Phil B. forgetting the technical specifics of the case and focusing on your general question, "How does ‘technically infeasible’ work from a liability standpoint?"
Let's assume:
- You have an existing facility that meets all portions of the building code under which it was originally permitted.
- You've proposed an addition, which is where the AHJ gets involved.
- There is some component or aspect of the related path of travel that doesn't meet the accessibility code or ADA for new construction
- Your AHJ has declared full compliance to be technically infeasible, due to structural reasons.
- The owner's legal counsel has also looked at their financial capabilities and determined that full compliance for this component is not "readily achievable" (note that this is a different standard than "technically infeasible").
OK, now let's assume an ADA serial litigant comes along and sees the non-compliance with the 2010 ADA Standards (whether or not there was a wheelchair tip or an ankle turn). He doesn't know that it's been vetted for technical infeasibility. In this incidence, he's going to file a suit, naming as many defendants as possible.
- Do you have a legitimate defense of "technically infeasible" and "not readily achievable"? Yes, of course.
- Will you prevail in court, especially having a record on file at the building department of having reviewed and documented the technical infeasibility? Yes, probably. In that case, you would not be found liable. Hopefully, this answers your original question.
- Will any of those records keep the litigant dragging you into a legal battle in the first place? No. Welcome to the American legal system.
Note that in California, we have the "CASp" program, where a certified access specialist can document (in advance to the incident) your good faith efforts at compliance, and it can provide you with a defense that can keep the case from ultimately going to court. However, that doesn't stop the initial complaint, and the related hassle that attends it.
But let's face it, the only way you can avoid the initial complaint is if it already looks code-compliant.