Are Crawl Space Foundations the Cause or Solution to Foundation Problems?

August 7, 2011 Melanie Chaney

Most builders love crawl space foundations, and they have good reasons for choosing this type of foundation over other options. A crawl space foundation requires much less excavation work than a full-height basement foundation, so there’s less disruption and impact on the building site. This is a major advantage when homeowners decide to have an addition built on an existing house.

Advantages of Crawl Space Foundation

  • Minor Disruption –Today, most basement foundations are built using poured concrete. But the shorter walls of a crawl space foundation can be built quickly from concrete blocks. Again, this is usually less disruptive to the building site than having a large concrete mixer drive over the lawn.
  • Speed –Excavation can be done quickly, there are no forms to erect, and there isn’t much backfilling work to be done once the crawl space walls are built.
  • Low Cost –Less excavation, lower material expenses, faster construction time, and the economy of a dirt floor inside the crawl space walls; all these factors make the crawl space a very economical way to “get out of the ground,” as builders say.

Crawl Space Complications

The money saved by choosing a crawl space foundation can be spent in other areas where homeowners want “wow” value –like hardwood floors and high-end cabinetry. Once the building is completed, the dark, damp, dirt-floored crawl space is out of sight and out of mind.

Here’s the problem. As time passes, a vented, dirt-floored crawl space is certain to come back to haunt unsuspecting homeowners, causing problems ranging from mold and rot to poor energy performance, settling floors and health issues.


The dark, damp interior of a crawl space creates a perfect environment for mold to grow on wood and on the paper backing of fiberglass batts installed between floor joists. Mold spreads via airborne spores, so it’s easy for spore-laden air to enter the living space above through holes made for plumbing pipes, electrical wires and ductwork. When this happens, family members are likely to suffer from allergy attacks and respiratory ailments.

Decreased Insulation Efficiency

Crawl space moisture diminishes the R-value of fiberglass insulation and can even cause batts to fall out of place as they become wet. Sheet metal ductwork in the crawl space can rust, and ductwork that isn’t insulated or sealed will waste energy and possibly allow crawl space air to be drawn into the ductwork system and distributed in the living space.

Structural Rot

Structural problems can develop if joists succumb to rot. Crawl spaces can also have problems with the beam or girder that extends down the center of the foundation to provide mid-span support for floor joists. Wood posts and concrete blocks installed to support this beam sometimes shift or settle, causing the floor (or sections of it) to dip down in the middle.

Expert Foundation Repair

Despite all of the potential problems mentioned above, a crawl space can be a solid, safe and energy-efficient foundation if proper improvements are made by a contractor who specializes in foundation repair.

Our Solutions

Crawl Space Encapsulation – The dirt floor is sealed with a continuous moisture barrier, and waterproof rigid foam insulation is installed against foundation walls to provide superior insulation value while also serving as an air barrier. Installing gasketed airtight covers over vent openings eliminates the adverse effects of pests and outside air while still providing crawl space access.

Replace with Steel Posts – Foundation repair experts can also replace inadequate support posts with adjustable steel posts that extend from secure precast concrete footings. This structural upgrade makes it possible to straighten and stiffen sagging floors.

Contact Baird Construction Co., LLC for a free estimate for foundation repair in San Antonio and surrounding areas.

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