"No one wants to shell out for a new roof when it’s not needed, the American Institute of Architects notes in continuing education advice for professionals published in Building Design + Construction. But then again, "No building owner wants to be caught unprepared by catastrophic roof failure"

So when is a bad roof bad enough?

"When leaks become recurrent and pervasive and the roof approaches the end of the warranty period, it’s probably time to consider roof replacement," write Deborah J. Costantini, AIA, and Michael S. Pereira, Assoc. AIA, of Hoffmann Architects, Inc. in New York, Connecticut and Virginia.

Technology changes over time, Costantini and Pereira note, and simply asking for a bid on a new roof is probably not the right first step.

"A better strategy is to get a detailed picture of existing conditions first, then use that information to select the right roofing system for the job," they say.