• Nusite Contractors Ltd.

Should I worry About Cracks in my Foundation Floor?

Updated: Aug 6

This blog discusses cracks in foundation floors. Topics include; Should I be worried about a foundation crack, why cracks develop, strategies to fix foundation cracks, and issues caused by foundation cracks.

Do you have cracks in your foundation floor?

Cracks are a common feature in most homes, especially here in Toronto where we have older homes with foundations that are decades old. There are many things that can cause cracks, including poor initial workmanship and/or a shifting foundation.

Should I be worried about a foundation crack?

Don’t freak out some cracks are harmless and the one you see may be very common. It’s actually a good thing that you found this crack because now all you need to do is determine what’s causing it, and the earlier you find it, the higher the chance it can be repaired. We recommend calling a Foundation Repair/ Concrete Specialist. They are the individuals who have the tools to determine the cause of the crack and will recommend a repair strategy.

Remember, if you found this crack without any other issues, consider yourself lucky. You may still have time for a quick, easy, and cheap fix because once cracks form in the foundation, water is usually soon to follow.

There are two reasons why cracks may develop.

  1. The earth beneath the foundation was inadequately compacted before the concrete pour. This means there is a little extra weight, causing uneven support for the foundation.

  2. The concrete cracked as it dried out (This is common with concrete). Some builders keep concrete flooring moist for longer periods of time to avoid this.


Fixing Foundation Floor Cracks


Like most things in life, there’s a right way and a wrong way to seal floor foundation cracks.

The wrong way is to conceal the problem with surface filler. The recommended strategy is to pour in a polymer compound that forms a bond with both concrete sections.

The best solution for wider cracks is to use an epoxy filler to recreate the original monolithic pour. This strategy is the most expensive one and you may need a concrete flooring specialist with right injection tools.

Damp and Mold

There is always moisture underground because that’s where rainwater naturally ends up. The force of gravity pressing down on the earth makes groundwater surprisingly intrusive. If you ignore non-structural floor cracks, don’t be surprised to find water bubbling up through them after heavy rain. If your home sits on a high-water table cracks can be an open invitation for a wet basement.

This can cause serious issues in underground basements because many homeowners forget to inspect them. Damp areas below the earth’s surface are perfect conditions for moss and mold to grow, especially if the room’s kept tightly closed with no flow of fresh air.

Gas Intrusion

Undetectable methane and radon gas can accumulate in pockets underground, which, is seldomly tested for during surveys. A builder may disturb one and cause the gases to escape. While the foundation work is supposed to keep them harmless, a cracked basement floor may not. Methane gas is violently explosive. Radon gas is the most potent cause of lung cancer after cigarettes. This is nothing to stress over, however important to keep in mind when a crack is found.

Insect Infestation

Concrete floor cracks can be a breeding place for ants and termites, from where they can fan out in the home. Tackling the issue upstairs is not an effective place to start, as they are most likely reproducing in the floor below.

About Nusite


Nusite Contractors Ltd. has been proudly serving GTA homeowners for over 30 years! We are a family business and take pride in customer service and professional work. You can contact us here to schedule a free consultation and written estimate! We would be happy to help!


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