Keeping Your Basement Dry Requires A System
By: John A Knoelk
Spring Showers bring more than May flowers, they bring leaky basements too. Let's explore the construction of the typical basement wall and the best solutions for stopping leaks, understanding that keeping water from your basement requires a system, and if any one part fails you can have leaks.
In the Midwest, basement walls are almost exclusively constructed from poured concrete. This concrete is poured in between forms which are typically held together by metal rods running through these forms. Once the concrete sets the forms are stripped away and the rods are snapped off flush with the concrete walls, the majority of the rod remaining in the wall.
The First part of the system is coating the foundation walls. Typically the walls are damproofed, the area where each rod remains is spot patched with tar and then the entire wall is covered, often times by spraying with tar like coating. This is called damproofing, not to be confused with waterproofing. Understand that this damproofing is a part of the system that keeps water from infiltrating your basement. The second part of the system is the drain tile. This is a 4" perforated corrugated flexible plastic pipe that is laid outside and alongside the footing (bottom of the foundation wall) typically in a loop ending at an enclosed pit that collects the water. When the water reaches a certain height in the pit a submersible pump then pumps the water out and away from your house. In some areas this drain tile is also installed inside the footing and routed to the same pit.
A third and equally important part of this system is the proper grading of the ground surrounding your home. The ground should be gently sloped away from your home on all sides. Driveways and patios that have sunk over the years and now slope to the building are a delivery system for water into your basement.
When it rains the majority of the water should follow the slope away from the house. The remaining water will find its way down through the soil to the drain tile which gathers it and carries it to the pit where it is pumped up and away from the house. Problems occur when water runs down against the foundation and finds a crack or a rod that was not patched or after years of exposure has rusted sufficiently to allow water to travel alongside the rod, and into your basement.
Originally the foundation was sealed on the exterior subsequently all surface type repairs should be completed from the outside, which entails a lot of digging and landscape issues. Enter the epoxy repair. The repair crew will work from the inside and begin by cleaning out the crack. Starting at the bottom of the crack they will inject an epoxy into the crack moving injection points upwards approximately 12" at a time until it is full. This method is designed to stop the water before it gets near the inside of the wall and typically will come with a lifetime guarantee.
Another method that is employed is allowing the water to leak through the wall and immediately catching it in a membrane which is placed around the perimeter of the wall. The water is then channeled into a pit where it collects and can be pumped out. You will see this technique used a lot on older foundations where you have multiple leak points.
Lastly the most expensive remedy but far superior is waterproofing the exterior with a rubber membrane or a blanket that has a type of product that expands and blocks water infiltration when it becomes wet, such as a Bentonite blanket. Of course this type of repair requires the entire exterior of the foundation to be dug up down to the drain tile which can now be inspected, repaired, and/or replaced as needed. The foundation is cleaned of any dirt clinging to it, pressure washed and inspected from the outside. Spot repairing any suspect areas should be completed after inspection and then the blanket or membrane is installed. The wall is then backfilled with dirt compacting as you go. The landscaping should not be reinstalled no matter what the visual condition of the ground is, for a minimum of 6 months, because the ground will settle, sometimes dramatically.
Knowing the wet basement solutions will help you keep your basement dry.