The manufacturer states 25-30 years for shingles, but it's rarely the case they actually last that long unless you're paying for premium shingles. I'm in Canada though, so perhaps the harsher weather has something to do with that. Regardless, in Canada at least, 25-30 years for shingles is not common; 15-20 is more realistic from what I can tell in my area.
GAF has a 50 year warranty on its shingles. People who are talking about failures after 10-20 years are buying cut rate product and having it installed shabbily.
Why do they degrade so quickly? I also live in UK and replacing an entire roof is not a common thing to do, every 50 years sounds about right, my roof is 35 years old without any leaks.
UK roofs typically aren't asphalt shingles like most homes in the US and Canada. Asphalt shingles are closer to sand paper than the tiles you're accustom too.
We had to replace ours after only 15 years (and we should have done so earlier). The manufacturer's claims are suspect. Expansion/contraction due to the hot/cold cycle caused ours to crack (literally apart in some cases).
