A very exposed coastal property was inspected by Colin Cockram last week that had a series of mono-pitched roofs. The roof slopes were measured and were found to have a pitch of around 16 degrees. The tiles were also checked and it is estimated that there was a 100mm headlap. The type of tile was seen to be a Marley Eternit single Roman pantile which are designed to go to pitch of no less than 25 degrees with a 100mm headlap. Therefore these roof pitches are far too shallow.
It is likely that the roofs will need to be stripped and recovered with a different type of material such as single membrane system. This will be very expensive easily justifying the cost of having a full Building Survey undertaken.