well im about to knock dow our outside (built off the side of our kitchen) laundry and build it in.I plan on reusing the slab and frame up from there but the only prob is that the slab is at the same level as the ground outside and i can't get away with raising it due to the flat roof of the kitchen being only 2500 off ground level and this will flow on2 the laundry roof.Anyway im worried that rain water may lap the botton plate slightly should i ues treated timber for this or will i have 2 raise the slab above ground level?