Hi, the problem with joint compound is the fact that it is NOT
intended for wet use. Adding it to your PC slab mix weakens the
slab overall. The whole wall board industry is geared to protecting
the board from water which is why "green" or "blue" board is specially
made for bathrooms, kitchen, wet areas. It is not supposed to get wet,
it swells, and the paper sandwich exterior will attract mold.
( that hideous black mold ? -the drywall industry is now advertising
the paper-free product, people fear mold for good reason)
In PC use, having free bags of joint compound to use is nice, but
keep it to interior plasters, and non wet areas. Just because you have
it is not a good enough reason to use it, especially outside where
rains, & weather will be working against you.
Cement " backer board " ( aka commercial compressed papercrete) is used
for baths, tiling, shower areas, because wall board with the gypsum
component is weak, and will fail in a wet environs.
my 3 cents
Charmaine Taylor Publishing
Monster SALE on Books & Videos
http://www.dirtcheapbuilder.com/mobovisa.html
Tel: 1-707-441-1632 Eureka, Calif.
