Caveat emptor, and due diligence. Although I am not a licensed professional anything, I use the phrase "contingent upon favorable inspection by home inspector or other licensed trade professional(s)". I've got enough friends that are licensed professional somethings that anything I find can usually be backed up in writing by someone. We've done a dozen or so real estate deals over the years, both commercial and residential, and that phrase has never failed. It applies to electricians, plumbers, structural engineers, roofers, etc, and it will hold water in most courts. Be as broad and encompassing as the seller will stand for in the purchase agreement. You can put anything that is legal and agreeable to both parties in a PA.
It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.