Stone slate lasts a very long time. With upkeep, says the council's guidance, a Cotswold roof can comfortably pass a century and might run to two or three, and one cleared of growth every year could last twice as long again. Whether yours should be patched or taken apart depends on where the weakness sits.
Q2.1When is a local repair enough?
A few slipped slates, a lifted ridge stone or a cracked valley can be put right without disturbing everything around them. We work from a ladder or crawling boards so the load is spread, and we do not walk on slates that are loose. Each refixed slate returns to its own course with its original overlap, so the slope keeps the same pattern of lap and lie, and rain still runs off it as the original builders intended.
Q2.2When should a whole slope be re-laid?
Once battens have softened and pegs are failing across a slope, patching buys only a little time. The better route is to lift the covering, grade the stones, put in new battens and underlay, and then re-hang the same stones, topping up any shortfall with matching slates. That document reproduces an English Heritage policy favouring newly cut slates over second-hand ones. Salvaged slates, it says, belong on the building or group they were lifted from, since taking them from elsewhere strips somebody else's roof. Before a slope comes up we photograph it course by course, so the pattern of sizes can be matched when the stones go back, and the stones are stacked by size as they come off.
Q2.3Why are substitutes a poor bargain for real stone?
The same policy calls fibre resin, concrete and reconstituted stone slates inappropriate for historic buildings. On a modern unlisted house they may suit a budget, but they weigh differently, weather differently and look different from limestone. We set out what each option does and let the written quote carry the figures, so the decision stays with you.
