DPM under concrete when shed will have bearers sat on their own DPM

[Dave Robinson]

I'm about to pour a slab for a 6m x 3m shed. Planning on at least a 4-6" slab (3.5m^3 - I'm buying the beers for a few mates!) as the shed will have a tiled roof & a few hefty machines, but the ground underneath is very, very solid. The shed will have a base sat upon 3" treated bearers, which I intend to wrap the underside of with DPM & leave gaps between bearers for under-base ventilation. Is it probably unnecessary to install a DPM under the slab itself before I go ahead with the pour?

 

[r896neo]

No go with a dpm. It will stop your slab drying out too quickly and result in a much stronger better result. This is especially valid at this Tim of year