Beware of the January Thaw!

Potholes, the trademark of the January thaw are not your biggest problem.

This is the time when water is going to get into the basement.

There are a few factors that combine to increase the chances.

1)     the ground is frozen,

2)     the ground around the house is not frozen,

3)     snow, ice and rain are all present around the perimeter,

4)     water travels downhill,

5)     if water is blocked, it may pool and head toward the house.

Basements are not made to be impermeable to water. So, whether it’s concrete block or poured cement, the foundation is vulnerable.

In January, the ground is usually frozen to a depth of about 2 ½ to 3 feet. The frost line is generally 4 feet, that’s the deepest the frozen ground gets in the coldest times, at least for Toronto and vicinity.

During the summer, the water runs away quickly and does not accumulate. And, even if it seeps into the ground, it starts to funnel into the earth in a cone shape, spreading out wider, the deeper it gets. So, by the time it’s wide enough to reach the basement walls, it’s often below the level of the basement floor (8 feet down).

The trick, of course, is to keep as much water away from the walls as possible:

1)     slope the ground away from the house,

2)     ensure the eavestrough and overhang keep water on the roof from dripping down the side walls close to the foundation,

3)     have weeping tiles carry away any water that gets close to the basement walls.

This doesn’t always work in the winter time. Snow and ice accumulate around the house. Then, we have a thaw, often with rain which just speeds up the process and compounds the problem.

The normal drainage away from the house may not be intact. With the thaw, the first few inches are soft and no longer frozen. Water will now head sideways through these few inches of soft ground. The frozen ground now acts as a barrier. We no longer have the “cone effect”. Water travels right over to the side of the building. Here, it finds soft warm earth heated by the foundation, perhaps 6 inches to 12 inches in width around the perimeter of the house, and down the 8 foot depth of your basement.

So, while most of the time, the correct drainage pattern will work, it’s not working during the January thaw.


There are some things that you can do:

1)     clean your eaves,

2)     ensure the downspouts are working properly,

3)     make sure they dump the water at least 4 feet away from the house,

4)     use downspout extensions,

5)     use rain barrels,

6)     place some hard surface materials, plywood, drywall, or fibreglass in problem areas

7)     make sure the grade is taking water in the right direction.

Most of the time, homeowners don’t realize that they have a water problem until it’s too late. Often, the solution is simple.

Brian Madigan LL.B., Broker

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