Waterproofing new floor slabs

It is possible to construct floor slabs from waterproof concrete complying with BS 8007. However to achieve this grade, a considerable amount of extra steel reinforcing is required, greatly increasing the cost of the slab.

An alternative approach is to use standard concrete of the required strength in conjunction with a coating or membrane to protect the slab from water ingress. Safeguard offer two options for waterproofing new floor slabs. Other options are available for the waterproofing of existing floor slabs.

Vandex Dry Sprinkle Method

Vandex Super powder is sprinkled onto the wet concrete slab after the initial set. It is then power-trowelled into the surface, imparting waterproof properties to the slab. A summary of the dry sprinkle method of application is given below:

The concrete is poured, vibrated, and levelled as usual.
The concrete is allowed to reach its initial set – generally when the concrete has enough strength to carry the weight of a man without leaving footprints deeper than 2 mm. It is essential that excess water collecting in puddles on the concrete surface is removed prior to the application of Vandex Super.
Vandex Super powder is applied to the slab through a sieve at a rate of 1.2 kg per square metre.
As soon as the dry sprinkle application has taken place the finishing operation can begin and the slab can be trowelled to the specified finish. It is essential that the Vandex Super powder is worked into the surface either by power trowel or by hand trowel. If a non-skid surface is required, one pass of the power trowel will be enough. If a steel-trowelled surface is required two or three passes will usually be required.
For maximum effectiveness, the treated slab should be protected against evaporation for a minimum of five days whilst curing takes place.

Oldroyd Xs Waterproofing Membrane

Oldroyd Xs is a tough polypropylene membrane embossed with an ‘X’ pattern of grooves. To provide a waterproof barrier, the Oldroyd Xs membrane is simply rolled out under the position of the proposed floor slab before the steels are put in place. The joints are then double-sealed using Oldroyd Double Sided Tape and Oldroyd Overseal Tape. The slab is then poured in the usual way. When installed in conjunction with other appropriate measures such as radon sumps, this option also offers protection against ground gases and soil contaminants.

Oldroyd Xs is manufactured from much thicker plastic than standard damp-proofing membranes so is much more resistant to damage on site – e.g. damage caused by rebars laid on top.