Reclaimed slate is natural slate that has already been on a roof, lifted carefully, sorted and sold on. On the right job it is the best product available: it already carries the colour and weathering that new slate takes years to acquire, and it keeps old materials out of landfill. On the wrong job it is a gamble. Quality varies from one stack to the next, the quantity on offer is never quite the quantity you can use, and the seller may know less about where the slate came from than the price suggests. So the sensible question is not whether reclaimed slate is good or bad. It is whether this batch, from this source, suits this roof. Before salvaged slate goes onto a roof we run a set of checks on it, and you can ask exactly the same questions of anyone who offers it to you, ourselves included.
When reclaimed slate is the right choice
Salvaged slate earns its place in a handful of situations, and it helps to be clear about which one you are in.
Repairs to a weathered roof
A new slate set among old ones looks like a patch for years, because fresh slate is darker and flatter in tone than one that has taken many winters of rain. Salvaged slate of a similar origin blends in almost at once. For a part-repair on a roof you are keeping, that matters more than the saving.
Listed and conservation roofs
Conservation officers tend to look kindly on salvaged material for matching, because it keeps the character of the roof intact. Our guide to listed slate roofs explains what officers expect on protected buildings. Whether reclaimed slate is accepted for a whole slope on a protected building is a conversation to have with B&NES, not an assumption.
Roofs where only part is being re-slated
If a rear slope is being stripped and the front is staying, salvaged slate from the stripped slope can be used on the front repairs, and the two stay in harmony.
When it is the wrong choice
Reclaimed slate is rarely sensible for a roof you want to leave alone for as long as possible. Part of the life of every slate has already been used. If the plan is a full re-roof on a plain modern house with no heritage constraints, new slate from a reliable source gives you a known quantity and a known thickness. And if the seller cannot show you what the slate is, where it came from or how much there really is, the bargain price is not a bargain.
How to judge the quality of a batch
You can learn a great deal about salvaged slate in a few minutes if you look at the right things. The checks below are the ones we use on a stack.
- The sound of it. Hold a slate by one edge and tap it with a knuckle or a hammer handle. A sound slate rings clearly. A dull thud suggests a hairline crack or laminating layers that are starting to separate.
- The edges and the tail. Look for flaking, where thin layers peel away. Slate that is delaminating at the tail will continue to do so once it is back on a roof. Our page on delaminating slate explains why.
- The nail holes. Old holes that are torn out, enlarged or too close to the head weaken a slate. A reusable slate has a clean hole well inside the edge, which can be re-punched higher up if necessary.
- The surface. Rusty streaks or small metallic spots can mean iron inclusions. They may bleed rust staining onto the slates below. We cover this in more detail under rust stains on slate.
- Thickness and flatness. Lay a few from different parts of the stack on a flat surface. Wide variation in thickness means a roof that sits unevenly and lets wind-blown rain in at the lap.
Colour deserves a fair look in daylight, with the slates wet as well as dry. A batch from three buildings can contain three tones. That is acceptable if the plan is to mix them thoroughly across the roof, and a problem if one tone ends up in a single patch.
Size matters as much as condition. Old slates come in many sizes, and a stack that appears to be one size often turns out to contain several. Measure a sample of length and width before you agree a quantity.
Working out how much you actually need
The number a seller quotes is almost never the number you can lay. Salvaged slate has losses at every stage, and the plan has to allow for them.
Start with the roof. The area of each slope, together with the slate size and the lap, determines how many slates cover each square metre. The lap is the overlap of one course over the one two below it, and it depends on the pitch and exposure. Our page on slates per square metre works through the arithmetic for the common sizes. For natural slate, one slate manufacturer's guidance puts the minimum pitch at 20 degrees for a 500 mm slate on a 115 mm lap in moderate exposure, and the lap has to deepen as the pitch falls, so the count changes with the roof, not only the slate.
Then allow for loss. Some slates will break when they are taken off the old roof, a few more will fail the ring test on sorting, and some will be cut or broken during the lay. The loss rate depends on the source and the care taken, so we do not give a figure. What we do is buy or reserve with a clear margin, because running out part-way through is the worst outcome. A matching slate found late may come from a different batch and a different tone.
Also allow for the parts of the roof that take smaller slates. On a roof laid in diminishing courses, the slates change size from eaves to ridge, so a single count of the total will not do. You need the right quantity of each size.
If your own roof is being stripped, the slate that comes off it is the first source. We sort it on the day, keep what passes and tell you how much of the new area it covers, then top up from reclaimed stock if that is needed.
The supply chain: where the slate has been
The seller matters as much as the slate. Reclaimed slate has no standard grade, no consistent label and no single marketplace, so the chain from the old roof to your scaffold deserves a few questions.
Where did it come from?
A reputable salvage yard can usually tell you the building, the region or at least the quarry type. Welsh slate, for instance, has a distinct character compared with imported Spanish slate. If the seller says it is Welsh, ask what makes them think so. A vague answer is a warning.
Who lifted it and how?
Slate taken off by a careful slater, one slate at a time, arrives in far better condition than slate stripped quickly and thrown into a skip. Ask if it was sorted at source, or only loaded.
How has it been stored?
A stack left on edge in the open for a winter takes up water and can show new frost damage. Slate stacked flat under cover is a safer buy. Ask to see the stack, not a photograph.
What exactly is the material?
Not everything that looks like slate is slate. Older artificial slates, including fibre-cement ones, can be mixed in with natural slate in a salvage yard, and the two behave very differently on a roof. Our guide to fibre-cement and man-made slates describes how they differ. If the seller cannot tell the two apart, buy elsewhere. Trust casework on one Grade I house in the city involved removing asbestos slates, and that is a reminder to establish exactly what a batch is before it goes on your roof or near your family.
Finally, get the terms in writing: the quantity by size, the condition, what happens to slates that fail inspection on delivery, and whether the seller will take back an unopened surplus.
What it costs, and what the saving really is
It is easy to assume reclaimed slate is the cheap option, and sometimes it is. But the saving is narrower than the price per slate suggests.
MyBuilder's slate roof cost guide (2026) reports typical UK installed rates of £100 to £180 per m² for natural slate, with Welsh slate at £140 to £180 and Spanish at £100 to £130. The guides do not publish a separate rate for reclaimed slate, so we will not invent one. Your fixed quote follows the survey.
What we can say is where the costs move. Reclaimed slate usually costs less to buy per slate than new Welsh slate of the same standing, but you pay for it in other ways. Sorting takes time on the roof. Laying slate that is slightly uneven goes more slowly. A larger margin must be bought to cover losses. And where the stock runs short, a top-up from a different source adds a second price. On a straightforward roof, a careful reclaimed job and a new Spanish slate job can end up closer in cost than the stack price suggests.
Where the saving is real is on heritage jobs, where the alternative to reclaimed slate is a more expensive new Welsh slate that still does not blend. Then the salvaged option can be both cheaper and a better match.
One more cost is time. A good batch of the right size may have to be found, which adds days or weeks before the roof can start. A leaking roof is covered temporarily while the right slate is found, so nothing is rushed.
Reclaimed slate also changes how a quote reads. Ask any roofer to state the quantity, the sizes, the source and the allowance for losses, so that you can compare two quotes like for like. For wider price context see our page on slate storm damage and insurance, which covers what an insurer may or may not pay to restore.
Fixing reclaimed slate so it lasts
Salvaged slate can only perform as well as the way it is fixed. The roof around it needs to be sound or the effort of sourcing good slate is wasted.
Battens should be new or demonstrably sound, set at the correct gauge for the slate size and lap. Old slates need fresh fixings: an old nail hole that has rusted out cannot be trusted, so each slate is either re-holed higher up or fixed with a hook, depending on the roof. Where a slate has lost length from a broken tail, it can be trimmed, but the lap must still be right.
The underlay is worth renewing while the roof is open. Salvaged slate does not make a perished felt any better. And the details around the slate, such as the lead in valleys and at chimneys, deserve the same attention as they do on a new roof.
Nail choice is where many reclaimed jobs go wrong. A new slate nailed with a poor-quality nail is no better than the old one that failed. Using nails that will outlast the slate keeps the repair from coming back. We look at that in our guide to nail sickness.
The last step is the survey. Before any salvaged slate is bought, we go up, look at your own roof, photograph it, and set out in the written fixed price how much of the slate is being reused, how much is sourced and from where. Our guarantee, ten years and in writing, covers how the slate is laid, not the age of the slate itself. If you hold an offer of a batch, send us the details and we will say whether it suits your roof. The wider work is described on our slate roofing page.