Foundation Waterproofing

Foundation waterproofing is one of the best investments you can make when building.  If your new home will have a basement, building codes typically require the foundation to have some type of dampproofing on the exterior of the wall to keep moisture out.  The minimum code requirement is typically a tar material that covers the surface of the concrete.  The problem with the tar is it gets brittle and has very little elasticity to it.  So, when the wall moves and/or cracks, the tar cracks along with it.  This leaves the basement susceptible to groundwater intrusion. 

Foundation Waterproofing with Insulation Board

According to the 2012 International Residential Code, foundation walls that retain earth and enclose interior spaces and floors below grade shall be dampproofed from the top of the footing to the finished grade.  Masonry walls shall have a minimum of 3/8 inch Portland cement parging applied to the exterior surface of the wall.  On top of the parging, a dampproofing will be applied with one of the following methods…

·         Bituminous coating

·         Three pounds per square yard of acrylic-modified cement

·         1/8 inch coating of surface-bonding cement complying with ASTM C 887

·         Waterproofing as permitted in section R406.2 (2012 International Residential Code)

It’s important to check with your local building department to find out what their specific requirements are for the exterior of foundation walls.  If you aren’t using a masonry foundation wall, there are typically different requirements (there too many types to mention here).

So, what is a better alternative to basic dampproofing for a basement wall?  If you ever plan on finishing your basement, you will most definitely want to use a waterproofing material.  These materials have an elasticity that allows them to bridge any gaps you will get in the foundation wall.  The bridging prevents water from penetrating the cracks, keeping your basement dry.  As always, it’s very important to carefully read the manufacturer’s recommendations and application requirements to make sure the warranty will be valid.

Another product that will help prevent water from penetrating your basement wall is an exterior insulation board.  Not only are these boards designed to provide an insulation R-value to your basement but they also provide a drainage plane to keep water from being trapped up against the foundation wall.  If the water doesn’t have a chance to stagnate against the wall, it will have a difficult time penetrating the cracks and voids.

The insulation board, shown in the picture above, will also protect your foundation during backfill operations.  Rocks and debris can cut through dampproofing and waterproofing material which can cause future leaks.  With the insulation board, your wall has an added layer of protection that helps prevent this damage.

So what does foundation waterproofing cost?  There are so many options available, it can be difficult to estimate without specifications.  As a builder I can tell you the difference is well worth the price.  The average American home can be upgraded to waterproofing on the outside of the foundation wall for as little as $500 to $1000.  Keep in mind, the application of the waterproofing needs to be done either way,  so the labor cost is the same.  The only difference is the cost of the material.  And since waterproofing typically goes on thicker, it costs more than the dampproofing.

So, be sure to ask your builder or contractor what they would use to waterproof their own basement if they were building today.  Take the time to investigate some of the products on the market and see which best suits your particular home, lot and subsurface conditions.  Also be sure to let your contractor know if you are planning on finishing the basement sometime in the future.

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Michael Luckado

Michael Luckado has built, remodeled, and repaired thousands of homes across the U.S. He co-founded ArmchairBuilder.com to help people save money and time creating their dream home.

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