Reclaimed slate is slate that has already had one life on someone else's roof. It is lifted from a demolished building, a re-roofed barn or a house that has been stripped, graded by a salvage yard and sold on. Used well, it gives a new roof the weathered look of an old one and keeps good stone out of the skip. Used badly, it brings a roof full of tired slates that leak within a few winters. The material can be excellent or poor, and the person laying it makes the difference. This page sets out what reclaimed slate offers, where it goes wrong, how to judge a pile before it is bought, and when new slate is the better choice.
What reclaimed slate is, and where it comes from
There are three main sources. The first is salvage from demolition, where a roofer or a dealer takes the slates off a building that is coming down. The second is the strip of a roof that is being re-covered, where the contractor keeps the sound slates for sale or for a later job. The third is your own roof: the slates that come off in a re-slate and are sorted and put back. The last is the safest, because you know where they came from, how they were laid, and how they behaved.
Salvage dealers grade the stock by size and condition. Slates are sold in bundles or pallets of one length, or in mixed sizes, and a good yard will tell you the origin, the approximate age and the number of holes. Cheap lots from unknown sources are the ones to treat carefully. A slate that looks fine in a pile can still be near the end of its life.
The case for reclaimed slate
The first argument is looks. A freshly laid roof of new slate has a flat, blue-grey sameness for the first few years. Reclaimed slate comes already weathered, with the soft variations of colour that take decades to develop on a new roof. On a period house, a barn conversion or a cottage in a conservation area, that character is often exactly what the planners want to see. Our page on slate roofs on period and listed homes explains why like-for-like materials matter in those settings.
The second argument is matching. If a roof of old Welsh slate needs patching, new slates will stand out for years, while reclaimed slates of the same origin blend in quickly. For repairs and partial re-covering, sourcing a few hundred matching slates is often the only way to keep a roof visually even.
The third is durability. Slate that has stood for a century has proved itself. If the stone has lasted that long without delaminating, the odds are good that it will last another century, provided it is nailed on properly. Good salvaged slate can match the lifespan of new stone, and sometimes beats cheaper new imports.
The fourth is cost, though this is the argument that is most often overstated. Reclaimed slate can be cheaper than new natural slate, but the saving is partly eaten by sorting, extra labour and wastage, so the price of the stone alone is only part of the sum. Published guides give typical UK ranges of £120 to £180 per m² for natural slate re-covering, and a roof built from reclaimed stock may land somewhere inside or below that range, but your fixed quote follows the survey. Do not assume that cheaper slate means a cheaper roof.
The pitfalls
Most reclaimed slate problems come from five things.
Hidden delamination
A slate can look sound and still be made of layers about to part. The risk is highest with old slates that have spent years on a damp, shaded slope. Dealers do not always sort them well.
Old nail holes
Every slate arrives with holes from its first roof. On a new job, the old holes may sit in the wrong place for the new gauge, leaving the slate with weak or doubled holes and risking a split. A good slater re-holes where needed and avoids using a slate with holes too close to the edge.
Inconsistent sizes and thickness
Salvaged lots are rarely uniform. A pile may contain a spread of lengths and thicknesses, and thick slates laid beside thin ones lift the courses and let wind-driven rain in. Careful sorting into thickness groups is part of the work, and it takes time.
Not enough of them
Run out of reclaimed slate halfway up a slope and you may not be able to buy more of the same. Order a margin, typically more than a new job would need to allow for breakages, and keep spares for future repairs.
No guarantee on the material
A new product comes with a maker's guarantee. A reclaimed one does not. If a slate fails, the cost of replacing it is yours. The workmanship guarantee on the job still applies to the laying, but not to the age of the stone.
How to judge a pile of reclaimed slate
You can check slates yourself before you pay, and a decent dealer will expect it.
- Hold a slate by one edge and tap it with a knuckle or a small tool. A clear ring means a dense, sound slate. A dull thud suggests a hairline crack or loose layers.
- Look at the edges. Flaking, layered or powdery edges mean the slate is delaminating.
- Check the face for rust staining, white bloom or pitting, which are signs of mineral problems in the stone.
- Check the nail holes. Slates with elongated, torn or double holes are not worth using.
- Compare thickness across the pile. A mix of thin and thick slates will not lie flat.
- Ask where they came from. A roof that was well maintained is a better source than one that leaked for years.
If you are not sure, a roofer should do this for you. Rejecting bad slates costs far less than stripping a new roof two winters later.
Fixing, layout and how a reclaimed roof is laid
A reclaimed roof is laid on the same principles as a new one, with some adjustments. Battens are set to a gauge that suits the length of the shortest slates in the batch. Courses are laid diminishing, with the longest, thickest slates at the eaves and the shorter, thinner ones towards the ridge, which is how traditional roofs were often laid and which suits mixed-size stock. Each slate is fixed with two nails, in copper or stainless steel, not iron, because iron is what caused the original problems. Where the roof is exposed, hooks or clips at the tail give extra security; our page on slate hooks and nails covers that decision.
Mixing stock from different sources can look patchy. Where a mix is unavoidable, a good slater blends the batches across the roof so there is no obvious change of tone. Our guide to mixing old and new slates goes into the details. The underlay beneath should always be new, and so should the battens, because there is little to be gained from a costly slate on tired timber.
Questions to put to a dealer
A reputable salvage yard will answer these without fuss, and a vague reply tells you something too. Ask where the slates were taken from and roughly when the building went up. Ask whether they were stripped by hand or knocked off in a demolition, because slates dropped in a pile arrive with hairline cracks you cannot see. Ask what size and thickness range the lot covers, and how many square metres of roof it will cover once the shortest lengths are allowed for. Ask whether any have been wet-stored in a heap, since slates left stacked flat for years can stain and soften at the contact points. Ask about returns: a dealer who stands behind a pallet will usually take back slates that fail an agreed sample test.
Then ask your roofer to look before you commit. A pallet can be returned or rejected when it sits on a yard, and it cannot be un-laid once it is up the roof.
Weight, pitch and the approval rules
Old slate is generally thicker than modern imported slate, so a roof of reclaimed stone can weigh more than the new roof it replaces. Thicker slate also needs a slightly different batten spacing. If your old covering was concrete tile or a thin manufactured slate, a switch to heavy reclaimed stone can cross the line at which approval is needed: a covering 15% or more heavier than the one it replaces brings a building control application and possibly strengthening to the rafters. Because those checks fall on the roof as a whole, not on a single batch of slates, it pays to settle the weight question with your building control body at the start.
Pitch matters too. Slate sheds water well on a steep roof, and shallow pitches need bigger laps and a more careful underlay. Reclaimed slate, which is often irregular, can be less forgiving on a low pitch than a new regular slate. We would tell you if your roof is too shallow for the stock you have found.
When new slate is the better choice
Reclaimed stone is not always the right answer. Choose new natural slate when you cannot find enough matching stock, when the roof is large and uniform, when the budget needs predictable material costs, when a manufacturer's product guarantee matters to you, or when the roof structure is the real problem and the slates are only part of the work. New slate also suits a modern extension next to an old roof, where a deliberate contrast can look better than a poor match.
Your own slates are a different case. If your roof was sound until the nails went, then lifting the slates, sorting them and re-laying them with new fixings is often the cheapest and best route. It also leaves you with the right slate in the right size and colour. We describe that option in our guide to whether a slate roof is worth repairing.
Our approach
When you ask us about reclaimed slate, the survey comes first. We photograph your roof, tell you what is salvageable, and say whether a reclaimed batch is realistic for your house. If you have found slates yourself, we are happy to look at them and give an honest opinion before you buy. The quote sets out which slates are reused, which are bought in, and what happens to any that do not pass the sort. You get it in writing at a fixed price, the finished work is covered by our 10-year workmanship guarantee, and we leave the site clear. For the wider picture see slate roofing in Basingstoke, or message us on WhatsApp or ring 01256 213956.
