basement waterproofing

wet basements richmond hillOh dear. It’s winter, and the wet basement smells damp again! In fact, it’s getting to the point where you don’t want to go down there any more – but you have to, in order to check the furnace and clean up some of those water leaks from time to time. Here in Toronto, many of the older homes suffer from chronic wet basements and it’s not only annoying, but removes a whole level of a home that could be a perfectly good living space.

While some basement water problems are beyond a homeowners control, like rising water tables and hydrostatic water pressure on the foundation, there are several things you can do to try and keep your basement as dry as possible.

Let’s Take a Walk Outside First

Basements get wet due to rainwater intruding through the ground around them, especially when gutters and downpipes discharge large quantities in a small area. Inspect your water drainage system all the way to the discharge gullies. If the water is pooling above or near your basement, you can bet your last dollar its filtering further down too.

About the Window Wells …

Do you find water pooling under or running down nearby a basement window? Well then, you’re probably looking directly at the problem. Digging out and replacing an old window well can be quiet a mission. But you could probably make the problem disappear by attaching a plastic bubble for less than $50, excluding labor, sealant and a few screws.

Not Solved Yet? Let’s “Crack” the Problem

Water is a mighty curious thing. When it spots a crack in a basement wall from outside, it’s just has to pay a visit to see the view from within. If the cracks are less than two millimeters wide you could have a go with silicone – or hydraulic cement if the gap is bigger. Just make sure you rake out everything that’s loose, and do the job when the gap is dry and dust-free too.  This can be a tricky fix, if it looks like anything other than a hairline crack, you may want to call a basement waterproofing contractor to come and seal it properly.

On to More Serious Matters

It can happen that the integrity of your basement wall has failed in places, and that the water’s permeating directly through it. The correct solution is to expose it on the outside, and water-proof it properly so the problem goes away. If you’re between jobs (or a little cash-strapped maybe) you could apply a sealant on the inside. Rest assured though, the problem will return.

Finishing Off the Job

After you’ve stopped the water penetrating (at least for now) you need to get rid of the remaining moisture, unless you like musty smells and mould. Your sure-fired winner is a heavy duty energy-rated dehumidifier. But don’t go cheap, or you’ll soon be buying another one.

Still Not Fixed?

If your wet basement problem won’t go away (or soon returns) you need to face up to the fact that it’s beyond your scope of work and time. There are a variety of options ranging from weeping tiles to sump pumps. The work is technically advanced. It’s time to call in a basement waterproofing expert to ensure a long term fix to your water problems.


Use foil to find source of leak basement torontoIt’s easy to know a basement’s leaking when there’s water running down the walls, or pooling on the floor. It can be more difficult to find the source of the problem though. As a waterproofing contractor in Toronto, we are often called in to find the source of a basement leak after the homeowner has tried unsuccessfully to find the source.  The following advice is pitched at the level of the novice, or DIY family handyman. Anything more than that and you’re better off to call in a professional waterproofing contractor, before the inconvenience turns to permanent damage.

  1. Check the Ceiling First – If you spot any ceiling stains this must be where you look first – before you blame the walls for water running down them (or the floor because of pooling water). There is no substitute for a comprehensive inspection. If there’s a false ceiling under the concrete slab or rafters, you must remove this in its entirety so you can look properly.


  1. Inspect the Plumbing – Water has an amazing ability to travel almost anywhere because it’s so slippery. In fact it’s even been known to travel uphill for a short distance because of capillary action. Check every joint on your plumbing and appliances thoroughly. Be aware that metal failure does eventually follow on from vibration.


  1. Spot the Efflorescence – Don’t stress, this is just the white power that results from interaction between water, and bricks or concrete. Brush away the powder (it’s harmless although you might like to wear protection), then tape a piece of cooking-foil across the centre of the area. Remove the foil a day later and examine it. If there’s moisture where it pressed against the wall you’ve got a basement leak. If not, the efflorescence is caused by humidity in the air.


  1. Look for Wall Cracks – Where these exist (and there’s water seeping through them) you’ll generally spot them easily because liquid follows gravity, and runs straight down a smooth wall. If not, abandon your cursory search and divide the area into an imaginary grid. Start by looking at the top, then work your way down progressively to the floor.


  1. Check for Peeling Paint – The hydrostatic pressure of water weeping through a wall is powerful enough to lift the paint off. While you’re inspecting for cracks, also check for any sign of mould, because this will only grow where a wall is damp.


  1. Finally, Examine the Floor – If you can’t find a leaky ceiling or damp walls, then the water laying on the floor is welling through it on account of hydrostatic pressure from below. Tell-tale clues of the location of this include lifting floor tiles or a squelchy floor covering. If there’s anything standing on the spot that’s made of metal, it will have started rusting too.

What to do About It?

Now that you’ve found the source of the water leak, your next step should be to do something about it. That’s because over time, water seeping through a building degrades the structure permanently. Before you attempt to fix a leak at the point that it appears, remember that the only way to do this properly is at the source. And if that source is on the outside of a buried basement wall, you may be just a little way out of your depth.  A qualified waterproofing contractor can conduct an inspection, and lay out several possible solutions for you to examine.



scarborough waterprrofingThe short answer is sometimes, but in many cases, no.

Nusite has been in the waterproofing business in Toronto for a long time, I can’t remember how many failed interior basement waterproofing jobs I’ve been asked to fix, and how much money has been wasted in that way (although I’m sure it’s a big number in both cases). It’s not that the work itself was bad, it was just the wrong solution to applied to the job.  The truth is that the only sure-fire way to plug a leak is at its source, and that’s the honest truth.

However there are a few methods that could help you manage the problem from the inside. I’ll tell you about them on the basis that there’s always a reason why something seems inexpensive – but often isn’t in the long run.

Things that Might Work

The correct way to waterproof a basement is from the outside. The logic is the same as putting a roof on top of a house, as opposed to trying to waterproof the ceilings from underneath. Why’s that? The pressure of the water pooling on the ceiling boards will work its way through them, and dislodge the paint from inside. We call that hydrostatic pressure in the water-proofing industry

However even a basement that’s well waterproofed from the outside will still leak if cracks develop in the walls or floor. The same can happen if a plumber drills a hole through through the wall. In that case it’s perfectly feasible to seal the gaps with a polyurethane caulk – or epoxy filler if the openings are wider than one eighth inch.

If the moisture is permeating through the fabric of the building itself, no amount of epoxy or polyurethane (or any other product in my experience) is going to do much good for any length of time. That’s because of hydrostatic pressure, once again.

True, you could install a weeping tile around the internal perimeter of the basement and pump the accumulated water away with an automated sump pump. You could even cover everything nicely with a plastic sheet or panel. But you still haven’t waterproofed your basement.

Toronto waterproofing contractor exterior dig

What Should Work

Concrete, cement and bricks are made from natural products found in the earth. And water seeps through earth in no time at all. The only way to stop it leaching through your basement walls and floors is to prevent it from getting there in the first place. This implies four necessary steps:

  • Lay down a waterproof membrane before you cast the foundations and the floor.


  • Water-proof the outside of the foundations and the walls as they go up.


  • Install an external weeping tile system to lead any ground moisture away.


  • Manage your surrounding home and garden so that rainwater flows away.
installing exterior weeping tile in Toronto home

What Definitely Doesn’t Work

I’ve also seen a great many of the things that should work fail, especially when they’re performed by someone who doesn’t have alot of experience with foundation waterproofing.

The Best Advice of All

If you have a chronic leaky basement, and there doesn’t seem to be an obvious solution.  Have a waterproofing contractor come in and give an inspection.  A good waterproofing company will bring in the necessary tools to find the real source of the leak and can give you an accurate estimate of what it will take to repair the problem.  That doesn’t mean you have to do it, but you will know whether or not it’s a waste of time trying to stop the leak from the interior of your basement.


water leaking through basement floor

Water Leaking Through Basement Floor

While you shouldn’t rule out a home with a wet basement, you do need to do some further investigation before going ahead with a purchase agreement.  Here at Nusite, we’ve been a part of hundreds of home inspections in Toronto over the years.  Many times we get called in when a home inspector or buyers agent discovers a potential problem and recommends a waterproofing contractor come in a give an assessment.

Since basements are basically a hole in  the ground, kind of like an inground swimming pool, and rainwater will naturally flow to low lying areas, basements are bound to have some sort of water problems. Sometimes the seller of the home you buy may not even know of them. At other times, they may try and conceal them. At best you have a repair job ahead of you. At worst, you could be in a legal battle trying to recoup the cost of repairing your basement.

Along with seeking the advice of a  traditional home inspector, if you suspect water problems in the basement, your safest bet is to have a waterproofing contractor inspect the basement before you buy the house. After all, you wouldn’t purchase a second-hand car without asking an expert for an opinion, and having the vehicle tested too. It makes sense to apply the same logic when buying a second-hand home. The waterproofer’s report shouldn’t cost you an arm or a leg either, but could potentially save you from tens of thousands of dollars in home repairs.

Things to Look Out For

Insist on doing the inspection without the seller or their agent hovering nearby.  Alarm bells should start ringing in your head the moment you spot any of the following:

  •  The characteristic musty smell of damp or mould. If you find it in a basement, there’s bound to be moisture down there somewhere too.
  •   Water staining anywhere on the ceiling, floor and walls. Make sure you bottom out on the cause, and find out if it’s still happening.
  •   The white powder the experts call efflorescence. Water leaves this behind over a period of time after it evaporates.
  •   Plaster rendering coming away because of spalding happening inside the wall itself.
  •   Black, brown, green or yellow mould that needs a damp environment in which to take root and multiply.

Things that You Could Attempt Yourself

Sometimes the cause of basement damp is a leaking water pipe or a faulty appliance. If it’s a transient problem like that and you’re a handy person, you may just need to tighten up a joint or two. In other words, the basement is not the problem – it’s the way it’s being used.

The solution can also be as simple as redirecting rainwater where it’s discharging from a gutter, adjusting a garden sprinkler system, or unblocking the drain in a window well. Again, here the basement is quite sound. But no basement will perform well if there’s water dammed up around it.

More Serious Problems

If the above issues are not present, and there’s moisture penetrating through the basement walls from outside, then you have a real problem. Either the drainage systems that were put in place have failed, or they were inadequate in the first place. It’s pointless even trying to stem the flow of water with a cheap kit from a hardware store. You’ll most likely need a professional to assess the situation.

Avoiding All of This

We alluded earlier to the wisdom of arranging a proper survey before bidding for a home that includes a basement. Why take chances with your biggest investment? Obtain peace of mind. Have it checked out first by a certified waterproofing contractor. Know what’s on offer before you buy.



Humidity is an expression of the amount of water in the air. Humidity tends to increase during hot summer months, and is can be found indoors in any climate, especially like here on Toronto where we tend to have cold Winters and sometimes Scorching Summers with lots of rain and climate swings in between. We feel uncomfortable when the ambient humidity is high because it reduces the effectiveness of the natural cooling process we call sweating. The higher the ambient humidity level, the happier mould becomes though. And that’s a double-bind that’s best avoided at any time.

Mold in finished basement Toronto

Our basements are mini climatic systems too (although builders set out to ensure they remain as dry as deserts). That’s because the earth we build on is dynamic, and heaves and shifts naturally as its own moisture levels vary. And as it does so, it exerts massive pressure on our basement structures. The almost inescapable result is cracking, followed inevitably by water seepage.

Your Basement – A Lifelong Project

If you have a basement that’s completely watertight, then count yourself among the lucky ones. That’s because, when soil is saturated with rainwater, it’s as good as having a dam outside, thanks to force of hydrostatic pressure. Few cement-based building materials are one hundred per cent waterproof either. True foundation waterproofing uses rubber membranes on the exterior of the home. When you think about it, that’s why we build houses above the ground on foundations, and set roofs on top of them.

Finished basement with musty odour

Your Counter Measures

  1. Detect the Signs – The first thing you need to do is keep your nose tuned in to the slightest distinctive whiff of dampness, humidity or mould downstairs. When you detect something like that, it’s time to conduct a visual examination. That mould or damp spot has to be someplace, and that’s somewhere near the root cause too.


  1. Find the Spot – It’s important to remember that damp and humidity vary according to the season, and what’s happening on the far side of the basement. When it’s present on the walls it shows as a blush of water, a trickle or a dribble. On the floor, things are simpler because it forms a puddle somewhere or soaks the flooring above it.


  1. Detect the Source – If water’s dripping through the ceiling, it’s likely caused by a leaky pipe upstairs. If it appears on a wall instead, then that wall is either cracked, or the moisture is following a gap caused by an intruding pipe, or during the building process. Water on the floor is either the result of those wall or ceiling leaks, or caused by a more serious problem because you have water welling up from down below.


  1. Fix the Problem – While it is possible to seal a tiny crack from inside (although this is never a permanent solution) more serious basement damp problems require professional solutions that involve tackling the problem at its source – and that’s inevitably beyond the walls or below the floor.

We wish we could be more positive about the “instant solutions” offered on the internet and in hardware stores. At best, they conceal the problem while the hidden damage worsens. Using a dehumidifier can reduce the dampness in the basement, but it won’t fix the problem and will leave you with another daily chore of emptying the tank every day.