How Do I Seal a Leaky Basement?

A leaky basement is a source of concern, moisture can not only ruin wood, drywall, and carpets, but it also creates mold.

Can I Fix a Basement Leak? Can I Fix a Leaky Basement?

As frustrating as this answer is, it really depends on the cause of the leak.

What are the most common reasons for basement leak?

Roof water

Many homeowners aren’t aware of the importance of exterior water placement. If a home’s eavestroughs and downspouts are not properly cared for, they can cause many issues in the home, including a leaky basement.

If you are experiencing water issues in your home, take a quick look at your eavestrough and downspouts. Make sure they are cleared of debris and pushing water away from your foundation walls.


Some homeowners experience basement leaks from over watering the flowerbeds and shrubs around their home. Make sure you are not creating pools of water near your foundation walls, as it will increase your chances of a leak.


Unfortunately, there are some things that we can’t control, and groundwater redirecting itself towards your home is one of them. Pooling water may be caused by nearby landscaping changes; however, it can also be caused by a natural environmental adjustment.

Another issue that can be caused by groundwater is the build up by capillary action. If white residue is seen on the floor, capillary action is usually to blame. These white spots are caused from mineral deposits left after water evaporation.

Sub-grade shifts can create pooling water along your foundation wall, which will slowly seep into your basement. If your home suffers from any of these symptoms, it is highly recommended you call in a waterproofing professional. A leaky basement does not only increase the risk of mold and airborne spores, it also threatens the structural integrity of a foundation.

Snow and Rain Runoff

If snow or rainwater collects in depressed areas, there is a high chance it will make its way into your basement. To prevent this, walk around your home and change/ fill-in any holes with pooled water/snow.

Damaged Drains

If your drain is improperly installed, damaged, or clogged, you can experience a leak in your basement. It is important to make sure your drains are properly working, so unnecessary work is not purchased.

Another drain issue that homeowners can suffer from is un-sloped underground drains. If your underground drains do not have a big enough slope, build ups and leaks will occur. These drains are very important as they keep basements dry and reduce moisture build up on your foundation.

Broken lines

Water and sewage lines can get damaged. This is an uncontrollable issue, as it can occur from deterioration or earth pressure. Tree roots can also penetrate the pipes, creating leaks.

No Ventilation

Air circulation is very important for a basement. If air can’t circulate, humidity will build up inside the structure, causing water issues.

How to check if my basement water issues are a leak or humidity?

If you want to determine if your water issues are Leak or Humidity related, tape a 1’ square of aluminum foil on you wall and leaving it overnight. If you find condensation on the room side of the foil, you know it is humidity that is causing your problems (The aluminum facing away from the wall). If moisture is on the wall side, it means you have water coming in from the outside of your home.

How can I Fix a Basement Leak? DIY fixes for a Leaky basement.

1. The first thing to do is fill all cracks and gaps under 1/8-inch wide with polyurethane caulk (Use the one specifically made for concrete).

Use epoxy filler on cracks and gaps that are larger than 1/8 of an inch wide.

2. Next, you should choose one of the many commercial products made to seal cracks.

These products include:

  • Concrete waterproof coatings

  • Silicate-based sealers

  • Waterproofing paint

  • Interior water-control systems

3. Add your waterproof coating to the filled crack

  • Concrete waterproof coatings should be placed on top of finishes.

  • Silicate-based sealers are intended for untreated surfaces, as they chemically react with bare concrete.

  • Waterproofing paint is a heavy latex paint used to seal the wall with an acrylic layer.

4. Interior water-control systems

Wall vapour barriers and drip moldings are used to collect water that enters through foundation wall cracks. By using this system, and placing a drain along the footings, water will be directed to a sump pump and pushed out of the home.

While a DIY homeowner may attempt this, it is an extensive project that requires proper detailing. If a DIY method does not work, or you can’t access your basement walls to do the repairs, you will need to call in a contractor.

They will excavate around the foundation, seal the leaks, and wrap the foundation in a waterproof membrane. New weeping tiles are placed near the foundation, and the soil is backfilled. If you are still having issues controlling water, it may be necessary to install a sump pump.

It is always better to call a professional sooner rather than later. Water damage can be expensive, and the long-term effects are cumulative.

If you are in need of proper waterproofing supplies, check out the Waterproofing Warehouse

About Nusite

Nusite Contractors Ltd. has been proudly serving GTA homeowners for over 30 years! We are a family business and take pride in customer service and professional work. You can contact us here to schedule a free consultation and written estimate! We would be happy to help!

#NusiteContractorsLtd. #Waterproofing #GTAWaterproofing #FoundationRepair #ConcreteRepair #ConcreteContractors #FoundationSpecialist #WeCare #Tips

Call or Message Us for a Free, No-Obligation Estimate. We are Happy to Help With All Your Waterproofing or Concrete Needs.