What is your main concern when you’re thinking about the whole concept of having a basement? Is it the fear of dampness coming through the walls or even more severe leak? The biggest concerns of the great majority of our clients have something to do with the ground water and with the fact that the basement will most likely be exposed to ground water. I have to admit that this is natural and most genuine concern. Dealing with the ground water requires knowledge, it is definitely a challenge and underestimating it had had serious consequences in the past. As the water remains one of Four Elements it needs to be given attention of a proper magnitude.

How do we deal with ground water? How can we stand over our Lifetime Waterproofing Guarantee that we offer for our basements?

Every basement project is initially assessed in the context of its ground water conditions. The selection of the most appropriate waterproofing techniques is based on that assessment. For instance, if the water table is high we would recommend a combination of two or three independent waterproofing technologies used simultaneously on one basement. If the water table is lower than the formation level of the proposed basement one waterproofing technique is normally enough. Of course, this is not as simple as one need also to take under consideration possible yearly fluctuations of water table, basements on the slope require altogether different approach and dealing with the ground water during the construction stage is a science on its own.

The waterproofing systems that we use can be classified in three groups.

1. External membranes. These membranes are installed in a way that they wrap the whole structure of the basement forming one continuous seal. The membranes are based on bentonite which has a very interesting and useful property. It can expand up to 15 times its original size when exposed to contact with water. When the membranes are sandwiched between the basement walls and well compacted backfill material (or underpinning concrete) the expansion of the bentonite seals all possible entry points the water could get in.

2. Waterproof concrete. The reinforced concrete (RC) walls and base of the basement can be designed and built as a waterproof structure.

3. Internal cavity draining mats. These mats are installed on the internal faces of walls and floor of the basement. Their objective is to intercept any possible water seeping through the structure of the basement. The water is then collected into a sump and pumped out.

Using combinations of these techniques we have delivered basement projects in ground conditions with water table only 1 meter below the ground surface.
I hope this answers your questions in relation to ground water and gives you an insight on the second of the three most important design elements.

Back Next