Damp Proofing Floor Slabs

To comply with building regulations, floor slabs are usually poured on top of a damp-proof membrane (DPM) to protect against damp rising up from the ground (rising damp). However, there are two main situations where a DPM may need to be installed on top of a concrete slab:

• Where the slab was laid without a DPM (e.g. old buildings) or where the DPM has been damaged (e.g. torn during construction). In such situations it is usually easier and more economical to find a way of installing a new DPM on top of the slab rather than digging up the slab and pouring a new slab on top of a DPM.
• Where a new concrete slab has been poured correctly with a DPM underneath, but where a moisture-sensitive floor finish (e.g. wooden floor) needs to be laid on top before the constructional moisture from the slab has had time to escape. In such cases, applying a new DPM on top of the slab can allow the floor finish to be applied the same day  – reducing delays to following trades and allowing projects to be completed faster.

A number of products available from Safeguard are suitable for applying on top of concrete slabs to form a DPM.

Liquid-applied or “slurry” damp-proof membranes

Drybase Liquid-Applied DPM, Drybase ECS Epoxy Floor Coating, and many products from the Vandex range including Vandex BB75 and Vandex Unimortar 2 can be applied directly on to damp floors to form a damp-proof barrier. These products are relatively simple to apply, although significant surface preparation work is usually required.

Oldroyd Xs Slimline Cavity Drainage Membrane

Oldroyd Xs can be loose-laid directly onto a concrete slab (or certain other floor types – e.g. flagstones). In most cases, no surface preparation is required. Many types of flooring can then be laid on top – e.g. particle board, laminate flooring, solid-wood flooring, screeds, etc…

Where Oldroyd Xs is lapped up the wall, the special “X” pattern of grooves in Oldroyd Xs allows moisture to escape from under the membrane – whilst the membrane itself remains water and vapour impermeable.

Radon Protection

Drybase Liquid-Applied DPM and Oldroyd Xs are suitable for use when protecting floor slabs against radon gas. Call our technical department on 01403 210204 or fill in our technical enquiry form for details about protecting against radon.