What’s causing moisture in basements and how to fix it

Excess moisture in basements is a fairly common problem. Indoor humidity, ground waters and leaky basements are often the causes of moisture in basements. Moisture can damage the furnishings and finishing of your home. It may also cause the foundation to deteriorate, potentially compromising the structural integrity of your home. You cannot ignore the signs of a leaky basement, as the problem will not fix itself (as much as you might like to hope it might) and will ultimately lead to further, more expensive issues down the road. Unfortunately, it can also be an extremely detrimental one.

Signs of Moisture in Basements

You might be wondering – how can I tell if I have a basement moisture problem?

Here are the most common causes for moisture in basements:

  • Odor/presence of mold or mildew
  • Stains on walls or floors
  • White powder on concrete/brick walls (called efflorescence)
  • Drywall damage (sagging, blistering)
  • Rusting of pipes/plumbing
  • Rotting joists, studs etc.
  • Trickling or standing water

If you notice any of these things, it is imperative that you take action right away. You need to find the cause of the problem, that way you can determine what steps to take next in order to resolve it.


Water in your basement can come from several different sources. If you have a bathroom in your basement, for example, there could be excess humidity causing condensation. Dryers can also contribute moisture to the interior environment. These sources of moisture are relatively easy to combat. Sometimes plumbing can spring a leak – a much more serious issue, though usually straight-forward to fix. It is important to check your systems regularly, as detecting a leak earlier rather than later is preferable.

Another serious source of moisture is from rain or groundwater. Water from outside the home leaches in through the basement. This is generally a result of improper drainage, causing water to remain in contact with your foundation. The longer that your foundation is exposed to water, the more likely it is to become damaged. If you have discovered you have a leaky basement, do not panic. Check out the potential solutions below.


1. Improve the basic interior environment of your home.

As mentioned before, there can be things inside your home that are contributing to moisture in the air. It is a good idea to install a fan in any bathrooms to increase airflow and help things dry out. A dehumidifier can also be a worthwhile investment, especially if you live in a particularly humid climate.

If you have any water leaks inside your home, they need to be dealt with immediately. As mentioned before, plumbing issues can be serious but for the most part they are quick and easy to fix. You may need to contact a plumbing professional to resolve the issue. The good news is that if a plumbing leak is the only source of moisture in your basement, once it is fixed and everything is dried out you should not have any more problems.

2. Reduce moisture around outside of your home.

One of the easiest things you can do to protect your basement foundation from water damage is to make sure your gutters are cleaned out and direct all downspouts away from your house. Clogged gutters cause water to overflow and run down the sides of your house. This can potentially expose your foundation to moisture (especially if you do not have your basement properly waterproofed), making it more susceptible to deterioration.

It is also important to verify what way the soil is graded around your home and improve it if necessary. If the ground is sloped towards your home, you are going to have more water pooling around the foundation, again increasing the risk of damage. You also want to consider keeping flower beds away from the edge of your house. Similarly, it is ideal to keep large bodies of water (like feature ponds) as far away from your house as possible. This will limit adding extra water to soil around home.

Exterior basement waterproofing is another valuable investment. Simply put, soil is removed from around the basement wall and a moisture barrier is installed. A waterproofing professional will be able to determine what time of barrier is needed for your specific foundation, as well as any other prep work that may be necessary. Once the barrier is in place, a drainage system is then installed.

3. Invest in interior basement waterproofing.

Interior basement waterproofing is a great option when exterior waterproofing is not an option. Sometimes the physical location of a house or the soil conditions surrounding it make it impossible to employ exterior waterproofing. In these cases, interior waterproofing is recommended in order to prevent the impacts of a leaky basement. It is also imperative that any cracks in the foundation are dealt with as soon as possible. You will need to determine what type of crack you are dealing with in order to make the appropriate plan of action for repair (check out foundation cracks and how to fix for more info).

Hire a professional

Do not ignore the signs of a leaky basement. Contact our basement waterproofing specialists in Toronto today for a free inspection of your home’s basement.

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