Simon wrote:
Hmm so it seems the concensus is that the fibre cement is the better
material, so I'll go with that approach. Is it actually "better" than
the old asbestos stuff

I doubt it's actually better. Could be, though - I'm not sure
how it is made.


or could my original one just have been badly
installed? I say that because the last roof is probably only 10-15
years old, way less than the 40 years lifetime suggested for fibre
cement.

It's possible. The 40 years I suggested was based on experience
of asbestos cement roofs that have not been mucked about with -
if the roof's been bumped, or structure isn't quite rigid, I bet
it could fall to bits early.