Contractor Malpractice
Q. When I brought a contractor to look at dampness in my basement, he told me he was pretty sure there was seepage and excavation would be needed to fix the problem. After thousands of dollars of work, the dampness was no better! In the end the problem turned out to be condensation, which required a very inexpensive solution. Do I have to pay the contractor for the unnecessary work?
A. The problem of bad advice is hardly a new one. The young advisors who suggested to Rechovam to rule with harsh discipline were probably well meaning, but the King would have been better off following the advice of the elders who advised him to be a servant of the people. (I Kings 12.)
Jewish law makes an interesting distinction regarding liability for bad advice. If the person giving advice is an amateur, yet gives an opinion knowing it will be relied on, then he is liable for any losses he causes. But an expert is exempt. The reason is that an amateur has no business giving advice; if he gives it, he'd better take full responsibility. But an expert is giving valuable professional advice; even if he happens to be wrong, we assume that he gave the best possible suggestion.
Another distinction: Even an expert is liable if he receives payment for his advice. One of the things that the client pays for is for the expert to stand behind his judgment.
How does this apply to your situation? One way of looking at it is that the contractor wears two hats. In his "advisor" hat he diagnosed the problem, giving a free estimate; an expert advisor who works free is not liable. Afterwards, in his "workman" hat he carried out your own directions. Thus he deserves full payment.
According to this understanding, the contractor would still be liable if he is not really sufficiently knowledgeable and experienced to make a proper diagnosis of basement dampness.
Another point of view is that the estimate is not really free; it's just included in the price of work. Then the contractor could be responsible for his misdiagnosis, unless he clearly explained that he was not completely sure and the work is on your responsibility.
Bottom line: if the contractor is really experienced and qualified, and you knew you were getting only his best efforts, then your case is just one of bad luck. If you suspect that a more experienced contractor would have saved you the headache and expense, then you are within your rights to negotiate some kind of compromise, or to demand arbitration.
SOURCES: Shulchan Aruch, Choshen Mishpat 306:6