basement waterproofing

Did you know that the city of Toronto sits on top of a labyrinth like maze of ancient rivers and sewer systems that have long been forgotten about?  While there are many reasons your Toronto basement might be leaking water, in some areas, rising water tables could be the problem.  While the water table below your home may be several meters below your foundation, that doesn’t mean that it won’t cause water problems in your basement.  Below explains what a water table is and how it can effect your home.

A water table – sometimes also referred to as a groundwater table – is the upper level of accumulated water that has collected on the saturated or impermeable surface below it. Groundwater tends to level out just like the water in your bath or swimming pool. That’s why it’s called a table by the experts, because the tops of tables are usually smooth too.

High water table in Toronto from underground rivers and streams

Two Types of Water Tables

Geologists speak of two kinds of water tables, namely perched ones and true ones. True tables are those prevailing in an area. They represent the average water height, plus / minus the prevailing season in terms of wet or dry. However water doesn’t always seep down consistently. Factors that affect water penetration include:

  • The degree of existing saturation
  • The permeability of the strata
  • The presence of impermeable rock.

Groundwater may perch higher at some points than others as a result of this phenomenon. Think of this as a step-change, or as if there’s a thick book laying on your desk or table.

Implications for Building Basements

Homeowners watching their new basement being excavated should not necessarily be content when the earth comes out dry. That’s because water could rise up during the rainy season if their home is in a low-lying area, and exert hydrostatic pressure on the walls resulting in leaks and cracks in your home’s foundation.

This is especially probable if their house is built on clay, or if they have to excavate through hard rock or shale to create space for the basement. That’s because excessive rain could cause water to perch around it temporarily, inevitably increasing the risk of mould-inducing dampness.

Artificial Causes

Basement contractors dig out a larger area than they require, so they can work on both sides of the walls as they damp or waterproof them. When they are finished, they backfill the spaces on the outside of the basement, usually with the same material they previously excavated.

This creates a leaky fill especially if they’re using rock or shale that water filters through more rapidly that the original underlying surface can absorb. This in turn creates a dam of wet material right around the outside basement walls. This can stand for days or even weeks in winter. Just imagine the hydrostatic pressure if you filled the space with water, and you’ll have a good idea of the consequences.

Prevention is Better Than Cure

If you are looking for a home and are concerned about water problems, or you currently have water problems in your basement, you need to consider a four-pronged strategy to knock this problem on the head. Ignore this advice at your peril. You could be inviting a high repair bill in the future.

  • Avoid building/buying your house – or add a basement – in a low-lying area that’s surrounded by high ground or where water drains to naturally.  Water will use gravity and  find the path of least resistance when searching for a low lying area, which could be that new home you’re eyeing.


  • Do install french drains / weeping tiles around the outside walls at the lowest point, to drain groundwater away before it causes damage.


  • Do not allow the contractor to backfill with loose material.  Be sure the backfill is replaced properly or you could be creating a swimming pool around your foundation. If necessary, import something more suitable.


  • Do everything you can to prevent water from finding its way from the surface to the bottom of your outside basement walls in the first place.

In these ways it is usually possible to manage groundwater effectively. Ignoring a water leaks in your basement for too long can lead to expensive repairs and health concerns from mold later on down the line if left untreated.

image courtesy of Environment Canada



If you walk in mist or fog and your clothing becomes wet, you feel a sensation of dampness on your skin – unless of course you are wearing a water-resistant garment. In pelting rain the water will force itself past the fibers, and start pouring down your arms and legs.  That’s why sailors aboard ships wear sou’westers, not scotch-guarded pullovers.

A similar principle applies to homes and basements. Damp-proofing is a lightweight treatment that helps prevent the moisture in the soil from penetrating through a basement wall or floor. However, if there’s a possibility of underground water damming up from time to time, then water-proofing is the only practical solution.

Why Is That?

The difference is a thing called hydrostatic pressure. When you were at school your teachers probably tried to explain that the pressure exerted by a column of water is equally exerted in all directions. This means that the weight of damp earth outside your basement applies an incredible force to its retaining walls, and can force the moisture in through any cracks as if it’s a pump.

This same pressure ensures that most basement walls and floors eventually fracture (although this may sometimes present itself as mere hairline cracking). As the ground-water begins to find a way through the fractures more and more water takes its place, creating a steady trickle if nothing is done to impede the flow. Under these circumstances traditional damp-proofing methods are useless, for reasons mentioned below.

Why Damp-Proofing Fails

Builders customarily apply an asphalt-tar solution to any outside wall that’s below ground level. This is to meet Section 406 of the International Residential Code that specifies this as the bare minimum. While this may be adequate in dry, hot areas, it seldom suffices in Canada, where expansion and contraction between winter and summer seasons causes it to crack (especially over existing cracks in walls and floors).

Why Water-Proofing is More Successful

Water-proofing on the other hand is a material that’s mainly made from natural rubber, which means that it’s environmentally friendly. Moreover, as your basement flexes and cracks open and closed again, genuine water-proofing stretches and shrinks in harmony, so that it keeps on doing its job.

The Extra Cost  is Worth It

The budget-end of basement builders sometimes maintains that damp-proofing is equally good – and cheaper too. But then it’s not their problem when it fails, because they’re not responsible for the power of nature, and where you chose to build your home. When that happens there’s only really one solution. And that’s to remove every square inch of cheap damp-proofing, and water-proof your basement properly from scratch.

In Ontario, You Really Don’t Have Much of a Choice

Ontario’s prevailing climate with longer, usually frozen winters, and temperate summers in the south is an open invitation for basement walls and floors to crack. If you are building a new basement this means that you need a specialist to water-proof it for you. On the other hand, if you’re already experiencing leaks and dampness because of previous substandard damp-proofing, then the same logic applies again. If you’re experiencing water problems in your basement and are thinking about a solution, waterproofing methods is simply the better choice as a long term solution.


Water is a mighty powerful and persistent thing. It’s carved out canyons and has flooded huge cities. Allow it drip for long enough and it will punch a hole through granite. When it comes to your basement – if there’s a way for water to find it’s through, trust me, it will discover it and you’ll soon have a leaking basement  problem.

That’s why so many of Toronto’s basements suffer from some form of basement water problem. Causes of this can range from leaking water wells and cracked walls, to porous and cracked floors. Left untended, basement leaks can lead to all kinds of associated problems, ranging from mold and mildew, declining property values, to a family with an entire floor of their home that is unhealthy and unusable.

Sump pump installed in Toronto home

Two Options

There are only two solutions to a leaky basement. The first is to stop the water getting in. The second is to manage it (more about this later). Any competent car mechanic will confirm that the only way to stop an oil leak is at its source. The same applies to basements (choosing a mechanic and a contractor should be taken with equal care).

Unfortunately, when basement water-proofing fails from the interior, there’s no easy way to stop it because the source is on the far side of a brick/concrete wall, or under a concrete foundation deep below the ground. This makes accumulating the water in a hollow called a sump usually the first course of action. When it’s accumulated, you can lead it away with an electric pump.

Sump Pumps

A sump pump is not unlike a water-feature pump in principle, in that it’s connected to an electricity supply, but always under water so it never develops an airlock. The sump is equally simple. It’s just a hollow you could squeeze a beach ball into, and covered over with a lid so everything looks neat and tidy.

The system is controlled by a float that’s not unlike the one in your bathroom toilet (at least in principle again). When the water reaches a set level, a switch turns on the pump for as long as necessary to control the water in the sump. By far the larger challenge is leading the leaking water to the sump in the first place. But that’s a subject for another article.

Do I Need a Sump Pump?

You need a sump pump if there’s an accumulation of water in your basement at any time of year. They’re not all that expensive. Besides, if you ignore the damp, mold could become the least of your problems. Your basement den or bedroom could become permanently uninhabitable. Imagine what that would do to your property valuation, and the value of what is probably the biggest investment you’ll ever make.

A Permanent Solution

If you have permanent bronchial problems, you could be living in a damp environment. If your basement is permanently damp, then that’s a sign of a deeper-seated problem too. Once you have successfully stabilized your situation with a sump pump, you really should call in a registered and experienced basement waterproofing expert. They will advise you on a longer term solution that retains the integrity of your home.


As a basement waterproofing company, we often get calls for leaks in the basement during heavy rain fall.  Often times,  cracks and leaks around  a worn and decaying window well is the source for these water problems in the basement..

There are a variety of window well designs available. Some are deep, and closed in on top for safety. Others are shallow and open to the elements. All have the same basic purpose. That’s to admit light through a window in a basement wall.  The well around the window is meant to prevent without water to accumulate or leak past the window pane and down the basement wall.

window well in Toronto basement

Ways to Keep Window Well Water Out

  • Keep Surface Water Away – If water pools around the barrier wall it’s eventually going to find a way through. Make sure the ground slopes away from the well on all three sides, and that there’s no water splashing down directly from the roof. Check the outer side of the wall for any cracks or leaks, and seal suspect joints. If made from brick and mortar, waterproof it from the outside right down to the foundation.


  • Manage the Rain – If your window is entirely below ground level (or just about) then you may like to install a gently sloping roof to keep your basement snug and dry. However the glass will require cleaning regularly and it will no longer be possible to admit fresh air through the window. For that reason, many people prefer to leave their window wells open to the sky. In that case, it’s necessary to install a french drain to lead water that enters the well away.


  • Belts and Braces – As sure as the Good Lord created chickens, every window well has its day when it floods. This is because the roof above might take damage in a storm, or the french drain blocks because it hasn’t been kept clear. In either case, the window well will soon be brimming full of water, and the window becomes your only defense against a flood.

This is why it’s equally important to install a window that’s one hundred per cent waterproof in itself, and to inspect the seals regularly for any wear or damage. Of course, everything will be for naught if someone left the window open before the storm arrived. There’s nothing more capable of ruining your day than a waterfall cascading down into a basement.

creating a decorative garden in window well

The Intelligent Solution

Window wells are an essential feature of any basement – especially if you’re using it as living space – because it admits air and light. If well designed, it also acts as an alternative exit route which some basement might be required by law, depending on your area. By definition it’s also a window opening below the level of the ground. This is a recipe for disaster if the homeowner neglects the window well and lets it fall into decay.

A basement flood is not just another inconvenient insurance claim. There may be no structural damage cover by your insurance company when there’s evidence of neglect. This is definitely not something to attend to on a lazy Sunday afternoon when you finally get round to it.If you’re having some water problems around your window well, or think it might be time to call someone in to take a look at it, give us a call.


Foundation problems are pretty common in Toronto, especially in older homes closer to Lake Ontario.  Toronto is a city with a high water level table, meaning many areas experience chronic problems in their basements due to ground water swelling up underneath the foundation.

The earth’s not static beneath your home’s foundations. In fact, it’s a dynamic living thing that reacts to moisture welling up, or coming down as rain. As it absorbs water, it expands, and as it dries out again, it contracts. This translates to your foundation moving up and down during the change of seasons.

While concrete foundations are reinforced and seldom fracture, the brick, mortar and concrete structures standing on them are only hardened to the extent the builders considered necessary.  Fortunately, they give off early warning signals like cracking and splitting when underlying problems start to develop. Depending on the severity of the cause, you could try to fix it yourself, or ignore it at your peril.

Warning Signs

a stairstep crack in a cinderblock basement wall

Where there’s sudden, catastrophic erosion after a severe flood, the problem may display as a seriously tilting house that could finally collapse. Where the problem is chronic due to fundamental soil conditions, the indications are likely to be more subtle and could include the following:

  • Step-cracks in brick walls that spread out from structurally weak points like openings and corners. These typically open wide in drought, and close again when the earth below is moist and expands. The power of heaving soil is mighty and it’s pointless trying to patch them. You have to tackle the foundation problem that’s causing them first.


  • Movement in the walls may also display as sticking doors and windows during rainy periods, and correspondingly loose ones when it’s dry. Here, it’s often possible to apply a flexible seal to keep out the draught. Once again, this is just a temporary solution.


  • A more serious problem is indicated when a concrete floor starts to crack, either on ground level or down in the basement. If moisture starts finding its way through then a crack is likely caused by a ground-water problem. If not, there’s a likelihood of poorly-compacted earth beneath.

Tackle the Problem

Subsiding foundations and cracking walls are not a job the average homeowner should tackle themselves. The work is highly technical, especially because it’s seldom possible to inspect the root cause of the problem without an experienced foundation contractor employing special detention tools. Moreover, exposing foundations is hard work that requires specialized equipment.

Seek Independent Advice First

Arrange to have your home inspected by a registered, competent structural foundation contractor. Get a few opinions to be sure you’re going with the right solution as it foundation repairs are usually a fairly big job. Sometimes, your problem turns out minor and you can just learn to live with it. At other times, a trained expert can provide a detailed specification of what needs to be done (and inspect the job as it goes along too).

Appoint a Foundation Repair Specialist

Again, remedial foundation work is hardly the job for the average contractor (or worse still the local handyman). You need to find someone who can repair the underlying problems, fix the consequences like cracked walls, get rid of damp problems and ensuing mold, and finally, provide an effective guarantee against a return of the problem.  If you’re in Toronto, you’ve probably seen stories like this one where inexperienced and low priced contractors were hired to do a complex job, resulting in dangerous and expensive results.

If you have questions about your foundation and would like an expert, no obligation opinion, contact us here.