Basement Leaks

Basement Leaks

How to find the source of basement leaks and determining a repair

Basement water ingress and moisture issues are most likely caused by defects in the concrete.
Concrete is a porous building material that is able to act as a waterproof barrier with enough structural integrity and mass.
Cracks, construction joints, honeycombing and form tie holes can cause leaks through concrete. Sitting water, poor drainage, and past localized repairs can cause moisture issues by trapping water within concrete.
If you suspect a leak within your basement, it is best to remove a section of drywall to inspect the concrete (or have a qualified contractor do it for you).
Trust the professionals at Miller & Co to ensure the basement leak repair materials and procedures are going to last!

How to find a basement leak?

Sometimes moisture trapped in a wall makes it hard to determine the source right away. Allow trapped moisture to dry, then follow the path of new moisture as it occurs. To speed up this process, a flood test can be done by running a hose at the exterior. This should be avoided if possible as to not flood the area any more than necessary. If performing a flood test, monitor the interior closely and have someone ready to turn the water off quickly.
Cracks and construction joints are the most common source of leaking. If you find a crack or joint, continue removing drywall until there is a clear beginning and end, this will likely be the extent of our repair work.
It is also possible to observe the outside of the building for cracks in, as most foundation walls have at least a few inches exposed on the exterior.

Why do below grade basements leak?


Rainwater that saturates the exterior landscaping or run off the surface can leak into vertical cracks and other defects in the wall. Despite being the most common source of water, and is often ignored by inexperienced contractors. Assuming that water on the basement floor, has come from the basement floor ignores that gravity will pull any leaking water downward.


If a basement floor is leaking, then it will be caused by rising groundwater. Rising groundwater causes major basement issues. Water will enter the home starting with wide floor cracks, perimeter construction joints, and then fine cracks.
When groundwater is an issue both sump pumps and localized or full waterproofing are recommended. Please be advised that hiring a contractor to seal a basement floor without removing studs and sealing the construction joints is a recipe for disaster if no additional drainage measures have been introduced.
Ensure that any sump pump’s basins that are to be installed on site are a Crawlspace model, and not a Sewage model. Sewage models are water tight and will not divert water under a slab into the drainage system.

What is the best basement leak repair system?

  • Localized defects can be economically repaired from the inside of the home. When repairing concrete, you want to ensure that the work is not going to trap water and cause high levels of moisture or lose effectiveness over time.
  • Crystalline waterproofing or hydraulic cement are often used as they are readily available to the public. These products tend to trap water within the substrate, and cannot resist cracking due to minor movement. These materials can applied quickly and easily to reduce the impact of water damage but should be used in conjunction with a permanent repair solution.
  • Urethane injection materials can make a great temporary water stop, and are also very common and easy to obtain. Material selection is critical based on the environmental conditions of the repair location. Improper materials can shrink over time allowing your leak to return. It is critical to ensure a guaranteed permanent solution is performed when interior finishes may be affected. If using urethane, ensure a well known and trusted company is used as poor urethane repairs can double or triple the total project cost.
  • Sometimes drainage and waterproofing are so poor that a localized repair to the concrete will not suffice. In these cases excavating the exterior followed by re-waterproofing is required. Waterproofing applications must be done during dry weather, to allow for the material to bond . Miller & Co will recommend full exterior waterproofing whenever moisture saturation of the concrete is high, often visible by large areas of efflorescence or organic growth.

Basement Leak Repair Health & Safety Disclaimer

Customers trust repair providers to never endanger their personal health and safety. Residential customers are often passionate about supporting small and local companies. Please consider performing due diligence on the products that will be used inside your home by requesting and reading both the TDS and SDS.
” Asphalt, also known as bitumen is a sticky, black, highly viscous liquid or semi-solid form of petroleum “
Bitumen products often contain an very high amount of VOC’s and even when inert can emit a foul odour within the home.
Residential coating contractor’s material of choice is a decorative flake system. These systems often include a 85% solids polyurea/polyaspartic due to the ease of installation for the installer. The solvent in these products emit dangerously high levels of VOC’s into your home, where they can linger for long periods of time. Products labeled low odour and low voc also state installers must wear full faced chemical respirators. If a solvent odour is observed, you are already well past the recommended safe exposure limit. The solvents in these products are extremally dangerous to pregnant and breastfeeding women, and children.