Glueing replacement slates

[mjburrows]

Roofer wants to glue in replacement slates. Not sure I like this idea because:
- it will make further repairs in the area difficult because there are now 3 slates glued together. A roofer working on second repair would not know this and would have difficulty determining which slates to remove.
- there is a small possibility of water getting trapped above glue and find a way into the roof space
- We don't know the lifetime of the glue, but I guess it is less than Hall Hooks or tingles
Any views?

 

[datarebal]

Hall hooks everyday.
Regardless of life span of glue, do you know how long it is before a layer of slate departs ..