Dealing With Leaky Basement Walls

Leaks and squeaks are two of a contractors worst nightmares. They also can drive homeowners bonkers. Fortunately, with patience and persistence, the source of most leaks and squeaks can be located and repaired.

Although a squeaking floor can be irritating, it is insignificant compared with damage that an undetected leak can cause. Water is the greatest threat to any home. In light of the El Nino toll, we’ll discuss leaks in this column, and leave squeaks for another day.

A basement is a prime location for leaks. The fact that it is below grade (ground level) makes it especially susceptible. This is true whatever its construction. All types are subject to leaks whether they are of block, brick or poured-in-place concrete.

Basements leak for many reasons. Surface run-off due to poor grading, lack of or defective gutters and downspouts, blocked drainage at the base of a home’s exterior walls and a defective or missing footing drainage system are a few.

Proper grading is important. The soil surrounding the home should drain AWAY from the foundation. The grade doesn’t need to be extreme, just enough to keep the water running in the right direction. This should be done for a minimum distance of three feet from the foundation.

Along with good grading go gutters and downspouts. If your home doesn’t have them, install them. If they exist and are leaking or clogged with debris, clean and repair them. A garden hose with a high-pressure spout along with a high-quality caulking compound is all you’ll generally need.

A good watershed system doesn’t end with gutters and downspouts. Downspouts should discharge into solid drainpipe that will carry the water away from the home into non-erosive material or a municipal storm drain system.

A footing drainage system (French drain) will collect subsurface water and relieve hydrostatic pressure. The latter is a phenomenon that results from groundwater pressing against foundation walls. This pressure can be so intense that it may pop out the joint mortar between concrete blocks or between the walls and the floor.

The footing drainage system consists of a perforated pipe surrounded by a belt of gravel. The system is located at the base of the footing at the perimeter of the house. Periodically the drainage system will need to be flushed with a garden hose to remove silt and clogs.

Aside from the elements listed above, the key to a dry basement is a sound waterproof membrane at the exterior of the basement walls and floor. There are various waterproofing materials including a built-up asphalt system, single play membranes and other impervious systems. These membranes typically are applied to the exterior surface of the basement walls during construction.
Prior to backfilling the area surrounding the basement with soil, you should protect the membrane from potential damage using rigid foam, landscape fabric or a combination of the two.

Maintaining proper grading and installing and maintaining gutters, downspouts and a drainage system are reasonably easy, inexpensive tasks that can be done by most homeowners. On the other hand, installing a French drain is a project best left to a professional. Before attempting to install a French drain, you should have the system designed by a soils engineer.

If after employing our suggestions, you continue to experience basement leaks, there are measures that can be taken on the interior to resolve the problem. Most often, water enters a basement through cracks or mortar joints between concrete blocks.

The first step in the repair process is to chisel the crack wider to create space for patch material. This is done using a chisel and a small sledgehammer. A continuous flow of water from the crack indicates high ground water or intense hydrostatic pressure. This condition should be relieved before proceeding with the repair.

An effective means of relieving this pressure is inserting a “bleeder tube” into the crack. This is a temporary drainpipe made of iron, copper or rubber. The tube should discharge into a bucket.

Next, with the bleeder tube in place, fill the crack with hydraulic cement. Use a trowel to pack the material into the crack. While the hydraulic cement hardens, form a stiff hydraulic cement mix into a plug. Pull out the bleeder tube and force the plug into the hole. Smooth out the plug and hold it in place with the trowel until the cement hardens.

Although most waterproofing is done from the exterior, or “source side” of a wall, there are some after-market applications that can be used to combat damp or wet walls. They are especially useful when waterproofing from the exterior is neither possible nor practical.

One such method that has been used primarily for industrial and commercial applications is becoming popular for residential use. The system is called XYPEX Concrete Waterproofing by Crystallization.

Xypex consists of portland cement, very fine treated silica sand and various active proprietary chemicals. When mixed with water and applied as a cementitious coating, the active chemicals in Xypex cause a catalytic reaction that generates a nonsoluable crystalline formation of dendritic fibers with the pores and capillary tracts of concrete. Thus, the concrete becomes permanently sealed against the penetration of water or liquids from any direction.

For more information on Xypex, contact the manufacturer, Xypex Chemical Corporation at 1-800-961-4477.

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