How to Build a Basement That Stays Dry

It’s that time of year again.  The snow is starting to melt, and heavy spring rains are on the way.  These bring with them the unfortunate wet basement.  Now that you are creating your dream home, it’s time to include best practices in your planning to prevent future hassles from water in your lower level.  Let’s take a look at some of the best advice for building a dry basement.   

Drainage Plane

This is a builder term that everybody building a home should get familiar with.  Whether you are building a home with a poured foundation or going with a block, cracks are inevitable.  One way to prevent foundation cracks from causing a leak is to get water away from the foundation wall as quickly as possible.  A properly designed drainage plane will achieve this.  The easiest way to describe a drainage plane is to share a few examples.

• Stone – Using a stone backfill up against the foundation wall will allow water to flow freely down to the drainage system below.
• Insulation Board – Many of the exterior wall insulation boards also serve as a drainage plane.  The water trickles down through the air pockets in the board down the wall.
• Drainage Mat – These products come in rolls and are applied up against the exterior surface of the foundation wall.  The geometry of the material creates voids once the wall is backfilled that will allow any water present to move down the wall.

By creating a free-flowing drainage plane at the exterior surface of the foundation wall, the water won’t have time to accumulate and work its way through small cracks into the basement.

Waterproofing

A good waterproofing material is essential for building a dry basement.  Most building codes only require a thin damproofing material that can dry out and crack over time.  A quality waterproofing material will keep its elastic properties over time to allow it to span cracks that form in the foundation wall.  Look for a material that has been around for several years and comes with a minimum of a five-year warranty.

Regarding the warranty, make sure the manufacturer stands behind the labor and materials of the installation.  I built a home about ten years ago and used a high-end waterproofing material for the basement foundation.  Unfortunately, the installer didn’t do the best job, and we had a leak.  After trying for several days to make contact with the waterproofing contractor, I learned they had gone out of business.  Fortunately, the manufacturer stood by their warranty.

Drainage System

Once the water that accumulates around the foundation safely makes its way down to the footing, it’s time for the drainage system to take over.  A properly designed drainage system will collect this water and transport it safely away from the foundation.  There are so many different types of systems used in new homes today.  However, the traditional drain tile system still works.  It’s made up of a pipe, either corrugated with slits or hard pipe with holes facing down, stone covering, and some form of protection to keep the silt from clogging the pipe.  This protection can be a mesh sock surrounding the pipe or a filter fabric placed on top of the stone above the pipe. 

Grading

One of the simplest components used when building a dry basement is a proper grade around the home.  A well-designed and implemented final grade will direct surface water away from the foundation.  Typically, building codes require the grade to drop a minimum of six inches for the first ten feet around the home.