N_Cook wrote:
Or as tile and slate seems about the same weight per sq foot, what is
the amount of overlap for slates and for tiles?

Dunno. But around here there are hundreds of Victorian terraced houses.
Those with slate roofs are fine, those with concrete tile all have a
pronounced 'dip' in the ridge.

I believe its a good idea to reinforce the roof structure to avoid this.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk