Why is My Basement Leaking When it Rains?

This one’s pretty simple to answer. If your basement starts leaking after it begins to rain, then rainwater is finding its way down through the ground around your foundation. Your basement is like a swimming pool, except that the foundation walls are trying to keep water out, not in. As water surrounds the foundation of your home, water finds the path of least resistance and slowly (or quickly if you have cracks in the foundation) finds a way into your basement.

To understand what occurs next, take a piece of raw concrete – this can be any shape – weigh it, put it in a container and top it up with water. Wait twelve hours before removing it and do the following:

• Weigh it a second time. It will be slightly heavier because it’s absorbed some of the water in the bucket
• Break the concrete into several pieces and observe how the water has penetrated right through the material
• Leave the concrete pieces in the sun to dry out. A few days later they should weigh the same as original piece did

Something similar happens when rainwater filters down into the soil surrounding the outside of your basement walls. It gradually saturates them until it reaches the internal surface and oozes through it. This is why it’s so important to channel water away from the foundation walls of your basement. Of course, if you have cracks and other openings, water will start leaking into your basement a whole lot faster.