What Bruce said except use 5/8" rather than 1/2" only costs about $.08 a
square foot more, gives the code level fire protection you want. A 30' x
8' wall in fire code rated rock is only an extra $20

Bruce L. Bergman wrote:
On 11 May 2006 11:13:15 -0700, wrote:


I have built a two story 30' x 40' stick framed shop. The main floor
is separated into two sections, one which I plan to insulate, houses my
machine tools, the other I use for welding, car repair etc. Niether
area is panelled yet and I tying to decide how I should go about it.
My current idea for the welding area is to cover the lower 48" with
cement board ($30 for a 4 X 8 sheet) and the remainder with Aspenite
covered in flame retardent paint ($11 for a 4 x 8 sheet). I do not
want to use drywall because I do not want to tape it and it will get
all bashed up. Does anyone have an opinion on the flame retardent
paint?


If you want true fireproofing, there's nothing better than good old
gypsum drywall. Use 5/8" installed properly, with fire rated doors
and closers and no unprotected penetrations, gets you a two hour rated
firewall. Unless you are WAY out in the sticks, the Fire Department
can get there before it spreads.

Rather than spend a lot of money on the cement board I'd drywall the
entire room in plain 1/2", tape the joints - it doesn't have to be
three coats all sanded down and pretty, but I would still mud over the
screws and one coat over the joints, a fast sand to knock the high
spots down, and now you are fireproof. Hit it with one heavy coat of
PVA Drywall Primer/Sealer so any liquids that make it through don't
soak in and stain or wreck the drywall.

And then for armor against abuse panel over the top of the drywall
walls with 1/4" or better plywood or hardboard. Screw it to the studs
like the drywall, finish the corners with simple pine molding, and
coat with the fire retardant paint to keep little sparks from
sticking. And if you manage to dent it, you change a sheet.

And if anyone ever decides to build a new bigger shop and turn the
old shop into a guest house, it's mostly done. Just strip the
plywood, patch the nail holes, and give the joints a second coat. Or
fill the big divots and hit it with the spray texture gun, the spatter
texture hides a lot of little sins.

-- Bruce --