Consider the following reasons slab foundation repair aka underpinning should be rare or at least not common:
Underpinning a slab foundation in an expansive soil area is considered to fall within the jurisdiction of the Engineering Practice Act:
What this means is that foundation repair companies should follow a repair plan created by a Texas Professional Engineer. But it means a lot more than that. The Texas Section of the American Society of Civil Engineers has published a document titled: Guide For The Evaluation & Repair Of Residential Foundations, version 2. The Texas Board Of Professional Engineers has stated: if a complaint is lodged against a Professional Engineer who made a report concerning foundation performance, the TBPE may use a document titled: Guide For The Evaluation & Repair Of Residential Foundations, version 2 to determine if the engineer was in compliance with the rules of the TBPE. The following come from that document or from a Policy Advisory issued by the TBPE.
Any repairs or remediation must be cost-effective
In this context, the term cost-effective means: producing good results without costing a lot of money. More bang for the buck as compared to alternatives.
On this basis alone, foundation repair should be much rarer than is the case. The typical homeowner who is concerned about the performance of their foundation is concerned about door issues, drywall cracks and cracks in brick veneer. For most homeowners, foundation repair cannot compete with remediation and proper foundation maintenance in terms of cost effectiveness.
Recommended repairs should be practical and commensurate with the nature and cause of inadequacy and the seriousness of its consequences.
Recommending underpinning when the distress is cosmetic only is not, in my opinion, commensurate with the nature and cause of inadequacy and the seriousness of its consequences.
The engineer should provide options
The keyword is “options”, not “option”. Assuming no structural safety issues, underpinning may be an option, but it is hardly a requirement. More practical options include improving drainage, installing root barriers between deciduous trees and the foundation, installing an automatic foundation watering system, adding movement joints in brick veneer panels, making cosmetic repairs only, and the most popular option: living with the distress.
Foundation repair does not have to be recommended unless there is a structural safety issue or a structural integrity issue that cannot be repaired without underpinning the foundation.
The engineer should be fair to all parties
If an investigating engineer recommends underpinning he or she should have a good reason for doing so. If the report is for a real estate transaction, engineers have an obligation to be fair to all parties, not just the party who retained the engineer.
If a client has unrealistic expectations, the engineer should address that upfront
Foundation repair contractor advertisements have persuaded many people that, if there are signs or indicators of foundation movement, the foundation should be underpinned. That attitude is nonsense. Not every house needs to be underpinned and not every house benefits from underpinning.
Consider this quote from an Army Corps of Engineers technical manual titled Foundations In Expansive Soils:
Most slab foundations that experience some distress are not damaged sufficiently to warrant repairs. Damage is often localized by settlement or heave of one side of the slab. The cause of the soil movement, whether settlement or heave, should first be determined and then corrected.
Consider also this quote from the same manual:
The structure is seldom rebuilt to its original condition, and in some instances, remedial measures have not been successful.
The expectation that the house will be made whole again once the foundation has been repaired is unrealistic. Houses with cosmetic distress and /or other distress and even damage due to foundation distortion may not be good candidates for repair.
Houses constructed before 1980 may not make good candidates for underpinning.
These slab foundations usually have continuous perimeter grade beams but do not have continuous stiffening beams.