Slate (eternit) roofing

[jonw]

My builder is doing a loft conversion for me and the whole roof structure was replaced (necessary according to my surveyor). He has re-used the eternit slates from the roof (only 10years old).

On inspection I have notice he is using galvanised clouts rather than copper nails for fixing the top of the slates. He is using the correct copper disc rivet in the ususl place. Is it acceptable to use clouts instead of copper nails?

Secondly, viewing from the ground the lines of slates are not straight. They waver in an "s" shape, I estimate by 40-50mm and they don't all appear to sit down flat. Probably doesn't sound much but it is obvious from the ground.

Clearly roofing is not his forte.

How does a roofer normally ensure the lines a straight when viewed from the ground? Also is it possible that these slates are warped from being on the warped roof previously? Should I have insisted on new eternit slates?
Is this something that he can straighten or will he have to refit the slates?

 

[chappers]

building regs say you can use galvenisied nails but cooper or aluminium are better if ever you need to rip out the nails for a repair, it is always quite difficult to get re-used slates of any sort to sit as flat as they were originally but there should be no excuse for not getting the courses straight, its a simple matter of setting out your battens straight and evenly spaced ( I always check mine at every rafter before nailing in case the battens are bent) and then lining them up correctly as you work across the course.
Not really something that can be sorted in situ without removing the slates.

 

[jonw]

thanks chappers, appreciate the reply