In the (not too distant) past,  the pointing was just a thin layer of oxide coloured sand/cement. The ‘cement’ pointing was put together relying on the skill of the roofer and the thin layer had a good chance of sticking onto the bedding without cracking.

With age and movement on the roof, the bedding (and attached pointing) would start to crack – and the ridge capping will then start to dislodge itself and sometimes slide off the roof. This is when the roof has to be “repointed” – to maintain the ridge security. Usually, only the very loose bedding is removed and fresh bedding installed locally to support the ridge capping. Then the rest of the existing (sometimes cracked) bedding is prepared to receive the new pointing.