How often should a metal carport be cleaned, and which cleaners are safe to use?

Rinse as needed to remove dust and salts; plan a gentle soap-and-water wash every season or after storms. Use mild detergent, a soft cloth or brush, and lots of fresh water; avoid abrasives, solvents, and harsh chemicals that can damage coil-coated finishes. Clean on a cool/overcast day and rinse thoroughly.