Professionals who are concerned about their legal liability resulting from negligence or errors or omissions in their professional service should purchase Professional Liability coverage.
A Contractor designs additions and then builds them for homeowners.
After completion of a structure a wall collapses causing damage and injury. The collapsed wall was due to a flaw in the design of the structure, thus the claim was denied by the contractors general lability.
Professional liability for the design work would cover this claim.