Here is a problem we were not expecting to find when
we started to repair this roof that had a few slates that had slipped

The usual problem is that the nails holding the slates in place have
eroded and are no longer able to hold the slates in place

(When this happens, we call it a Nail Sick Roof)

 

In this particular case, the top row of slates BUTTED up to the Ridge Tile,
rather than continue to the top of the roof slope, under the Ridge Tile

The Ridge Tile was bedded in a huge amount of concrete in an attempt to waterproof this area

This concrete may have worked for a time but eventually water seeped under the Ridge Tiles, causing the lathe to rot

The new slates were fitted with the correct laps onto new tanalized lathe 

The new slates were fitted with the correct laps onto new tanalized lathe

The Ridge Tiles were then bedded in new mortar giving a neat weatherproof finish