On 29/09/10 11:00, N_Cook wrote:
I hollared up to a roofer of 30 years scrabbling, reroofing in the same road
today. He did not know a specific ratio but reckoned a cement tile roof is 3
times as heavy, for the same roof-scape. His unseen mate on the rear roof
reckoned about the same


David Ireland's book 'How to rescue a House'
says concrete are 4 times heavier than slate

[g]