Legal Question in Real Estate Law in Illinois

No. An incorrect appraisal is not a legally recognized reason to sue. Keep in mind that appraisal values is the appraiser's estimate of what the house is worth at the time and place the house was appraised, and may be different an hour after it's made.

Only if the original appraisers did something negligent. Also, you should look at your contract wiht the appraiser to determine if there is an exculpatory clause.

If everyone who disagreed with an appraiser's opinion on the value of a property could get the difference from the appraiser, there would not be any appraisers left. Some people get mad when appraisals are too high, and some get mad when they are too low. The only chance you have of a successful lawsuit is if the appraiser was negligent in some way, for example, if the appraiser calculated your house had 5,000 square feet but it only had 2,000 square feet.