Almost none. That's one of the reasons our buildings come with them standard. Check it once a year for any debris, fallen branches, or leaves that might be sitting in a valley. Clear heavy snow if it accumulates several feet deep, though the roof pitch handles normal Michigan winters on its own.
Metal doesn't rot, doesn't grow moss, and doesn't need replacing every 20 years like asphalt shingles. It's about as close to maintenance-free roofing as you can get on a building this size.



