Exerpt from “The Complete Home Inspection Book”
"You should use the term “qualified contractor” in your recommendation in order to protect yourself. If you don’t and a client hires someone who’s not qualified and they wind up battling each other in court, you may join one of them as a defendant.
“Qualified” is one of those terms that are hard to define. Contractors often make decisions that originally were made by an engineer. Contractors base these decisions on their years of experience and assume liability for the results. A contractor who usually makes good decisions is qualified. One who usually makes bad decisions is on his way into court and out of business. This is also true for Home Inspectors."