Foundation Investigations: When is one needed?

Texas has large areas with clayey soils that shrink and swell with changes in soil moisture content (expansive soil), see map.The shrinking and swelling of the soil will lead to movement of foundations that placed upon the soil (majority of foundations). Excessive movement of the foundation can lead to distress phenomena such as cracks in brick veneer, drywall and concrete as well as separation of trim, sticking of doors and noticeable slope in the floor. If you notice these distress phenomena it is best to consult with a structural engineer quickly since they can be indicative of an issue with either the foundation design/construction, drainage,  or landscaping that are leading to poor foundation performance.

Texas Expansive Soil Map
Texas Expansive Soil Map

Levels of Foundation Investigation:

There are varying degrees of foundation investigations that can be conducted. Deciding upon which level is appropriate for the specific circumstances of project should be jointly established and agreed to by both the Client and the Engineer. The two most common level of investigation are Level A and B, which are defined below.

Level A Foundation Investigation:

Level A Foundation Investigations include…

  1. Interview the occupant, owner and client if possible, regarding a history of the property and performance of the structure
  2. Request from the client and review the provided documents regarding the foundation, such as construction drawings, geotechnical reports, previous testing and inspection reports, and previous repair information
  3. Make visual observations during a physical walk-through
  4. Observe factors influencing the performance of the foundation
  5. If requested by the client, provide a written report, containing at least the following: a. scope of services b. observations, site characteristics, and data deemed pertinent by the engineer c. discussion of major factors influencing foundation performance and rationale in reaching conclusions concerning the subject residence d. conclusions and any recommendations for further investigation and remedial or preventative measures

Level B Foundation Investigation:

Level B Foundation Investigations includes all the items from a Level A plus the following:

  1. A determination of relative foundation elevations in sufficient detail to represent the shape of the foundation or floor adequately.
  2. A drawing showing relative elevations. See below for example of drawing showing relative elevations with contours.

The benefit of having a Level B investigation is that is provides a measurable data point that can be used in collaboration with observed distress phenomena to determine if excessive foundation movement has occured.

Foundation Elevation Contours

Typical Fee Structure for Foundation Investigations

Our fees for foundation investigations typically fall under the fee structure below. Our fees are generally higher than other professional engineering firms which we believe is justified by our expertise, client service and history of successful projects. We typically provide more in-depth reports that include analysis and recommendation to mitigate or remediate foundation issues.

Foundation Assessment Fee Structure

Experts in Foundation Investigations

Dudley Engineering has established itself as one of the premier resources for identifying, mitigating and remediating foundation issues across Central Texas. We have done this by immersing ourselves in the research, case examples and our own field experience. See links below for articles we have authored on the subject.

Insite Magazine – Residential Foundations in the Brazos Valley

Greater Houston Builders Association: Residential Foundations in Montgomery County