To prevent water ingress into a structure, an impervious membrane should always be applied as a Damp Proof Membrane (or DPM) above or below a ground floor slab. 

Whilst you can apply DPMs to either a concrete binding under the slab or internally to the top of the slab, you should give consideration to applying the DPM to the top of the slab, as this way, the installation and moisture sensitive internal finishes are protected from any residual moisture remaining in the concrete. All commonly encountered insulation materials are compatible for use with DPMs. 

Flexi-seal is a high performance DPM, and has a colour-coded QC (quality control system) and also excellent flexibility which makes it especially suited to modular floor construction, for example beam and block floors or pre-cast planks. 

Seal-sheet is also a popular choice because it can be applied quickly due it its zero drying time. It also has factory-controlled thickness so has the additional benefit of self-sealing minor damage and imperfections. Due to its elasticity, suspended floors such as beam and block constructions are also easily protected with seal-sheet. 

Liquid-membrane is a liquid epoxy coating, applied in two-coats. It is well suited as a finished surface membrane (for example below levelling compounds, bonded areas, plant rooms or under raised access floors) as it has excellent substrate adhesion and a Class 1 Surface Spread of Flame fire rating.

Flexi-seal coating is based on polyurethane technology. It consists two coats, and is a seamless and fully bonded liquid-applied waterproof membrane. Flexi-seal has an innovative curing process - which draws moisture from the air to form a highly flexible but also highly durable barrier to both water and water vapour. It is typically used where you require a high performance tanking system.

When specifying or designing Type A structures (as per BS8102:1990) the product is capable of providing the levels of protection required for grades 1,2,3 & 4 basements – when applied correctly of course.