Finished basement with musty odour

Humidity is an expression of the amount of water in the air. Humidity tends to increase during hot summer months, and is can be found indoors in any climate, especially like here on Toronto where we tend to have cold Winters and sometimes Scorching Summers with lots of rain and climate swings in between. We feel uncomfortable when the ambient humidity is high because it reduces the effectiveness of the natural cooling process we call sweating. The higher the ambient humidity level, the happier mould becomes though. And that’s a double-bind that’s best avoided at any time.

Mold in finished basement Toronto

Our basements are mini climatic systems too (although builders set out to ensure they remain as dry as deserts). That’s because the earth we build on is dynamic, and heaves and shifts naturally as its own moisture levels vary. And as it does so, it exerts massive pressure on our basement structures. The almost inescapable result is cracking, followed inevitably by water seepage.

Your Basement – A Lifelong Project

If you have a basement that’s completely watertight, then count yourself among the lucky ones. That’s because, when soil is saturated with rainwater, it’s as good as having a dam outside, thanks to force of hydrostatic pressure. Few cement-based building materials are one hundred per cent waterproof either. True foundation waterproofing uses rubber membranes on the exterior of the home. When you think about it, that’s why we build houses above the ground on foundations, and set roofs on top of them.

Finished basement with musty odour

Your Counter Measures

  1. Detect the Signs – The first thing you need to do is keep your nose tuned in to the slightest distinctive whiff of dampness, humidity or mould downstairs. When you detect something like that, it’s time to conduct a visual examination. That mould or damp spot has to be someplace, and that’s somewhere near the root cause too.


  1. Find the Spot – It’s important to remember that damp and humidity vary according to the season, and what’s happening on the far side of the basement. When it’s present on the walls it shows as a blush of water, a trickle or a dribble. On the floor, things are simpler because it forms a puddle somewhere or soaks the flooring above it.


  1. Detect the Source – If water’s dripping through the ceiling, it’s likely caused by a leaky pipe upstairs. If it appears on a wall instead, then that wall is either cracked, or the moisture is following a gap caused by an intruding pipe, or during the building process. Water on the floor is either the result of those wall or ceiling leaks, or caused by a more serious problem because you have water welling up from down below.


  1. Fix the Problem – While it is possible to seal a tiny crack from inside (although this is never a permanent solution) more serious basement damp problems require professional solutions that involve tackling the problem at its source – and that’s inevitably beyond the walls or below the floor.

We wish we could be more positive about the “instant solutions” offered on the internet and in hardware stores. At best, they conceal the problem while the hidden damage worsens. Using a dehumidifier can reduce the dampness in the basement, but it won’t fix the problem and will leave you with another daily chore of emptying the tank every day.



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Waterproofing & Foundation Specialists at Nusite Contractors Ltd
As a family-owned waterproofing and foundation repair business with over 30 years of experience in Toronto, we are proud of our work and stand by it with a full warranty. We’re a service company, working for you. We make sure our customers understand the entire building and repair process, and ensure that our work is done properly and made to last.

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