Where does Horsham stone come from today?

On a tiled roof, a missing tile can be ordered from a merchant and delivered within days. A missing stone slab is another matter altogether. The slabs are natural sandstone, split by hand, and every roof is built from a range of sizes graded from big pieces at the eaves down to small ones near the ridge. A replacement has to match its neighbours in thickness, colour and size, or the repair shows from the lane and may not shed water properly.

That makes the stone, rather than the labour, the hardest part to plan, and the part that most often sets the date. When we survey a roof we count what is sound, what is spare and what is short, so that the quote reflects the real position rather than a guess. A roof with plenty of good stone in hand is not the same job as one that has lost a good share of its slabs to frost and breakage over the years.

Slabs lifted from other roofs are the first call, and a good roofer builds up contacts for them over time. They come from barns and houses being converted, from roofs where a slope has been re-laid and surplus remains, and from buildings that are coming down. Reclaimed slabs have one great advantage: they already look right. The weathering, the lichen and the colour took decades to form and cannot be copied.

The drawbacks are real. Each slab has to be checked for cracks and frost damage, since a slab that looks sound can part along its bedding planes once it is wet. A load is seldom one size, so it must be sorted and graded before it is any use. Our page on reclaimed Horsham stone covers what to look for, and why salvage is not always the thriftier choice once the sorting is counted.

When reclaimed stone cannot cover a shortfall, the alternative is new sandstone, quarried and split to size. Some comes from sandstone beds in the same region, picked for colour and grain. Being freshly cut, it looks paler and cleaner than the old roof, and the difference shows for some years. It is often used on the least visible slope, or at the ridge end, so the main faces keep their weathered look from the road. Over several winters, rain and lichen close the gap between old and new, though it never vanishes entirely.

It is also worth asking whether the stone suits the rest of the roof. Not every sandstone behaves like Wealden stone, and a softer or more porous one can flake sooner. The quote names what is proposed and where it comes from. Our guide to alternatives to Horsham stone weighs up the other materials that people consider, and what each gives up.

Because the stone has to be found, the working period can depend on it. A roof needing a hundred matched slabs can take longer to put right than one needing ten, and weather can hold up a delivery or a collection. At the survey we tell you which parts of the job hang on stone arriving and which do not, so the order of work is planned instead of improvised. If a slope has to be left covered by temporary protection while stone is found, we explain that too.

Price follows the same logic. The cost of stone, the time to sort and grade it, and any extra days of scaffold all feed one total figure in the quote. What you also get is a clear account of how much stone is reused, how much is bought in and why, so that nothing about the stone comes as a surprise once work has started. Our guide on why Horsham stone roofs cost more sets out the wider picture, and the price is confirmed in writing after the survey.

The most sensible stone is the stone you already own. Slabs stripped from a slope can be sorted, with the sound ones laid back and the weaker ones kept for the least exposed courses. Sometimes an outbuilding or an old part of the same roof can spare slabs, and a careful roofer asks about those before buying anything. On a re-lay the aim is to put back as much of the original covering as can safely be used.

If the building is listed, or lies within a conservation area, the choice of stone may be a matter for consent, and the conservation officer will often want to know where replacements have come from. Read our answer on like-for-like consent before agreeing to any change of material, and for the full range of stone work see the Horsham stone roofing page.