How Important is Deflection To Foundation Performance?

Performance indicators

TREC includes a list of foundation performance indicators in their Standards Of Practice For Structural Systems. One performance indicator is this: sloping floors. The TREC Standards of Practice offers no insight as to how much importance should be assigned to sloping floors. The same is true regarding all of the TREC indicators.

Slab-on-ground foundations serve as a floor. They are designed and constructed to mitigate any distress or damage to the foundation itself or to the supported wood-frame structure. Notice: the keyword is “mitigate”, not “eliminate”. There is a reason for this: we simply do not know how to build an affordable house that people will buy and that will not show distress during the life of the house. 

Foundation repair indicators

I know of nothing issued by TREC or the TBPE that could be called a repair indicator. There is some wording in a document titled the Texas Section – American Society of Civil Engineers in document title be performance indicators. This guideline states that if there is a structural integrity issue, then foundation repair is not optional. Meaning that foundation repair is mandatory.

I would state this differently. Foundation repair is required if there is:

(1) there a structural integrity or safety issue

(2) there is a defensible explanation  of how foundation repair can correct the problem

(3) foundation repair is cost-effective as compared to other possible options.

Estimating slab-on-ground foundation deflection 

Deflection, also known as bending, is an important part of assessing the performance of a slab-on-ground foundation. Having said that, it is not the most important aspect of foundation performance.                 



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