High water tables around Toronto Homes

High water tables around Toronto HomesDo Waterproofing Paints Work?

When you think about it carefully, we usually waterproof things from the outside. That’s as much true for garments, as it is for leaks on roofs. Engineers understand that it’s futile trying to stop seepage through a crankcase joint. Yet some in the basement-waterproofing industry keep insisting that basement walls are an exception to the rule.

Why Basements Leak

Underground spaces leak when two conditions are true:

  • There is groundwater backed outside of them, and
  •  Hydrostatic pressure forces a way into them, via:
  1.  The material of which they are constructed, OR
  2. Cracks and openings through this material, OR
  3. A combination of these two defects working together


These conditions are endemic in most spaces above ground. The difference with basements is the groundwater that lies around them. Contractors should adjust for this when building below ground level. The fundamental problem is that they often simply don’t as most of the time they apply the minimum waterproofing standards allowed by law during construction.

The Right Way to Avoid the Problem

When rain falls to the ground a certain amount of it inevitably pools. The earth absorbs the water. After that, gravity takes over and forces it gradually further underground. This happens faster in recently disturbed earth around the outside of basements. When it reaches the undisturbed level it starts backing up. There’s little we can do to stop this once it starts. However builders can install management systems, such as a weeping tile system, assuming they know how.

First and foremost, they are supposed to waterproof the outside basement walls with membranes that prevent the groundwater finding a way through the construction material – as well as any cracks and opening caused by subsequent ground movement. Most stop there, because they’re not thinking about hydrostatic pressure.

Waterproofing contractor in Toronto applying waterproofing membreane

This is the outcome of gravity bearing down on the column of water-laden earth that still backs up behind the water-proofing membrane. This can be sufficiently powerful to find a way through the slightest imperfection, filter through the building material and pour down the inside basement wall.

There is usually only one way to stop this, and that’s with an underground drainage system along the bottom of the basement wall outside and/or by applying an industrial grade waterproofing membrane along the outside of the foundation wall.. With minor leaks and cracks, the job and sometimes he handles from the inside, by repairing the foundation crack. Many homeowners are tempted to try water-proofing paint instead. While this does have its moments there are a number of limitations.

What Waterproofing Paint is For

Although “water-proofing” is something of a misnomer because the paint does not last forever, it does have some usefulness when applied to raw concrete when it can sink in and be absorbed. Under these conditions, it may be able to repel creeping damp for a few years. However it is no match whatsoever against determined hydrostatic pressure, which will easily work it’s way past any sort of paint sealant you apply on your basement walls.

It is also useless when applied to previously sealed or painted walls because its adhesive properties depend on absorption. Many a homeowner has paid to have it applied during the dry season, only to see it fail soon after the first heavy rain. In conclusion, the product is designed for repelling dampness, not for waterproofing against moisture flowing through your basement wall.

If you have any questions about a leak or damp problem in your basement, feel free to call us at 416-622-7000 or contact us via our web form.  We offer a 100% free Estimate and Inspection of your foundation.



The following two tabs change content below.


Waterproofing & Foundation Specialists at Nusite Contractors Ltd
As a family-owned waterproofing and foundation repair business with over 30 years of experience in Toronto, we are proud of our work and stand by it with a full warranty. We’re a service company, working for you. We make sure our customers understand the entire building and repair process, and ensure that our work is done properly and made to last.

Latest posts by Nusite (see all)