Eh? My crappy roof was installed in 1945 and has some life left.

What sort of roofing lasts 25 years?

Afaik shingle roofs (common in US) need replacing every 10-20 years.

I actually wonder how solar panels reduce the rate at which a roof deteriorates. The panels themselves should bear the brunt of the light and rain that the shingles below them would otherwise endure, but on the other hand the panels don't cover the entire roof, so maybe at best you'd need to replace less of the roof but on the same schedule.

Yeah, that makes sense to me. I don't know the specifics of shingle deterioration, but just having them physically shielded from light and precipitation has got to drastically improve their lifespan. That's a good point about only part of the roof being protected though.

The president of the roofer's lobby has entered the chat!

Composition roofs need to be replaced when they are worn out and not before that. Good materials competently installed could last 50 years, more in mild climates. If you have the kind of weather that will wear down a roof in 10 years you probably cannot have solar panels.

Asphalt singles

Is there a reason that corrugated iron, concrete tile or similar aren’t used? They last near indefinitely if looked after, and a hell of a long time if not looked after.

They are very cheap.

My parents neighborhood is coming up on 25 years old and they are having to replace the layers under the roof tiles. The tiles themselves will probably last a thousand years but the under layer has a lifetime. They pull off the tiles, replace the waterproof layer and put the tiles back on — apparently takes just a couple days and they get better nails so the tiles don’t fall off during the windy monsoons.