JMH Property Maintenance » Cellars & Basements

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It cannot be over emphasised how important and critical it is to use correct techniques and materials when waterproofing a partial or full underground structure.

There are many tanking systems and techniques and many builders and related companies in the market place who will undertake work of this nature, often ending in an inadequate or poorly finished project. Structural waterproofing or tanking should not be confused with damp proofing where movement of moisture through vertical capillary action, (i.e. rising damp), is relatively easy to control with chemicals.

Although these factors are almost undoubtedly relative, in an underground situation the moisture is under hydrostatic pressure due to gravity. In many cases moisture appearing as damp patches can easily progress to water ingress - a much more serious and complicated problem to rectify.

Using control chemicals in these areas such as tanking slurry’s or silicone-based products is a viable remedial solution. The chemicals act as a waterproof barrier and stop water entering a structure by means of damming it. The negative sides of this type of system is the pressure it can be put under in extreme ground water drain conditions. For example, we all know how heavy a single bucket of water can be. Other factors are ultra violet light and chemical break down over prolonged periods.

With these factors considered the preferred technique is to actually allow the water into the building instead of trying to hold it back or dam it and manage the flow. (see images right - click to enlarge)

This is achieved by using drainage or ventilated tanking membranes. This system works in partnership with a drainage sump and pump, where the flow is collected and removed under pressure out of the structure to a safe and suitable drainage point usually at external ground level.