no problem as long as water doesn't come in contact.mdf and water dont
mix.i wouldn't use them in the kitchen.i would also prime all 4
sides.also hd carries mdf shelving which is 11-1/2" wide i believe,you
could get two 5" pieces out of one board.a little more expensive but a
lot easier to handle and rip on the ts.also wear a dust mask this stuff
is very dusty.hth