Slate fixing failures can appear one at a time
Older slate can remain usable after the original nails have corroded. Repeated slips across the same row suggest the fixings need more attention.
Shared-looking drainage needs careful tracing
A blockage near one outlet can cause water to overflow further along the row.
Chimney details can affect the adjoining roof area
Soakers and rear gutters sit close to party lines, and water can travel before appearing in one house.