Some foundation repair contractors will, for a fee, provide the homeowner with a letter from a Texas Professional Engineer that certifies that the repair work on your house was done to some standard. Most of them simply state that the engineer reviewed the repair plan and that it a typical repair plan. The plan is usually prepared by the repair company and not by the engineer.
Typically the owner wants the engineering certification to provide to a buyer.
Buyers should be suspicious of such certifications for several reasons. Here are the questions I recommend you ask:
Was the engineer present when the work was done?
If so, how much time did he spend there? If the engineer or his representative was not at the site there through the entire process, the certification is of limited value. There is a saying in construction that you only get what you, or your representative, inspect.
Was a soil report ordered?
This is key. If the native surficial soil is stable, then money spent on foundation repair is likely to be a waste. If the piers/piles are not deep enough to reach stable soil, the repair may not be adequate.
Did the engineer or his representative make a written record of the depth of each pier or pile?
The effectiveness of slab foundation repair is closely related to the depth of the piers/piles. If the sealed repair plan fails to specify the depth reached for each pier/pile, then there is no independent verification that the work was done in accordance with the plan.
Who paid for the certification?
The normal situation is that the repair contractor refers to an engineer with whom he has a business relationship. Unless the owner retained an independent knowledgeable engineer of the owner’s choice, the certification is not worth much in my opinion.
What does the certification actually say?
What you want is a certification by a Texas Professional Engineer that states that the work was done in compliance with the repair plan prepared by the engineer. I have seen many certifications that merely state that the repair plan and work were typical for the Houston area. Typical for the Houston area is a pretty low bar, in my opinion.
Is the repair plan professionally done?
Most will be unreadable. A rough hand sketch with no dimensions, no scale, no target depth, no reference to a soil report, or no engineers seal is not a professional repair plan.