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How to Waterproof a Basement with a Brick Foundation

May 10, 2014 • By Matthew Stock.

Brick Foundation

Brick has been around as a building material for a long time with the first bricks showing up around 9000 years ago as sun-baked blocks of mud.  The Roman Empire gave us kiln-fired bricks made of clay and sand and it is this type of brick that has, in one form or another, endured as a versatile construction material.

There are, of course, bricks made of concrete but these are used primarily as a paving and hardscape material, turning up in driveways, patios and other outdoor structures.

Today, brick usually performs a decorative function in residential construction, laid as a veneer over frame construction.  In earlier days, entire homes were built of brick as were all or part of the foundations they sat on.  These foundations may have been built up to ground level with concrete block or stone and then finished with brick for the sake of appearance or may have been built with brick walls all the way down to the footings.

These full brick foundations certainly bore the weight of the aboveground structure as well as any other but the numerous mortar joints and natural porosity of bricks often led to basement water problems.  There are several effective, permanent waterproofing techniques to keep these basements dry.

How to Waterproof a Brick Foundation

The most common source of seepage in a brick foundation wall is a mortar joint.  Since most brick foundations are old the mortar has had decades to deteriorate or crack from minor foundation movement.  Also, lateral pressure from over-saturated soil outside can cause significant cracking in the wall.

Also, old clay bricks, even though they were kiln-fired, are somewhat porous and water will eventually seep through the brick itself and may eventually cause the brick to deteriorate.

Unfortunately, cracks in mortar joints cannot be injected with expanding polyurethane like seeping cracks in poured concrete walls.  It is possible, however, to waterproof a basement with a brick foundation from the inside.

Interior waterproofing for a brick foundation wall starts with installing interior drain tile, a system of perforated pipe buried in washed gravel under the basement floor.  When the basement floor is repaired after installation, a small gap is left between the floor and wall.

The seepage will then trickle down the wall and into the drain tile system where it is collected and carried off to a sump pump.  Installing a vapor barrier is recommended to cover the signs of seepage and contain moisture.  The interior drain tile will also collect and remove water that would otherwise seep through floor crack or through the cove joint.

The most effective method, however, of waterproofing a basement with a brick foundation is done on the exterior.  The process begins by excavating along the wall, all the way down to the footings, leaving a trench big enough for a technician to work.  Dirt, loose mortar and brick dust are scrubbed off the wall and a “parge” coat of mortar is applied over the entire wall that provides a more uniform surface.

Once the parge coat has cured, an exterior waterproofing membrane consisting of asphalt-modified polyurethane will be applied with a trowel in a thick coat to the entire wall.  If ground water is particularly high, exterior drain tile will also be installed and the membrane will be covered with heavy-duty plastic drainage board that will protect it and channel water down to the drain tile.

The excavation is then back-filled and the repair is complete.

No matter which repair method is recommended, a homeowner with a brick foundation will require the assistance of a basement waterproofing contractor with experience in working on homes like his or hers.  At U.S. Waterproofing, we have been keeping basements dry all over Chicago and surrounding areas since 1957 and have permanently waterproofed foundations of all types, including many of brick.  Why not ask for our free advice?

If you have questions about waterproofing a basement with a brick foundation, please post them in the Comments box below.

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