basement waterproofing

Basement Leaks Through a Concrete Block Wall


Concrete Block Wall Basement in Toronto

Many homes in Toronto and the surrounding GTA have poured-concrete foundations, but some of them are made of concrete block, which is often referred to as concrete masonry units (CMUs) or cinder blocks. The walls of concrete block foundations sit on a footing which is a concrete-poured pad that is wider than the building’s foundation wall. This helps to distribute the home’s weight load. The foundation’s construction starts with pouring the footing inside a trench which contains metal or wood forms. The footing needs to sit lower than the freeze line and possibly deeper if there’s going to be a full-height basement.


Foundation Footings

The footing’s thickness and width depends on the construction and size of the home as well as the soil’s load-bearing capacity. During the basement excavation, the first row of concrete block is laid on the footing when it has cured to describe the structure’s perimeter. For foundation walls, the typical thickness of the concrete block is eight inches. However, foot-thick blocks are sometimes used for heavier loads and higher walls. More courses of block and mortar are added in a brick-like pattern until the proper height is reached. At this time, any openings and windows are built and the mortar in the wall is given time to  cure.

If there are hollow cores in the block walls they may be filled completely with mortar, but usually the edges of openings and corners of the wall are filled. In addition, extra strength may be added with steel rebar. Once the walls are finished the basement floor is poured with concrete and the ground floor framing is completed. The foundation is now supported at the bottom and top and it’s backfilled and compacted with soil while construction begins above the ground.


Fixing a Leak in a Concrete Block Foundation

Poured-concrete and concrete block foundations both have identical load-bearing strength, but concrete block walls are more susceptible to any type of lateral pressure which can result in seepage problems. This is because water can seep into a basement through concrete block walls via the porous blocks and any cracked mortar joints. It’s recommended that you waterproof a home’s block foundation by installing a waterproofing membrane to the exterior. This method can be done while the building is being constructed or by excavating around it.

The exterior membrane consists of asphalt-modified polyurethane. It’s applied in a thick coating to the exterior of the foundation walls and it created a barrier which helps keep out water. The waterproofing membrane is different than a damp-proofing spray as the spray is a thinner liquid which is sprayed over foundation walls when the home is built to keep condensation out of its interior. The membrane can be improved with exterior drain tile when the water table is high. The drain tile is designed to carry ground water away. In addition, drainage board can be installed on the walls as a method to help protect the exterior membrane by channeling the water downward.

If you don’t have the option of exterior waterproofing, then interior drain tile can help keep a block wall from allowing water through it. This often sees the installation of a vapor barrier on the inside walls which transports any water to the drain tile. This can be kept from view as a finish wall can cover the vapor barrier.

No matter what the reason is for your damp basement, if you have a concrete block foundation that needs to be waterproofed please feel free to contact our team of professional contractors at Nusite. We have over 30 years of experience dealing with concrete block walls in the GTA and will gladly schedule a visit to your home for a free inspection and estimate.

When You Need To Install a French Drain System

When You Need To Install a French Drain System

A French drain system can be the ideal solution for Toronto area homeowners who are dealing with a wet basement and/or soggy yard. Water naturally flows downhill and always takes the easiest route it possibly can. This concept is basically what’s behind a French drain system as it’s a trench which is sloped slightly and filled with a pipe and round gravel which diverts the water away from the building. The concept was invented by a 19th-century American named Henry French and is still an effective system today.

The French drains gives water an easy avenue to flow through. It runs into the gravel-filled trench and then flows into a perforated pipe which is sits at the bottom of the trench. The water can travel quite freely through this pipe and its emptied from the home at a safe distance. In general, the bottom of the trench should slope approximately one inch for each eight feet in the direction you’d like the water to flow. The water can then be emptied to a drainage ditch, a low-lying section of the property, the street or a dry well etc.

Soggy Property
Those who are dealing with surface water and soggy areas of their property can benefit from a French drain system as can those who suffer from wet basements. When it comes to soggy areas, the French drain, which is also known as a curtain drain, runs horizontally across the property and uphill from the area which you’d like to dry out. The drain doesn’t necessarily need to be deep as most of them are about two feet in depth and approximately 1.5 feet across. If the drain has to pass through treed areas or shrubbery a solid pipe can be used to make sure roots don’t grow into it and clog it.

Wet Basement
With a wet basement, a deep French drain is a good option. This system is also known as a footing drain. It is located at footing level and runs around the home’s perimeter. This enables it to catch the water before it’s able to flow into the basement. These systems are easy to install during the construction of a building, but can also be added later if necessary. If the basement is tall then the foundation footing may be quite a few feet down. In some instances, landscaping, walkways and decks may have to be taken out to install the drain. If there isn’t enough slope for the system to be effective the water may need to be sent via a sump pump to the storm drain system.

French Drain System

Interior French Drain
The interior French drain is designed to intercept the water as flows into the basement and is considered the best option when it comes to a dry basement. If the basement is finished though it means the interior walls will need to be moved before the system can be installed. A channel is cut around the basement floor’s perimeter and the concrete is chipped out. Perforated pipe is then installed all the way around. This sends the water to a collection tank which is sunk into the floor and it’s sent to a storm drain or the yard by a sump pump. The channel contains a thin concrete layer except at the edge and this catches water which may dribble down the wall.

If you’re interested in learning more about French drain systems please contact our team of professionals at Nusite. We’ll be glad to answer all of your questions and schedule a house call to discuss your unique situation. A French drain may be just the thing you’re looking for if you basement is continually wet or your property consists of soggy areas which won’t dry out.

What Basement Waterproofing System is Best?

What Basement Waterproofing Is Best

There is one concern that all homeowners with basements have… a wet basement. Chances are if you are reading this article you either, have a wet basement and are looking for a solution or you are worried about having one in the future. No one wants to deal with leaking or flooding in their basement, so it is important to take steps to waterproof your basement before the need arises.


If you do a quick search online for waterproofing your basement there are three main solutions that you will find: crack injection, interior weeping tile and exterior waterproofing.


  1. Crack Injection – Using a product for crack injection is a common way to repair cracks in your home’s foundation and one of the least expensive. With all of the freezing and thawing that happens throughout the year it is common to end up with small cracks in your basement walls over time. Crack injection is one solution for repairing any of the small cracks that are allowing water to leak through. However, while this solution can keep water from entering your basement it is a temporary solution.


Crack injection does not address where the water is coming from so you will continue to have water trying to enter your basement and it will eventually find a new route. A long term solution will still be necessary. While this can help keep water out for a short time, it is not truly a long term waterproofing solution.


  1. Interior Weeping Tile (French drains) – A solution that is a step up from crack injection, is installing interior weeping tile. Just like crack injection, installing interior weeping tile is not a true waterproofing solution, but more of a way to manage the water that has entered your basement. This system is also known as an interior French drain, which is not named after the country, but the creator Henry Flagg French.


When installing an interior French drain in your basement you have to break up the concrete flooring around the perimeter of the basement. Once that has been completed crushed stone is put down and a drain is install that will pull the water to a sump pump. The sump pump then works to drain water away from the house. It is important that each step is completing correctly using the right materials or else you could end up with a clogged drain and a wet basement.


When installed correctly interior weeping tile can help to manager any water that enters your basement. This method is more effective than crack injection, but is still a water management method instead of actual waterproofing. This is a popular solution for wet basements because it is more affordable than exterior waterproofing.

Exterior Waterproofing


  1. Exterior Waterproofing – With all of the options out there, exterior waterproofing is the only way to truly waterproof your basement. The process is the most extensive of the methods that we have mentioned but also the most effective when installed properly. Exterior waterproofing stops water from entering your basement and helps to eliminate wet walls.


To install an exterior French drain you need to dig a trench around the entire perimeter of your home. This can mean removing shrubs, plants and patios if needed. A French drain system is installed to drain water downward and away from the foundation. While the dirt is removed from the foundation a waterproofing membrane is added to the exterior of the foundation. The combination of the waterproof membrane and the exterior weeping tile system keep water from working its way into your basement.


While the other methods work to properly manage the water when it reaches your foundation, exterior waterproofing also works to keep the water from getting to your foundation in the first place.


Choosing the best waterproofing method for your basement

When considering which method of waterproofing is the best for your basement it is important to weigh all of the factors. Make sure to consider not only the expense of the repairs and installation but also the way that the water is entering your home. It can be well worth investing a little more into your basement’s waterproofing now to avoid a problem in the future.


If you are interested in speaking with a professional on the best options for waterproofing your basement call Nusite Waterproofing today. With free estimates, written guarantees, flexible financing options and a 30 year A+ rating from the BBB, we have you covered for all your basement waterproofing needs.

The Most Common Type of Basement Leak

leaking basement Toronto where basement floor meets wall

Water leaking through top of foundation wall

As a waterproofing contractor here in Toronto, I’m often asked what is the most common cause of a leaking basement. But first, I want you to conduct a small experiment for me.

Take a used tin can (baked beans, peas, whatever) and remove the bottom end. Then, place the open-ended can in a cooking pot that’s a little taller than it. Hold it down as you slowly fill the pot with water to just below the top end of the can. While you watch:

  • Water seeps into the can past the bottom end
  • The rate increases as the outside water-level rises
  • Finally, the water levels are the same on the inside and the outside

Two things are relevant here. First, there was no seal between the bottom of the tin can and the cooking pot. Secondly, the water found a way inside the can because of what’s called hydrostatic pressure.

Basement Basics

A basement is comprised of two separate structures which are by definition underground. These are:

  • A concrete floor set in an excavated space (the “cooking pot”)
  • A rectangle of four walls standing on it  (the “tin can”)

If you were to fill the excavated space with water, this would place hydrostatic pressure on the structure. In turn, this would seek relief by entering the basement through the concrete floor and walls. These may be well waterproofed; however, as the structure settles, the joint between them weakens and gives way to water pressure.

And that, my friend, is the most common cause of leaking basements. In fact, it’s almost built into the basic design. Just like your camping tent in a storm, the leak is usually at the seam.


Interior weeping tile system image

Interior Weeping Tile System

How to Avoid the Problem

Do you remember how the flow of water into the tin can increase as the water level rose? The same is equally true of a leaky basement. The correct solution is installing an outside drain at floor level. This leads the underground water away as it arrives, so it never builds up enough pressure to become a problem.

In the basement water-proofing industry we call this a weeping tile or french drain system. They’re simple to install during initial construction, but a messy job to repair and install after construction. Getting a certified and insured waterproofing contractor is important if you think you may need this type of work.

Basement First-Aid

In my decades in the basement repair business, I’ve come across countless botched repair jobs involving water-proofing interior basement walls. While waterproofing your foundation can be effective if done properly, if there is an outside water source placing constant pressure on your foundation, it probably won’t last. The hydrostatic pressure invariably dislodges the material, especially since the area was inevitably damp when the seal was applied.

The only solution that’s effective is an interior water-catchment system that feeds a sump pump to an outside drainage point. It’s expensive though. However, it’s also better than abandoning a working basement, which could otherwise add good value to your home.

How Can I Tell if a Foundation Crack is Serious?


As a homeowner, seeing a crack in your foundation can certainly be cause for concern. Here in Toronto, the harsh Winters and rainy Springs and Summers can cause havoc on our home’s foundation.  Even if it hasn’t happened to you, many of us have heard horror stories of water damage and shifting foundations that can cost a pretty penny to repair. So, how can you tell if the small crack you discovered signifies a much larger problem? Read on to find out.

What Different Types of Cracks Can Signify

There are several different types of cracks that commonly occur within the foundation of a home, each of which can signify a different problem:

  • Horizontal Cracks – A crack in your wall that extends horizontally, or looks like a stairstep, commonly signifies a problem for homeowners. These cracks leave your foundation susceptible to lateral pressure and with the natural expansion of the ground around your foundation, with moisture, it can actually cause your wall to bow around the crack. A horizontal crack can eventually lead to the entire failure and snapping of the foundation walls if not cared for appropriately. This type of crack cannot be fixed by simply filling it, it will require professional attention to truly repair.

Horizontal crack in Toronto foundation home

  • Vertical Cracks – As concrete and the foundation of your home settle it can cause vertical cracks to occur throughout your foundation. These cracks are quite common and can be easily repaired by filling the crack with filler materials to prevent further spreading.

Toronto home with vertical crack in foundation

  • Diagonal Cracks – A diagonal crack is typically an indication of a fracture that has spread over time, so a simple filling might not fix it permanently. It is a good idea to get these types of cracks stabilized and reinforced by professionals so that further spreading does not occur.ConcreteDiag220DFs (1)

Depending on the types of cracks that you are noticing within your foundation, you can better determine the next step that you need to take to protect your investment.

Even Minor Cracks Need to Be Monitored

Even if you have a vertical crack, you want to be sure that you monitor all cracks regularly. Expansion, bowing of walls and leaks can only cause more damage to your home and cost you more money. A great way to monitor your cracks is to use a pencil to mark the ends of a crack with the date reviewed. A few months later you can return to the crack and see if it has changed or expanded. If you notice an expansion then perhaps it is a good idea to seek professional assistance to ensure that you home is not in danger.

When to Get a Professional Involved

If you notice that a crack in your foundation has seemed to worsen, or you have a horizontal or diagonal crack, then you are going to want to consider bringing in a  professional. A contracting company that specializes in foundation repairs can give you an assessment of whether it’s a minor problem or a more serious matter.  If it’s a very serious problem, a structural engineer will likely be recommended to assess the foundation.

Your home is your sanctuary and an investment that should be protected, don’t let a little foundation crack threaten your home and family.


Have questions about cracks in your foundation?  If you live in Toronto or the surrounding GTA, we Nusite Group offers a free in-home inspection and assessment of your foundation cracks.  You can contact us here for more information.