When it comes to waterproofing a basement there is more than 1 way to "skin a cat", but if you ask us we’ll tell you there are ways to waterproof a basement that are better than others.

We’ll list some of the most common waterproofing systems below and share our thoughts on each.

Cheapest. Least effective. Band-aid fix.

The concrete used to build your basement walls may seem like an impenetrable watertight material but it can actually absorb water rather easily due to it being quite porous.

For this reason we do not recommend sealing concrete.

If you seal the wall the moisture will be trapped in the concrete with nowhere to escape causing premature concrete failure and mold growth. 

While sealing basement walls from the inside can often play a crucial role in how waterproof your basement is, using this method will not be sufficient in solving your issue.

Sealing the wall and not addressing drainage, weeping tile issues will cause water to build up on the outside, freeze and thaw will cause structural damage.


Injections work by drilling holes adjacent to and angled into the crack in the foundation.

Injection ports are then placed in these holes.  These will act as a delivery method to inject the crack.  The crack is then sealed from the inside with hydraulic cement or epoxy.  The injection material could be an epoxy resin or a polyurethane foam.  The chemical mixture inserted into the crack will react and expand, filling the entire width and depth of the crack.  The dirt on the exterior of the foundation wall holds in the injection material allowing the crack to be filled.

Problems with injections

If your foundation wall already has an exterior membrane there will be no dirt to hold in the injection and allow the crack to fill.  Without the resistance (dirt) it won’t expand and fill the crack.  Most newer houses less than 25 years old have a builder's grade membrane such as the brown delta membrane.

Likely, the reason for the new crack or existing crack has started to leak is because the weeping tile is failing.  (40-60 year lifespan depending on soil type)

If the weeping tile is failing and you have injected the crack and not deal with the exterior pressure and frost another crack will appear and eventually structural damage will occur to the wall until the root of the problem has been fixed. 

More expensive. More effective. Not suitable for all homes.

First, a quick definition of these terms:

Interior drainage is the process of collecting water that gets into your basement and funneling it towards a sump pump for removal.

This does not address water and pressure from the outside walls from the freeze and thaw.

Sump pumps are powered machines that pump water from the lowest points of your home out of your house.

Typically, if you have a weeping tile system and do not have a sump pump the water from your weeping tile drains to your sanitary sewer.

NOTE: As of 2017, sump pumps are required by the Ontario Building Code so all new homes built since then will have a sump pump installed. (1)

Using these 2 together can be an effective solution for some homes and some situations.

While this basement waterproofing system is more effective than sealing foundation walls alone, it’s not a complete basement waterproofing solution.

If the weeping tile system on the exterior is no longer functional the soil and foundation will remain saturated causing extreme pressure.  The water will freeze causing walls to crack and eventually bow inwards.  Water will make its way to the interior system washing dirt away from under the footing causing footings to shift and break.

Most effective. Most expensive. Your safest bet.

Sealing foundation walls from the inside won’t fix the root of problem and cause others, which leads to costly underpinning and bowing wall repairs. 

And while yes, interior drainage and sump pumps can be effective for collecting and removing water that makes its way into your basement.  It doesn’t address structural issues that will occur.

The best method for basement waterproofing is to make sure water is expelled and drained away from your footing leaving no water to build up and enter your foundation. 

This is can only be done by exterior basement foundation waterproofing by digging around the outside of your foundation to expose the foundation and footings making repairs such as:

  • Structural foundation repairs; underpinning and bowing walls (depending how long you have waited or tried other attempts of band-aid fixes (i.e injections, interior waterproofing where frost is an issue)
  • Covering the walls with Platon membrane
  • Platon is a rugged, dimpled high density polyethylene waterproof membrane that keeps foundations and flooring dry. Platon creates an impermeable vapour and air gap barrier, blocking moisture and allowing concrete to breathe.
  • A working footing drain is a must
  • Clear stone must be placed over the weeping tile drain and over the footing against the base of the platon typically 16-24 inches

Exterior waterproofing is the most effective out of the 3 described so far, however a combination is often needed when access is not possible outside.

Contact us anytime to discuss your needs and we’ll be happy to inspect your property and provide a full report and customized recommendation.


1 - https://www.buildingcode.online/1051.html