Can old slates be reused on a re-slate?

The reason a slate roof fails is usually its fixings, as our answer on nail fatigue explains. The slate itself is dense rock that does not rot or rust. Sources such as MyBuilder (2026) quote natural slate lasting 80 to 100 years or more, which is a good deal longer than iron nails or softened battens.

So when a slope is stripped, the question is not whether slate can last, but which individual slates still can. Reuse keeps the roof looking the same, preserves the colour and weathering you already have, and avoids paying for stone that does not need replacing. It also means fewer lorry loads of new slate on narrow lanes and fewer old slates to dispose of, which suits many of the steep, tight streets around Stroud. It is also the like-for-like route on older properties, where a new slate of a different size or tone stands out. Hand-split old slates in random widths, found on many Victorian terraces and cottages, are especially worth keeping, because modern machine-cut slate has a more uniform look.

Stripping is done by hand, beginning at the ridge end of the slope. Each slate is lifted clear, usually by cutting or pulling the old nail, and stacked by size. Rough handling cracks slate, so this is slow, careful work, and it is one reason the labour on a reuse job is not small. Stacks are kept off the ground and covered, since slates left leaning will bow or chip, and the roof is covered with sheeting each evening so the building stays dry while the slope is open.

Sorting follows, and it is where a roofer's eye matters. Each slate is checked for the following:

• A clear ring when tapped, which suggests it is sound and a dull sound which suggests a hairline crack
• Delamination, where layers are flaking at the edges or face
• Broken corners and old nail holes torn through the edge
• Enough length left to give the headlap the roof needs

Sound slates go into piles by length for relaying, and the rest are thrown out. Grading matters because slates are laid in courses of similar size, with the longer ones low on the slope and the shorter ones towards the top. We tell you how the sorted pile looks before relaying begins, and it forms part of the quote's logic since a re-slate with few survivors costs more in new slate.

An old slate already has nail holes, and they are in the wrong place once the head of the slate has rusted or torn. To reuse it, the slater punches or drills new holes, often a little lower or after trimming the damaged head. That shortens the slate slightly.

Length is not a trivial detail. The overlap of one course on the next, the headlap, depends on slate length and the roof's pitch, and a shorter slate gives less overlap. For a 500 mm slate laid with a 115 mm headlap in moderate exposure, BS 5534 indicates a minimum pitch of 20 degrees for natural slate. Reused slates re-holed short may need a larger lap than the original, which is why we check the headlap before a single slate goes back, and why a shallow roof may need new, longer slate in places. See the minimum pitch for slate for the figures.

No old roof gives every slate back, and nobody can say in advance how many will pass. Cracked and delaminated ones need replacing, and the gap is filled in one of two ways. Reclaimed slate, taken from another roof, matches the weathered look and thickness. New slate is consistent but starts fresh in tone and has to be chosen carefully to match the size and the stone.

On a house in a conservation area or a listed building the choice may need agreement with the council, which is covered in slate roofs on listed and conservation buildings. For a plain house, it is more about appearance and budget. Reclaimed slate is not necessarily cheaper than new, since sound slate in matching sizes is sought after, and its quality varies, so we inspect it before it goes on your roof.

The saving depends on how many slates survive the sort. A re-slate in new Welsh slate is £140 to £180 per m² and Spanish £100 to £130, according to MyBuilder's 2026 guide, so every slate that goes back on reduces the material bill. A short sorted pile also tells us early if a full re-slate with mostly new slate is the realistic route. Labour, new battens, underlay, scaffold and waste still apply, and the sorting adds time.

Reuse is not free of risk, either, and the risk is mostly cracks you cannot see. If a hairline crack hides in a slate, it can leak later, so poor slates are rejected, not squeezed back in. Your quote covers the reused slate and the new slate, we put a 10-year guarantee on our workmanship in writing, and clear the site when we finish. Keep the paperwork, because insurers may ask later what a repair involved: the insurance answer has more. Start with our slate roofing page, or call 01453 933613.