Basement Leaks 

Why is My Basement Leaking?

”If you are planning to finish your basement and your foundation has any visible cracks, even if they are not leaking at present, don't take a chance by finishing your basement! It is a wise decision to have them repaired now!"

There are different ways in which water can enter your basement from outside your home:

  • cracks on foundation walls
  • rod holes (also known as tie holes) 
  • Service holes (such as hydro lines, plumbing, etc) 
  • Honey comb concrete 
  • Basement windows below grading 
  • Side door 
  • “I” beam pocket

Cracks in poured concrete foundation walls are a fact of life. These cracks are due to drying shrinkage and thermal movement and are the most frequent causes of cracking.

Drying shrinkage is caused by loss of moisture from cement paste constituent, which can shrink by as much as one percent. Also common are those caused by structural settlement, overload or earthquakes. Most cracks initiate in the first 30 days after pouring the concrete structure. Even the smallest undetected crack can, in time become larger and start a structural or leaking problem. Some may never grow any further and will not cause any leaking or structural problem. 

It is much cheaper (about 1/3 of the cost ) to have cracks repaired from inside your home before the leak starts than if you finish your basement and then find a leak and then have to have the crack repaired from outside your home. You can save your self thousands of dollars in the cost of replacing drywall, furniture, carpet, trim, etc. and the cost of removing mold from your home. Mold is a very dangerous health issue, most of the time water and moisture that is trapped inside the walls causes mold to grow. According to Health Canada studies, mold is a fungi that grows in damp environments. Mold spores contain allergens and irritants that often cause people living in the house to suffer from allergic reactions and respiratory diseases. Humid or damp conditions in your home can encourage the growth of mold and dust mites. Mold can develop from poor ventilation, flooding and building leaks. Moldy smells from basements, carpets and gypsum board (drywall) are a sign that they harbour fungi. Canada Mortgage and Housing Corporation

The majority of insurance companies won’t cover this type of damage. If your basement is rented, this will create an inconvenience and health issue for your tenants.

In the event you are selling your house, and the buyer hires a professional Home Inspector, which most of buyers do now days, this problem can be easily be detected by an inspector with a moist measurement instrument and you will most likely end up having to fix the crack before the new buyers take possession and you will be responsible for the cost to do so.


Rod holes are holes left when the pins, held in the forms to pour the concrete are removed. Some basements have the upper 4 feet insulted, some all the way in part of the basement, basically any exposed wall to outside (4 feet bellow grading). Some times no crack is visible but you see water coming in, most likely a rod hole is leaking.

In the summer, when humidity levels are high, condensation might occur behind the poly (especially if you don’t have a air conditioning). The insulation gets “dark”, is getting wet.By pressing the poly against the concrete, you might see small amount of water dripping on bottom of plastic, then is not a leak, it is just condensation. The same happens in your cold water pipes running in the basement, if humidity level is high, it will condensate on your pipes and drip. For this two situations a dehumidifier is recommended.


Most of cases your hydro line comes into the house above grading, but in any event if your service lines are lower or same level than grading, it is another place where is common to see water coming in. If water comes in near your electrical panel, you must solve this problem imediately.


During pouring of the concrete into the foundation forms, if the concrete paste wasn’t shake enough some times are areas with more stones than concrete and it will create what is known as “honey comb concrete”. If this area is bellow grading some times allows water in, again, it can be easily solve by injecting polyurethane in the area , which will fill any cavities and penetrate to the other side of the wall.


If the distance between your soil and the bottom of the frame of the window is less than 6 inches , a window well with a vertical wiping tile with cloth cover connected to the weeping tile that runs around the house. Then 2 feet of ¾ crash stone should be inside the well.


Same rules applied , if the bottom of the door is bellow grading or same level, water might come in . This door is installed after the foundation is poured or simply the concrete is cut to accommodate one, mining a joint between the concrete and the bottom of frame is created and water comes in. Polyurethane can be injected in than joint and your problem is solved.


It is where the “I” beam seats in your foundation, sometimes a concrete support as part of the foundation is built, some times the upper foundation wall is chipped with with a hummer chisel to accommodate the “I” beam.Now the area where the foundation was chipped is no as thick as the rest, some times only 2 or 3 inches are left, some times crack , if the grading is high enough in the area, will create a leak.


Block or stone foundations are a complete different ball game. Injection in a block foundation is not recommended. First you have to find the source of the problem, some times a plugged weeping tile creates a water table and the hydrostatic pressure builds up and forces the water through the joints or block. My first recommendation is to send the camera in to determine the problem, a broken weeping tile, older houses have clay ones, a plugged one (roots, mud, etc). If the wiping tile is just plugged, it can be clean with a snake or appropriate pressure water hose (a entry point has to be find first). Then if the problem is just aging of the components, a waterproofing is required. The entire perimeter of the house has to dug out , water pressure wash of the exterior walls, primer is applied to allow self adhesive elastomeric bitumen membrane (1.5 mm thick) to stick to exterior of the foundation. This membrane is flexible and covered with high density polyethylene film. On top and covering the entire surface of the foundation another membrane is installed (made of tough, durable high density polyethylene) mechanically fastened to the foundation.The dimpled construction of this membrane will keep wet soil ¼ inch away from the foundation.