Foundation cracks are a common problem for homeowners, especially in regions like Montreal where climatic conditions and soil types can have a big impact. A crack in the foundation can quickly become a source of stress, since it can lead to water infiltration, structural damage and even home devaluation. Long-term home security depends on understanding how to identify the causes of cracks and recognize signs of trouble. Home owners also need to be aware of their options when it comes to repairing or preventing cracks.
Our foundation and French drain experts are here to explain the types of cracks, their causes, the signs to watch out for and what to do if you need foundation repairs.
Types of foundation cracks
Foundation cracks can take many forms. If you understand the types of cracks, you can assess whether they pose a risk and decide on the best approach to repair.
Active cracks
An active crack is one that continues to widen over time. This may indicate deeper problems, such as soil movement or foundation settlement. These cracks need to be monitored closely, as they are often a sign of structural imbalance.
Passive cracks
Unlike active cracks, passive cracks do not worsen. They are often caused by the shrinkage of concrete as it cures. Although they are generally nothing to worry about, they can still allow water infiltration and may require repair to avoid further complications.
Horizontal foundation cracks
Horizontal cracks, often found on concrete foundation walls, are caused by excessive lateral pressure. The source of this pressure may be clay soils that expand with humidity, or intense frost. Horizontal cracks are considered serious and require immediate attention, as they may be the symptom of a major structural problem.
Vertical foundation cracks
Vertical cracks are typically caused by soil settlement or water pressure. If left unrepaired, they can lead to water infiltration. However, they are generally less critical than horizontal cracks in terms of their impact on your building’s stability.
Other types of cracks
Diagonal or “stepped” cracks are often found on brick or stone foundations. They are usually caused by differential settlement, where one part of the foundation sinks deeper than the other. This type of crack may be a symptom of structural weakness and demands a thorough inspection.
It’s also important to make a distinction between shrinkage cracks, which appear as a result of concrete drying, and so-called corner cracks, often located in the corners of foundation walls and caused by external factors such as ground movement.
5 causes of foundation cracks
Cracks in foundations can result from various factors, including natural aging and construction errors. Here are the main causes to be aware of:
1. Natural aging
Over time, foundations shrink as the concrete dries out. This leads to shrinkage cracks, which often appear a few years after construction. Although common, these cracks can worsen over time if left unrepaired.
2. Freezing and thawing
Periods of freezing and thawing can impact concrete foundations. In cold regions like Montreal and other parts of Quebec, the ground expands with the frost, then shrinks. This puts stress on foundation walls that can lead to cracking. The effects are worse when foundations are not deep enough or there is inadequate drainage around the building.
3. Subsidence and other types of ground movement
Clay soils are particularly sensitive to humidity, and periods of drought can lead to shrinkage, creating voids (empty spaces) under foundations. This instability promotes the formation of cracks, particularly in concrete walls. Ground movements also exert forces on foundations and cause cracks, usually of the horizontal or stepped variety.
4. Structural and construction problems
Construction errors, such as the use of poor-quality concrete or concrete that dries too quickly, can also cause cracks. In other cases, poorly designed joints that are not adequately reinforced can create weak points in the structure, increasing the risk of passive cracks and shrinkage cracks.
Other construction problems, such as poorly designed foundations, can also cause cracks. Poorly executed excavation work around the building can weaken the foundation and lead to cracking. In older homes, the pressure exerted by an uneven distribution of the house’s weight can cause foundation cracks to form.
5. Poor drainage and water accumulation around foundations
When the drainage system around a building is inadequate or defective, water can accumulate and seep into the foundation, creating cracks and moisture problems. A faulty French drain, for example, can be a source of water infiltration and cause foundation cracks. What is a French drain? It’s a special buried pipe used to evacuate accumulated water around a building’s foundation, to prevent infiltration and moisture damage.
Blocked or poorly placed gutters can also allow water to accumulate around foundations, saturating the soil and increasing pressure on the concrete. This pressure then causes cracks, often the horizontal type, along the foundation walls.
Ground with little or no slope that is bombarded with torrential rains can also lead to water accumulation around foundations, which creates excessive pressure and can lead to cracking.
Our Montreal French drain experts can determine whether your home is suffering from a failing French drain and provide you with the right solution to fix the problem.
Signs to look out for
It’s important to know how to spot the signs of foundation cracks so you can avoid problems:
- Appearance of visible cracks in the exterior or interior concrete of the foundation wall
- Water seepage in the basement and at the bottom of walls, especially after heavy rains
- Heaving of soil around the house, especially near walls
- Doors and windows that don’t close properly or appear warped, which may indicate subsidence
- Moisture stains on interior walls, indicating water infiltration through cracks.
If your home’s foundation is showing visible cracks, it’s time to consult a crack expert for a thorough inspection.
What to do if there are cracks in your foundation
When faced with a foundation crack, you have several options. First, it’s a good idea to call in a foundation crack expert to assess the situation. The professionals at Pavé IMH can analyze the crack(s), determine whether they are active or passive, and recommend an appropriate method for repairing the damage.
Crack repair methods
Several techniques can be used to seal foundation cracks:
Injection and sealing
- Polyurethane injection: This type of repair works for minor cracks, and can also be used to seal active cracks to prevent water infiltration.
- Epoxy: This technique is generally used for larger cracks in concrete walls. Filling a crack this way will strengthen the structure of the building.
- Foundation plaster: This process improves the appearance of the foundation and provides additional protection against water infiltration.
Repair from the inside
In some cases, repairing a crack from the inside can be a good, quick solution for preventing water infiltration. Although this solution is easy, it is only effective for minor, passive cracks. The effects are often temporary, and must be supported by external work to create a lasting watertight seal.
Repair from the outside
For larger cracks or to prevent water infiltration, exterior repair is often the best solution. By sealing the cracks and installing a waterproofing membrane, you can deal with the problem at the source.
Foundation crack prevention and maintenance
To prevent cracks from appearing in your foundation, regular maintenance of the building and surrounding area is important:
- Make sure eavestroughs are installed properly and do not eject water near foundation walls.
- Verify that drainage around the building effectively prevents water accumulation, especially after periods of heavy rain.
- Beware of planting trees too close to the building, as their roots can damage the foundation.
- Inspect concrete walls regularly and take note of any new cracks.
- During construction, make sure you use quality materials (especially for concrete foundations) to minimize concrete shrinkage during drying.
Call in a foundation professional to treat your cracks
Foundation cracks can pose significant risks to the stability of your home. When neglected, they can lead to water infiltration and serious structural problems. If you see signs of active cracks or seepage, act quickly. Call on the French drain and foundation experts at Pavé IMH for a professional assessment. We can provide you with long-lasting repair and prevention solutions.