Technical Guidance
5.2/01
In-Situ Concrete Suspended Ground Floors
(December 2008) (First issue)
Question:
Question:
a) Where an in-situ concrete suspended ground floor is laid on a DPM, should the DPM be dressed up the side and over the slab (sketch A) or cut off at the bottom (sketch B)?
a) Where an in-situ concrete suspended ground floor is laid on a DPM, should the DPM be dressed up the side and over the slab (sketch A) or cut off at the bottom (sketch B)?
b) Is it necessary to provide a DPC between the top of the slab and the masonry inner leaf?
b) Is it necessary to provide a DPC between the top of the slab and the masonry inner leaf?
Considerations:
Cutting the DPM off would leave the slab exposed to water, which may collect at the bottom of the cavity. This could cause dampness in the home.
Answer:
a) The dpm should be dressed up the side and over the slab (see sketch A). The DPM should be pulled taut so that it does not bulge and tend to form a ledge on which mortar could build up.
b) A separate dpc is not required between the top of the slab and the inner leaf masonry where the DPM has been dressed up the side and over the slab.
