Unstable stonework

[88v8]

The design I have is quite common and the boards are always exposed rather than leaded over. Unsurprisingly I have seen a fair number that are in poor condition.

Well, I'd lead it over.
It will be a jolly sight cheaper than having to revisit the job in a few years.

With the benefit of hindsight and experience, original design does not always equate to good design. And after all, for the original builders, leadfree was a lot cheaper ....

Your vanishing builders...yes, it's funny how builders so often have eyes bigger than tummy.

Ivor