Reclaimed slate
Is reclaimed slate a good idea?
The short answer
Often yes, for repairs and for period roofs where the look matters. Reclaimed slate matches an old roof's colour and wear from day one, and a sound slate has years left in it. The risks are weak, delaminating or mismatched slates in a poor batch, so each one needs to be sorted and tested, and the supplier should say where they came from.
When reclaimed slate makes sense, how a batch is checked by hand, and the cost and matching questions to settle before anyone orders.
Used once, but not used up
Natural slate is a stone, and a sound slate has no clock ticking inside it the way a felt or a membrane does. CORC says slate that is kept in order can run past 100 years. A slate taken from a demolished roof after eighty years may therefore have decades left, provided it is still sound. What wears out first is usually the fixing, not the stone: the nails rust, the holes elongate, and the slate comes loose long before it fails.
That is the argument for reclaimed slate. It is already weathered to the grey-green of an old roof, so it blends into a patched slope instead of glaring like new stone. It is available in the sizes that older roofs used, and it keeps a heritage roof looking right from the road. The argument against it is that nobody has tested the batch for you, so the testing is your job, or your roofer's.
Sorting a batch slate by slate
A reclaimed slate is judged by hand. Hold it up by one corner and tap it with a knuckle or a nail: a clear ring means the slate is dense and sound, while a dull, flat sound suggests hidden cracks or layers starting to part. Look along the edges for flaking, and check both faces for pits or powdery patches. Count the nail holes. A slate with two holes near the head is fine; one drilled or punched too many times is a weakness.
Slates that fail go in the reject pile, and a sizeable reject pile is normal. A good merchant grades before selling, but a good roofer checks again on the roof. We sort into three groups: slates for the visible face, slates for hidden positions such as under the ridge, and slates to discard. Our page on re-slating a roof describes how a whole slope is laid back with sorted slates.
Sizes, thickness and the gauge that results
Older slate was cut by hand in many sizes, so a bundle of reclaimed slates is rarely uniform. On a roof laid in diminishing courses, with larger slates at the eaves and smaller at the ridge, that variety is the whole design. Mixed sizes in a modern roof are harder to lay, because the gauge, the distance between courses, depends on the length of the slate and the headlap.
Thickness is the other quiet variable. A thick slate sits proud of a thin one and leaves a gap that wind can enter or a step that holds water. Matching is easier when you have a few slates from the same roof, and we ask to see the existing ones before ordering. BSI itself cautions that BS 5534 may not fit the re-slating of certain old roofs laid in traditional or salvaged stone, so the decision rests on the actual roof and its slates, never on a one-size table. A reclaimed batch earns its place by how it behaves in your hand, not by its date.
Where reclaimed slate belongs, and where new is better
Reclaimed slate belongs on repairs to old roofs and on conservation work, and it belongs most where the existing slates are still handsome and sound. Arun's appraisal would like slate or plain clay returned to The Steyne's terraces where unsuitable modern coverings crept in, and calls for original roofing on Aldwick Road too. Salvaged slate suits both aims. Our page on a slate roof in a conservation area covers the consent side. On a listed house, work that alters the roof's special character needs listed building consent, so ask the council first.
New slate is the better choice for a complete roof where uniform quality matters, where the reclaimed stock is small, or where a guarantee on the material is wanted. Our comparison of natural against artificial slate covers the other alternative. Neither route is wrong: the roof's age, its location and your budget settle it, and the survey tells you which applies.
Cost, supply and what to ask a merchant
Reclaimed slate is priced batch by batch, according to size, grade and rarity, so a figure only means something for the stock in front of you. As a yardstick for new material, Checkatrade's slate table, dated September 2026, shows slate roofing at £160 to £210 per square metre and Spanish slate at £95 to £125. Read those as national yardsticks and never as our prices. A salvaged batch can come out cheaper or dearer than either, depending on how much of it survives sorting.
Ask the merchant where the slates came from, how they were graded, whether they are sold by count or by weight, and whether any rejects can be returned. Ask us to see a sample before the main delivery. You get the quote in writing once the survey is done. Where salvaged stock is part of the job, it is named there, because a roof made from mixed sources should never come as a surprise to the person paying for it. Our slate roofing page has more on the work.
Related questions
Reclaimed slate questions
Can I reuse the slates already on my roof?
Often, yes. When a roof is stripped for new battens or underlay, sound slates are sorted and laid back, with new slates blended in for those that fail. The ring and edge test shows which are worth keeping.
Do reclaimed slates look different from new ones?
Usually. They carry weathering, lichen stains and a muted tone that new slate takes years to acquire. That is often the reason owners choose them for a patch repair on an older roof.