Moisture and Leakage Warning Signs in Ontario Basements

A recent survey undertaken by Health and Welfare Canada found that 38% of Canadian homes had indications of excessive dampness or mold. And even newly constructed basements, which may remain dry for years, can suddenly become susceptible to moisture infiltration as settling occurs or conditions change around the home. Many home sales get re-negotiated or canceled when the building inspector discovers moisture. What will the building inspector look for?

Damp spots on basement walls in Hamilton, Ontario

Damp Spots on Walls

An unpainted block will turn a darker grey when it's wet. A painted wall will show discoloration, or a darkening of the paint. A poured wall might show discoloration. In any case, there might be white or dark outlines surrounding the area, which means that either its leaked before, or substantial moisture has come through in that area. Outlines on the foundation are evidence of previous water leakage in the basement.

Mold, mildew in Kitchener, ON basement

Mold or Mildew

Mold and mildew are living, breathing organisms that grow and multiply anywhere there is excessive moisture. Both mold and mildew can grow in the walls, carpeting, furniture, or anywhere else it can find an organic food source such as wood, insulation, paint, paper.

Microscopic spores are the reproductive mechanism by which mold spreads and these spores can remain dormant. That means that even if you don't smell or see  mold or mildew in your basement or crawl space, it may still be there.

Peeling paint on basement walls in Guelph, Ontario

Peeling Paint

When paint gets old, it can peel off the surface it was painted on, like the peeling paint you may see on old homes. But it doesn't peel off just because it's old. Paint may peel off because:

  1. It was the wrong kind of paint for the material it's on.
  2. The surface wasn't properly prepared.
  3. There is dampness or moisture in the wall you are trying to paint.

Paint will not stick to damp surfaces. It will discolor, and water vapor will peel the paint right off the wall or poke holes in it. Look for blisters where the paint has bubbled away from the wall. This is a sign of moisture in the basement or crawl space.

Rust in Woodstock, Ontario

Rust on Appliances or Jack Posts

Metal is susceptible to rusting when there is excessive moisture in the environment. The rust may begin on fuse boxes, water heaters, jack posts or appliances due to excessive dampness and humidity.

Once rust occurs, you have to completely remove the rust and repaint as soon as possible, and then look for the cause of the moisture. If not, the rust will reappear again and again.

Musty, mildewy odor in basement or crawl space

Musty Odor

Musty "old basement" odors are merely the result of the decay process associated with mold, mildew and dry rot. It is the odor given off by the decaying material.

Once you smell a musty, mildewy odor, look for the source, and try cleaning any item that has the smell. If it returns, you'll need to replace any items that smell of mildew.

Dry rot in basement or crawl space

Dry Rot

Basement dry rot is a brownish-black fungus growth on walls, clothing and other surfaces; it typically grows on wood surfaces.

Keep in mind that dry rot is a byproduct of the decaying process - you'll need to not only replace whatever is damaged, but also find and cure the cause of the dry rot forming in the first place.

Cracked foundation in crawl space or basement

Foundation Cracks in Walls and Floors

Foundation or basement cracks can come in a variety of shapes, sizes and directions. For example, you may see step-cracks on the wall. You might find vertical cracks, or horizontal cracks in your basement. In any of these cases, something is causing this to happen - cracks don't usually appear naturally. It could be from settling, pressure on the walls or under the floor, or any number of other causes.

We have a solution for bowed foundation walls!
Efflorescence on basement or crawl space walls in Ontario

White Chalky Substance on Basement or Crawl Space Walls

Concrete is made up of limestone, clay and mortar, and aggregate (stone). That white outline or spot you see is the calcium in the block leaching out. It's an indication of water, excessive moisture, and is something you should pay attention to. It's called efflorescence.




Always get sound professional advice - ask the company giving advice what they specialize in before you tell them you have a basement problem. If they don't say 'Basements' in their first response consider finding another company.


Do not rely on the advice of any individual or company that is not a true dedicated basement waterproofing specialist.

Wherever possible include drainage to alleviate basement or crawl space water pressure as part of your solution.


Never rely solely on 'bonded' waterproofing such as render or asphalt to hold back water pressure. Over time it will fail.

Choose the systems you need based on its technical merits and your performance criteria.


Do not choose the wrong system just because it is cheaper - it will almost always cost you more for a superior basement waterproofing system. Many people have paid for the wrong system and installed the right one some months or years later.

Always choose a system that comes with good quality sales service.


Never choose a system that does not include sales service.

Always assume that water pressure could increase in the future - this might be due to high rain fall or a burst water-main.


Do not rely on the past history of a basement to predict its future likelihood of flooding.

If you have any of the problems listed and would like more information, please contact Omni Basement Systems for basement waterproofing in Oakville or the surrounding areas. We service Hamilton, Burlington, Kitchener, St Catharines, Guelph, Cambridge, Brantford, Niagara Falls, Milton, Waterloo, Welland, Stoney Creek, Georgetown, Dundas, Grimsby, Ancaster, and the surrounding areas in Ontario for basement waterproofing.

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