For now, we will address only the reference to accepted industry practices. We tackle consideration of age and normal wear and tear on another page.
Accepted industry practices applicable to foundation performance
How to apply the phrase accepted industry practices to foundation performance is not unambiguous. There are inspection items for which the application of this phrase is clear. Examples are ground fault devices and electrical breakers. Accepted industry practices certainly includes the National Electrical Code and the manufacturer’s instructions. This is not the case with foundation performance.
The codes specify how slab-on-ground foundations shall be designed, not how well or poorly they are expected to perform.
If you look at the code-approved design methods from an engineering perspective, it is certainly possible to infer from the design manual what a structural engineer would expect regarding the performance of a slab-on-ground foundation. Unless a home inspector had some training in engineering or was self-taught in reinforced concrete engineering design, a TREC home inspector would probably not infer anything regarding performance. The fact is, while a good understanding of foundation design for expansive soils is helpful to engineers, that is not the case for either real estate agents or home inspectors.
If not the codes or the design methods, what else might the phrase accepted industry practices refer to? Elsewhere in this site, we discuss a wide array of accepted industry practices that, in our opinion, meet that description. For purposes of this article, we want to concentrate on four pieces of published material that qualify as accepted industry practices and are, in our opinion, reliable. Those four are listed below:
The TREC SOP
The TREC SOP is certainly the one authoritative source you should be familiar with.
ARMY Corps of Engineers publication: Foundations in Expansive Soils
This document has a very useful chapter (chapter 9) on remediation. It is short, straightforward and not overly technical. It is available online and it’s free.
Texas Section ASCE publication: Guidelines for the Evaluation and Repair of Residential Foundations, version 2
This is another document written for engineers. It is long but includes good and valuable advice. Every TREC inspector should have a copy and read it often. It is available for free online.
Guide for Performance Evaluation of Slab-on-Ground Foundations
This is a guide published by the Post-Tensioning Institute, the same organization that publishes the manual used for designing slab-on-ground foundations. This guide is explicitly intended to be used for both post-tensioned and conventionally reinforced slab foundations. In many ways, it is similar to the guideline published by the Texas Section of the ASCE.
The main difference is that the document does not address foundation repair: when foundation should be recommended and when not recommended.
So Your House Is Built On Expansive Soils
Published by the American Society of Civil Engineers (ASCE). It is not really a book; it is closer to a booklet at less than 60-pages. It was produced by the Shallow Foundations Committee of the ASCE headed by Warren K Wray, Ph.D., PE.
Wray’s Ph.D. dissertation formed the basis of slab-on-ground foundation design as it is practiced today.
This booklet is addressed to homeowners who live in areas where expansive soils is an issue. The ASCE has let the booklet go out of print. r The booklet is very hard to find at a reasonable price. Fortunately, my son and I took the booklet and we wrote a version focused on Houston and southeast Texas. Our version is a free printable pdf file.
Has Your House Got Cracks? 2nd edition
This is a British publication. It is excellent. It is similar to the American publication titled: Has Your House Got Cracks?, 2nd edition. The biggest difference is that, in the United Kingdom, distress and damage due to expansive soil movement are covered by homeowner’s insurance. Not so in the United States.
Standard engineering textbooks
There are numerous engineering textbooks on soil mechanics and foundation design. Some include a discussion on what is meant by foundation performance. An excellent example is, in my opinion, chapter 2 in Foundation Design – Principles & Practices by Donald P. Coduto.
Coduto stresses the importance of how a foundation is expected to perform as compared to how it is performing.