Should I Build on a Pre-existing foundation / by Keith Moehle

A lot of homeowners would like a quick fix to get more square-footage by building on a pre-existing foundation, but this can be a recipe for disaster.

We wish that it could be as easy as building on pre-existing foundations, but there are several hurdles we have to go over before we start the process (if it is even possible.)

Screen Shot 2018-06-13 at 9.06.50 AM.png

Here are a few of the issues that we typically run into:

  • The foundation may not be high enough to keep water out.

  • Your foundation may not be waterproof. This means there is not a moisture barrier to prevent water from coming up from the ground into the newly built room which will result in mold and other issues.

  • In most cases, it is not structurally sound so it may be sloped and have lousy drainage.  

  • If you live in the City of San Antonio, you will have to have an engineer sign off on a letter stating your pre-existing foundation will be able to withstand all of the materials that will be on it. It will be tough to get an engineer to sign off on a letter if there is no way of knowing how the foundation was built.

It is a lot cheaper to enclose a pre-existing foundation, but in the long-haul, you could be paying a hefty price for trying to get a quick fix to more square footage.

Get more square-footage the right way by calling Keith up at 210-680-5626 to see what path we have to take to start an addition!



----KM Builders is San Antonio’s premier design-build remodeler specializing in kitchens, bathrooms, room additions and whole-house remodeling. We boast the largest in-house staff in San Antonio offering architectural design, interior design, and cabinet design for all your home remodeling needs!