What The Texas Section ASCE Says About Elevation Measurements

What is the Texas Section ASCE?

The ASCE stands fo: the American Society of Civil Engineers. The Texas section is the Texas arm of the ASCE.

What is a profile?

     

 

   

 

A single set of elevation measurements has limited value

A single floor level survey yields the shape of the foundation at one instant, and may or may not furnish sufficient information to support a conclusion. An evaluation may include repeated floor level surveys performed over months or years. In such cases, the change in shape is measured between surveys. In addition, previous foundation repairs may change elevation shapes.      

Case 1: If the elevation measurements across a profile suggest that the deflection ratio is less than 1/360, …”it is unlikely the foundation is deflected materially unless visible indications show otherwise.”

Comment: You might wonder: what does the statement – unless visible indications show otherwise – mean? I would contend that if a slab-on-ground foundation bends in excess of 1/360, there should be diagonal drywall cracks, stair-stepped brick veneer clacks, and sticking downstairs doors.

Please note also that, even if the deflection is excessive, there is no indication that foundation repair should be recommended.

In addition, there is nothing magical about a deflection ratio of 1/360. It would be very unusual for a foundation with a deflection ratio in excess of 1/360 to have any structural integrity or safety issues. What distress would be a result of deflecting to a deflection ratio of 1/30 could easily be repaired using normal repair techniques.   

Case 2: If a foundation profile indicates the deflection ratio is more than 1/360, and minimal symptoms of deflection are present, then additional information is needed by the engineer to develop a conclusion. The additional information may allow the engineer to determine whether or not the foundation has deflected excessively.

Comment: 

Case 3: If a foundation profile indicates the deflection ratio is more than 1/360, and sufficient symptoms of deflection are present, then the engineer generally will be justified in determining that the foundation has deflected excessively.

Comment:    

 

 

Print Friendly, PDF & Email