Each slate hangs from a pair of nails through its head, and the course above hides them completely. That neat arrangement is what keeps a slate roof watertight, and it is also why a repair is awkward: there is nothing to get hold of, and nothing to nail into without lifting the slates around it. Repair methods have grown up around that problem. A slater can slide a new slate into place and hold it with a tingle, a metal strip with a fold. Or they can use a clip or hook that grips the slate from below. Each has a place and a limit. This guide explains how a single slate comes out and goes back, what each fixing is, when each is the right choice, and when a pattern of repeated repairs is telling you something else about the roof. It sticks to the repair itself. Larger questions of cost and replacement are covered on other pages.
How a slate comes to be loose
Slates rarely fail because the stone breaks. They slip because the fixing under them has given up. A slate is hung on iron, copper or alloy nails, and the commonest older nail is iron, which corrodes where it passes through the stone. As the nail thins, it snaps or pulls through the hole, and the slate drops by a few centimetres until the course below stops it. From the pavement it shows as a slate sitting low, with a gap showing the batten above it. Repairers call this slipping, and the wider condition, where nails fail across a whole roof, is nail sickness, which we cover on a separate page.
The second cause is breakage. A slate may crack across its width from a branch, a ladder, a heavy foot or frost working at an old flaw. A cracked slate may stay in place for a time, but it lets water through along the crack and becomes a slipped slate in the end.
The third cause is the slate itself giving up. If the stone is delaminating, flaking in layers, or has softened along its tail, replacing the fixing will not help, and the slate has to be changed. A slate in this state often lets go at the tail and is held by its nail alone.
Knowing which of the three you have shapes the repair. A slipped slate on a sound roof is a quick fix. A cracked one is a replacement. And a group of slates failing for any reason, slipping in several places or flaking all across a slope, points to a cause that patching will not cure. If you are seeing a loose slate from the ground, our page on slipped slates covers what to check next.
Replacing a single slate, step by step
The method is simple in principle and fiddly in practice. We start by working out why the slate has failed, then choose a replacement that matches it in size, thickness and colour. A modern slate pushed into a weathered roof looks out of place, so where colour matters we use reclaimed slate. Our page on replacing a broken slate goes through the matching decisions.
Taking out the old slate
The damaged slate is held by nails hidden under the course above. To release it, the slater lifts the slates above just enough to reach the nails, then uses a slate ripper, a long flat tool with hooks at the end. The ripper is slid up under the slate, hooked around a nail and either pulled or struck to cut the nail through. Once both nails are cut, the slate slides out.
Preparing the gap
The gap is checked. The batten behind it should be sound, since there is little point in putting a new slate onto rotten timber. Any stubs of old nail are removed, and the underlay, if there is one, is looked at for tears, because water may already have been getting behind it.
Fitting the new slate
The replacement is slid up into the gap beneath the course above, until its head sits at the right height and its tail lines up with the courses on either side. Because the nail positions are covered, it cannot be fixed in the normal way. Instead it is held by a single fixing under its tail, which is where the choice of tingle, clip or hook comes in. The slate must sit flat, in line, and with the same overlap as its neighbours, or it will either rattle in wind or let water in.
A properly done repair leaves no visible mark beyond the slate itself, and often a slight difference in tone that fades over a few seasons.
Tingles: the traditional repair
A tingle is a narrow strip of metal, usually copper or lead, tacked to the batten and folded up over the tail of the replacement slate. The slate sits in the gap, the tingle is nailed through the batten under the course below, and the free end is bent up and around the slate's lower edge to hold it. It is the classic, long-established way to refix a single slate when you cannot get at the original nail holes.
Done well, a tingle is a good repair. Copper is durable and does not rust, and lead is soft and bends to the slate. When a tingle is set neatly, with a clean fold and a narrow visible width, it is hard to pick out from below, and on many old roofs it is the right solution because it is a traditional detail that matches the building. Our page on the slate tingle goes into more detail.
Tingles have limits. A tingle shows at close range, as a small bright or grey flag on the face of the slate, and a roof covered in them looks patched. Lead tingles can stretch over time if the slate is heavy or the pitch steep, letting the slate slide down. A tingle also relies on one fixing and the grip of a fold, so it is less secure than the original two nails. That is acceptable for the occasional slate. It is not a way to hold up a roof where many slates are loose.
The point is to treat the tingle as an individual repair, not as a system. If you count more than a few across a slope, the roof is telling you the original fixings are going, and the answer lies elsewhere. As a rough test, one tingle is a repair; a dozen is a diagnosis.
Clips and hooks
Modern repair fixings do the same job as a tingle with different hardware. The common ones are a stainless steel or copper clip and a hook.
Clips
A repair clip is a strip with a bent hook at one end and a flat tail at the other. The tail is nailed to the batten below, and the hook turns up to engage the bottom edge of the slate. Clips are quick, hold well, and are available in stainless steel and copper. They are the usual choice for patching a few slates on a sound roof when a tingle would look out of place. Some are designed to be nearly invisible, with a slim profile that lies behind the tail.
Hooks
A slate hook is a longer fixing, shaped like a J, that is driven into a batten and hooks over the tail of the slate. Hooks are normally part of a full roof design, where every slate is held by a hook through the batten instead of nails through the slate, and not just a repair method. A manufacturer's guidance sets a floor of 25 degrees for hook fixing, which rules them out on a shallow roof. Our page on slate hooks goes through where they fit.
Choosing between them
On a listed or traditional building, we lean towards copper tingles because they match the way the roof was originally maintained and are the least intrusive in appearance. On a more modern roof, or where a number of slates need re-fixing, a stainless steel clip may be a better engineering answer. The metal matters most: copper, stainless steel, or a good alloy, and never plain steel, which will rust and cause the same fault again. We name the fixing in the quote.
None of these is a patch for a roof with failing nails everywhere. They are tools for individual slates.
When repair stops being the right answer
Repair is our first choice where it works, and on a sound slate roof with a few slipped or broken slates it usually does. But there is a point where continued patching is poor value, and it is worth being clear about how to recognise it.
The signs are these. Slates are slipping in many places and on more than one slope. When we lift a slate, the nails come away crumbling with rust. The underlay, if present, is perished and torn. The battens are soft or split. Slates are flaking on the face. Or you have been repairing the same roof year after year, and each visit finds new problems. In those cases, the cheapest long-term answer is often a re-slate, using the sound slates from the old roof, and Re-slating a roof describes that work, and the choice between the two routes is weighed in repair or reslate.
It is also worth distinguishing repairs to slate from repairs to the details around it. A leak that appears below a chimney, a wall or a valley may not be a slate fault at all but a failed flashing or a split in the lead. We look at the full path of water, not just the slate nearest the stain. Water can enter at one point and appear on the ceiling metres away, so a stain tells you only where the water arrived.
For the typical cost of repairs, the cost guide we draw on gives typical UK ranges, and our slate roof cost page sets them out. The fixed price we give you follows the survey of your own roof.
Safe access and listed slate roofs
Slate is brittle underfoot. A boot can crack a slate, so walking on the roof makes more repairs than it fixes, and a wet slate is slippery as well. Slaters use roof ladders that hook over the ridge and spread their weight, or work from a scaffold or tower. If you are thinking of climbing up to look at a slipped slate yourself, please read our page on walking on a slate roof first, and use binoculars from the ground if you can. Access is also a real cost: where the slate sits high on a tall house, a scaffold or tower may outweigh the repair in cost.
Repair work on a listed building has an extra layer. In Bath, B&NES expects listed building consent for works affecting a listed building, and a changed roof covering can fall within that. A like-for-like repair of a few slates, using matching material and the traditional fixings, is not the same as swapping the covering, and B&NES asks owners to talk to its planners ahead of any works. The distinction matters, and we would rather you asked than assumed. Our page on listed slate roofs covers the rules and the detail.
Where the roof is not listed but sits in a conservation area, a straightforward repair in matching slate does not normally raise questions. If you are in any doubt, a call to the council's planning team settles it.
Bats and nesting birds have the protection of the law, and both can use gaps under a roof covering, so a find while lifting slates halts the job until we have taken advice. The overall approach to slate work can be seen on the slate roofing hub, which links the survey, repair and re-roofing pages together.