This type of treatment is required where external ground levels are higher than internal floor levels where walls are totally earth retaining, for example, within basements and cellars, subterranean vaulted areas that may be completely enclosed by earth or where adjacent structures or properties are constructed at different levels. The theory of structural waterproofing is to provide a water impervious, dry, decorative surface internally, retaining moisture or dampness or indeed free running water within the adjacent ground area. This type of structural waterproofing is often required where adjacent ground levels are slightly higher than internal floor levels and excavation or lowering of these levels is not practically possible.
Waterproof rendering can also be used in other situations where penetrating dampness cannot be avoided.
Multi-coat renders are cementitious renders modified with chemical additives and applied to the structure in several layers. Cementitious coatings are pre-mixed compounds supplied in powder form. Once mixed with water on site, the waterproofing slurry is then applied in one or two coats to a previously applied base coat, which can then be covered by a further render coat creating a 'sandwich' effect.
Cavity Membrane System:
The membrane system is a complete range of products which can be used together to solve many of today's problems in both new and old construction.
The membrane system can easily deal with progressive ground water conditions where basements are liable to flooding, or indeed where simple dampness, contamination or salting problems are prevalent.
Where the system is being installed to cope with capillary held moisture, this can be done without the need for elaborate drainage facilities. However when dealing with free water, or if there is a risk of water damage, then a suitable drainage facility must be incorporated within the system. This could e channels cut into the floor, soakaways, sumps, and mechanical pumps.
Depending upon the system installed, options are available with regards to how the walls/floors can be finished. With wall applications the membrane, once installed, can be plastered or prepared in readiness for a dry lining system. Floor membranes, once installed, can be finished with either a screed or a 'floating' timber floor.