The industry-accepted commercial property inspection standards of practice is the International Standards of Practice for Inspecting Commercial Properties (ComSOP).
Provide a PDF copy of the ComSOP to your inspectors, clients, and consultants. You may choose to distribute it to consultants if their duties are found within it, and to clients for the list of the limitations, exceptions, and exclusions that are particular to their inspection project.
Included at the end of the ComSOP are various inspection agreements and checklists. You can also make copies of these documents and use them in the ordinary course of business. All of the agreements contain key elements to protect you, such as making a reference to the Standard. Contract law varies from state to state, so check for any local requirements before using them.