Here you can read about this.
http://varvilla.se/5-fragor-om-tak/
5. How long does a roof made of different materials like metal, tile, asphalt, etc. last?
Common roofs with underlay felt and roof tiles have a lifespan of 40-60 years, after which the felt, battens, counter battens, and tiles must be replaced. In cases where you have clay or concrete tiles, they can often be reused as their lifespan is longer. An asphalt roof has a lifespan of about 20-30 years, while a metal roof lasts approximately 30-40 years. (It's difficult to say exactly how long a specific roof type lasts, as it depends on the circumstances).
http://varvilla.se/5-fragor-om-tak/
5. How long does a roof made of different materials like metal, tile, asphalt, etc. last?
Common roofs with underlay felt and roof tiles have a lifespan of 40-60 years, after which the felt, battens, counter battens, and tiles must be replaced. In cases where you have clay or concrete tiles, they can often be reused as their lifespan is longer. An asphalt roof has a lifespan of about 20-30 years, while a metal roof lasts approximately 30-40 years. (It's difficult to say exactly how long a specific roof type lasts, as it depends on the circumstances).
For 40 years we've been told. The houses were built around 1970, and many still have the original galvanized metal roof, fastened with farm screws on the beams. The gaskets have obviously worn out long ago, and the weather has stretched the holes, so it's risky for many of them now. But they deny the problem with these words: "It was wrong from the start, it wasn't age-resistant plastic, so they redid the roofs in 1975, so the roof has already been replaced once."
Another one denies it by saying "Regular painting can extend the lifespan of a metal roof by 20 years." Yes, but his roof is still unpainted and it's been 50 years now.
We replaced ours two years ago, and the carpenters noted that it had started to leak a bit but hadn't yet caused any real damage, just a few boards under the felt needed to be replaced in a couple of places where the wind had probably managed to tear more.
Another one denies it by saying "Regular painting can extend the lifespan of a metal roof by 20 years." Yes, but his roof is still unpainted and it's been 50 years now.
We replaced ours two years ago, and the carpenters noted that it had started to leak a bit but hadn't yet caused any real damage, just a few boards under the felt needed to be replaced in a couple of places where the wind had probably managed to tear more.
Double-lock seam metal roofs or panel-covered roofs often last 70-80 years if they are maintained a little from time to time. Just look around at the houses and talk to people in the gardens if you live in a better and slightly older residential area. Many roofs from the 1950s are still good.