On 29 Dec 2005 12:00:06 -0800, "michigan_t"
wrote:

Hi,

I just moved into a new house that has a huge attached garage. The rear
area of the garage
(apprx 700 ft^2) already has piping in the floor to heat that area.
The previous owner never got
around to finishing this workshop area, and this is now my #1 priority.

I have already added outlets every 10 feet or so, including 220
circuits for air compressor
and welder. (i do some metalworking as well...) I just insulated the
walls with R13 with the
vapor barrier backing, and now I am wondering what to put on next.
sheetrock, or osb???

The wall between the house and this back area of the garage is already
insulated and drywalled,
and I am wondering if i need to continue drywall all the way around for
fire protection
(since it is an attached garage, if it burns down, the whole house
could go up???)

Another point is that i am planning on using a small woodburner in
there to heat the area,
plus heat up the glycol that i will be pumping into the floor.) I
wouldn't be so concerned
about fire safety except for this point.

I would prefer to do OSB for cost and ease of hanging anything
anywhere, and I have
read the several other posts about this topic, but there hasn't been
much discussion
about osb vs. drywall from a fire safety point of view.

Also, is there any code requirements about what to use in an attached
garage?

Any help would be appreciated.

About 3 years ago I insulated and sheathed the inside of my shop with
OSB, using 2 layers of3" Styrofoam underneath for insulation with a
vapor barrier of 6 mil underneath that. My rationale for the OSB vs
dry wall was durability and moisture resistance. I finished the seams
of the OSB using drywall mesh and joint compound. in the styro foam
seams I used spray foam to seal/bond them together. The end result
was a very weather tight inside that appeared to be drywall, but
wouldn't "dent" or "puncture" if you accidentally rammed it with
something. The shop had metal siding (pole barn) 24'x36' 12' ft eaves
with two 10'x10' roll up doors and a regular size door entry with a
insulated storm door. The roll ups were also insulated, replacing the
original sliding single door which was impossible to get a good
weather seal on during the winter. The ceiling was prepared in a
similar way except no drywall compound was used. Before beginning the
insulation job I removed all of the existing light and power wiring
and would reinstall surface mount conduit after the installation of
the insulation. I finished the floor with Pittsburgh Paints Epoxy
paint to finish the interior upgrade. I was switching from T12x48"
dual fluorescent fixtures to T12 x 96" dual fixtures and was in the
process of laying out the best points to hang the fixtures for the
best use of the light and was awakened the following morning by
dampened THUD! sounds not unlike what a pile driver produces,
including the feel of the thud through the ground and I was inside my
home on the second floor.

The mystery sounds turned out to be my oxy/gas, and propane tanks
exploding inside my shop. The single power plug I had remaining had
been plugged into a drillmaster 14.4v drill battery charger the night
before and had evidently caught fire, catching the OSB, Styrofoam and
everything else on fire. When I discovered it the walls were still
standing however the fiberglass skylights in the roof had burned
through (all six of them) and were "boiling" out dense black smoke. I
knew then that it was too late and everything was toast at that point.
Luckily my shop was a detached building and was 10' from the house at
the closest point, it did however severely blister the house paint in
that area. I had welders, plasma cutters, router duplicators, three 5
hp air compressors I had just built on 60 gallon tanks that had never
even been powered up yet, couple of shopsmiths, table saw, and bunches
of hand tools and lots of handscrews and bar clamps, last but not
least, there was about 25000 board feet of 4-5" thick black walnut
slabs I had "stickered" and had been air drying for 1 1/2 plus years
in a loft that covered half of the shop. I am about ten miles from
the closest fire station up on a fairly steep hill (ever see how SLOW
a fire truck full of water goes up a hill?!!)

The firefighters basically just caved in the metal shell when they got
there and soaked down the burnt debris inside left on the floor slab.
There was charred debris about 2 feet deep over the entire interior.

SO, having said all that, what do you think I might recommend for
interior sheathing? Is it OSB or Drywall? Needless to say I will
NEVER use OSB in an application like that again, unless the structure
has automatic fire sprinklers installed and there is a standby power
source in case utility power is lost for some reason. ( I am
convinced that the catalyst that started the drill charger burning was
a large power surge in the first place!) Interestingly enough the guy
from the power company was first on the scene I found out later, and
NOT the meter reader guy whom I would have recognized. I assumed he
was the fire Marshall who drove up in his own rig to get there first,
he didn't identify himself until the lead fireman asked him "who are
YOU?" he replied: "I work for the power company.." Otherwise I
might still think he was with the fire company in some sort of
capacity.

Yes, my house now has as will my new shop heavy duty surge suppression
installed in the distribution breaker box, along with a dual power
fire/smoke detection system that is all networked together, and I am
seriously considering overhead sprinklers for the shop at least. If I
go with a conventional metal sided pole barn the inside will use
fiberglass insulation and sheathing will be "green" drywall for
moisture resistance with Tyveck or similar house wrap as moisture
barrier next to the metal siding of the outside walls. I am seriously
considering a new wall system invented by Dow Chemical that uses a
4-6" foam core with wire mesh on both inside and outside walls that is
then sprayed with a high strength liquid concrete, similar to gunite.
Another possibility is to use standard concrete "Tilt-up" walls that
are cast in forms onsite.

One small ray of shining light in the whole mess was that the
stickered walnut in the shop loft was so thick that about 1/4 of it
will be salvaged. when the loft collapsed the walnut planks got
buried by everything else and given the thickness of the slabs only
burnt about 50% of the wood in the middle of the stack.

The short answer to your question is: My vote is for the drywall.
Good luck, best regards and happy new year, Joe.