Semi detached house, both properties sharing he same type of slate roof.
One house now has had their roof re-done. New battens, felt and the original slates replaced with tiles.
Now the problems is.. how should the two different roofing areas meet? From the ground view it appears that the original slates are at a lower level than the tiles, but instead of the tiles overlapping the slates, the opposite has taken place.
The slates have now been prised up to go over the tiles, so the run of slates as they approach the tiles gradually rise up like a ski slope to meet the thicker and higher tiles.
From the ground it is not possible to see what, if anything, has been used to seal the joining. The worry is that the slates have been disturbed, and the original nailing holding slates to old battens have been weakened.
Looking at other properties with similar different roofing material there seems to be a variety of joing styles... but none that looks like the roof we have.
What is best practise in a situation like this?