Vertical Foundation Wall Cracks

A foundation is the structure on which a home or other building rests. It may be a simple trench filled with concrete on which the brick walls stand. It could also be a concrete-reinforced sheet under the entire building. Where the ground slopes, there may be foundation walls as well, to make up the height difference.

Where a basement is constructed beneath a dwelling, these foundation walls go up to full room height, and receive immense pressure from the weight above them. Unfortunately not all builders make good engineers. If the forces bearing down on foundation walls are incorrectly calculated – or they are inadequately supported by their footings – then the walls will inevitably crack.  Cracks in the foundation can also be a result of shifting of the earth around the foundation, causing enough movement and stress for it to crack.

Toronto home with vertical crack in foundation

Warning Signs

Vertical foundation cracks usually develop during the first few years after construction finishes, as the building settles and the concrete finally cures. They typically start as hairline cracks that progressively open up. A structural engineer is able to measure their movement, and to determine whether the cracks are new developments, or older history.

It is also possible for basement wall cracks to develop when peripheral events affect an existing structure. These could include alterations to the property, blasting in the neighborhood, or even an earth tremor. It’s important to monitor for basement cracking during events like these, so that an insurance or other claim may be lodged before the opportunity expires.

Consequential Problems

Most times a mildly cracked foundation wall is more of an irritation, because it admits moisture and even drops of water through it. Nonetheless, homeowners are strongly advised to consult an a qualified contractor or engineer if in any doubt. The more serious consequence is often a reduction in the value of their home, since buyers often run a mile from the sight of cracks.

“Solutions” That Don’t Always Work

The only sure-fire way to seal a leak is at its source (unless it’s a hairline crack that may be filled with polyurethane). As a professional foundation contractor in Toronto, we get hundreds of calls a year for foundation cracks, including following up on poor attempts to fix them.  The following are examples of botched jobs we often come across:

  • Amateurish attempts like papering over basement wall cracks or filling them with commercial caulking seal. These are inevitably bound to fail as efflorescence builds up behind the sealant causing it to peel away. It’s also almost impossible to obtain a dirt-free, perfectly dry surface with which to bond.


  • Commercial filling with hydraulic cement or other rigid substances is also bound to fail, because the structure will still shift with seasons, while the hydrostatic pressure from outside continues unabated. The same applies to epoxy seals to a lesser extent. They may sometimes work for years though – provided they are attached to a perfectly clean dry surface

Flexible, expandable urethane sealants may work where a crack has stabilised. However their elasticity is limited, while cracks can expand by up to 100% quite quickly. For this reason they are not ideal.

The Real Solution

Where vertical foundation wall cracks are serious, or there’s water pouring through them in the rainy season, the only viable solution is to remove the outside soil, to install a french drain or other soak-away system, and to apply a flexible waterproofing sealant or membrane from the outside.

Repairing and/or waterproofing a foundation  can be expensive for the homeowner, it’s also alot of work. If you’re going to do it, be sure it’s being done by a professional that will offer a guarantee on their work and has experience working with foundations.



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.




Many of the homes in Toronto are old, some approaching 100 years old or older.  As the years pass, the foundations of these older homes could become damaged. Even homes that are not quite as old could have severe structural damage due to water pressure, ground shifting, or even faulty construction.These structural damages can affect the structural integrity of your home if the situation is not addressed and properly corrected.  Additionally, a damaged basement foundation will result in potential damage from water leakage, and potential health problems with the onset of mould infestation.

Here 5 common causes for a damaged basement foundation.


Concrete Foundation Wall becomes Bowed

Before any cracks appear in your basement wall foundation, one of the key structural signs that your basement foundation is damaged is when the wall or walls becomes bowed. A foundation wall which has become bowed is a clear indication that the structural integrity is undergoing a serious problem.

A bow in the wall is a sign that an inordinate amount of uneven pressure is being applied to the wall.  Eventually, a bowed wall will worsen over time if the problem is not addressed and will begin to crack. Cracks will begin to appear in the exterior of the wall before there is any indication of cracks on the interior of the wall.

a bowed cinderblock basement wall

Brick Foundation Wall becomes Bowed

Brick foundation walls are generally uncommon and found mostly in older homes in the Toronto area.  However, like any other foundation wall, brick walls are also subject to forces of pressure and can become bowed over time.

A bow in a brick wall is not nearly as noticeable to a visible inspection, nor as easily spotted as a structural pressure bow found in a concrete wall. The only visible clue you might notice is the displacement and scattering of loose mortar on the floor as cracks appear.

The important thing to remember is that once you have discerned a bow in your brick foundation wall is to understand that the structural integrity is also being threatened. If you begin to notice any cracks on the interior, you can be assured that the exterior is also cracked.

toronto home with a bowed wall

Concrete Block Wall Step Cracks

This problem is generally found in foundation walls which have been made from concrete blocks. These types of cracks often appear where you have a basement window casing. Frequently the cracks will begin horizontally, and at the bottom corner of the window casing.

Gradually, over time the cracks begin to step down like a set of stairs or steps, and follow the joints of the concrete blocks progressively below the original crack.

Causes for step cracks can come from different causes including pressure from tree roots, or a shift in the soil pressure against the wall for example. Another reason is that the foundation wall simply cannot withstand the load from the upper portion of the home and cracks from structural fatigue.

The stress in step cracks is different from cracks which are either horizontal or vertical. In horizontal or vertical cracks, the stress is pulling the structure in opposite directions. In step cracks, the structural stress and damage is more dangerous because the pressure force is occurring in all four directions at the same time. It means that the structural integrity of the wall is seriously diminished, and the wall has become extremely weak. The wall must be stabilized as soon as possible.

a stairstep crack in a cinderblock basement wall

Bows in a Poured Concrete Wall

Bows in a poured concrete wall are also sign of destabilization of the structural foundation. Bows in these types of foundation walls will also result in cracks which start on the exterior and are later visible on the interior. Cracks in a poured concrete wall can occur anywhere, and can be either roughly vertical or horizontal in nature. They can appear almost anywhere in the wall from the footings to the top of the wall. One crack will usually result in other cracks appearing later on if the problem is not fixed.

a poured concrete home in toronto with a cracked basement wall

New Home Foundation Wall Cracks

You might be surprised that getting cracks in a new is more common than you might think. The main cause for cracks in new homes is generally caused when builders, who are often on a rushed schedule, fill in the excavated foundation exterior of a basement structure before the concrete has adequate time to dry and set properly.

The types of cracks can vary quite dramatically because of this reason, and can vary from small hair line to fractures to much larger and visibly apparent cracks. You could be tempted to ignore these warning signs because you might think that because the wall is new that it is still strong.

This however, is not the case. No matter the age of the foundation, cracks are a clear sign that the structure has become damaged. The situation will worsen over time if steps aren’t taken to fix the problem.

foundation crack in a basement wall