On Mon, 26 Oct 2009 20:44:03 -0400, aemeijers wrote:

hr(bob) wrote:
On Oct 26, 6:24 pm, Bubba Bubbs wrote:
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.

Seehttp://picasaweb.google.com/bubbabubbs/20091025_firewall#539703986542...

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.

Seehttp://picasaweb.google.com/bubbabubbs/20091025_firewall#539704011995...

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

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.

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.

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.