floor. It is very unusual for it to be past the top of the cement foundation as the joist box is usually resting inside the foundation edge. Personally, I would cut the excess off and put on a nice edging on it. That would be cut with a Dewalt drywall cutout tool and a guidepoint bit.
Mike D.
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Just mud and paper tape to seal the hatch...The bottom I would rip down a PT 2X? to fit REAL snug between the drywall and the concrete...Slide/tap the 2X into the space between the drywall and concrete untill it is somewhat straight and/or level and screw the drywall to the 2X every foot or so..No need to attach to concrete...Let it float..It will be fine...Trim off any drywall that extends past the new 2X...Screw a 5/8 strip of drywall to the bottom..May have to do it by hand with a screwdriver if drill/driver can't get under it...Get some vinyl cornerbead and staple or glue it on with 3M Drywall Adhesive and mud with joint compound...I wouldn't try to nail regular cornerbead to it or you might break the drywall.......HTH....1966 is the same year my ranch was built too...LOL...
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I took a short course on firestops etc, a long, long, long time ago. What I remember was that:
drywall/no tape/no mud = very poor firestop
drywall +tape + mud = good firestop
At work, they used some sort of quick setting ceramic cement to seal around cables penetrating walls but they were meeting a tougher code than residential.
Keep in mind that in residential, it's mostly "fire-slow-down", not really "fire-stop".
Regards -J
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