Why You Cannot Just Nail a Replacement Slate Straight In
If you stand across the street and look at a pitched slate roof—whether on a steep Victorian terrace in Rochester and Chatham or an exposed coastal cottage in Whitstable—you only see the bottom third of each slate. Pitched slate roofs work by double-lapping. Every course overlaps the two courses beneath it so rain can never track through the perpendicular joints between neighbouring slates.
When a roof is first laid, the roofer starts at the eaves gutter and works upwards, nailing each slate directly into the timber batten through two pre-punched holes near the centre or head of the slate. The next course up is then laid directly on top, completely hiding those nail heads from the weather.
When a single slate slips down the pitch fifty or eighty years later, the courses sitting above it are still firmly nailed down. You cannot lift the upper slates far enough to swing a hammer without snapping them. That is why roofers have used hidden mechanical clips—copper tingles and slate hooks—for generations.
Step One: Clearing the Slot with a Slate Ripper
Before a replacement slate can be slid back into its slot, the old broken stubs of the rusted iron nails have to come out. Even if a slate has slid right down into your guttering, the shanks of the two nails that used to hold it are usually still sticking out of the timber batten underneath.
To clear the bed without disturbing the surrounding roof, I slide a long, thin, cranked steel blade called a slate ripper up underneath the overlapping course. The top of the ripper has a hooked notched head. You hook that notch around the old corroded nail shank and strike the handle downwards with a hammer, shearing the old nail cleanly flush with the timber batten.
Once both old nail stubs and any fragments of broken slate are drawn out, you have a smooth, flat channel ready for the replacement slate.
Copper Tingles vs Stainless Steel Hooks: How They Compare
Both copper tingles and stainless steel slate hooks do the exact same job: they anchor into the timber batten through the narrow vertical gap ("perp joint") between the two slates immediately below the missing one, and fold up over the bottom tail of the new slate to stop it sliding down. However, there are practical reasons why I choose one over the other depending on your roof.
1. Traditional Copper Tingles (Straps)
A tingle is a flat strip of soft, malleable copper—usually around 12mm to 15mm wide and cut from 0.6mm or 0.7mm sheet copper.
- How it is fitted: Nailed with two copper clout nails onto the exposed batten in the perpendicular joint between the lower slates. The new slate is slid into place on top of the strip, and the protruding tail of the copper is folded tightly up and over the bottom edge of the slate.
- Best suited for: Older Victorian properties, conservation areas in Faversham, Rochester, or Canterbury, and soft or uneven reclaimed Welsh slates where a flat strap spreads the load gently without point-pressure.
- Appearance: Starts bright copper, then weathers down to a dull dark brown within a few months so it barely shows from street level.
2. Stainless Steel Slate Hooks
Pre-formed wire hooks manufactured from 316 marine-grade stainless steel, often coated in black or dark grey finish.
- How it is fitted: The sharp spiked end is driven directly into the timber batten between the lower slates, and the pre-bent loop at the bottom cradles the lower edge of the replacement slate. Because the wire is rigid, it actively pulls the tail of the slate down against the roof pitch.
- Best suited for: High-wind coastal locations like Sheerness, the Isle of Sheppey, and Herne Bay where fierce estuary updraughts try to lift and chatter loose slate tails.
- Water drainage advantage: The slim cylindrical profile of a wire hook helps prevent capillary action from drawing rainwater sideways out of the joint.
A Trade Tip on Aluminium Tingles and Cheap Galvanised Wire
You will sometimes see budget repairs done using thin aluminium strips or bright zinc-plated hooks. In North Kent—especially anywhere near the Swale or Thames estuaries—salt air eats through cheap zinc plating in a few winters, leaving rust streaks down the roof. Thin aluminium strips are too soft; a single winter gale can bend the tab straight back out, dropping the slate into your conservatory roof or onto the pavement. I only use proper gauge copper or marine-grade stainless steel.
Why Silicone, Mastic, and Expanding Foam Destroy Slate Roofs
One of the worst things I come across when surveying a leaking slate roof in Sittingbourne or Medway is a previous "repair" where someone has pushed a slipped slate back up and squirted half a tube of builder's silicone, lead sealant, or Gripfill underneath it to glue it to the slates below. Even worse is spray foam squirted from inside the loft.
Here is why gluing a slate is a guaranteed way to cause a ceiling leak:
- It dams the water channel: Rainwater is meant to run down the thin vertical gap between two slates and drain safely out over the slate beneath. When someone blobs adhesive under a slate, it blocks that channel and diverts water sideways—straight over the edge of the hidden under-slate and onto your timber battens or ceiling plaster.
- It traps frost: Water pools behind the silicone bead. When temperatures drop below zero in January, that trapped water freezes, expands, and cracks both the repaired slate and the sound slates glued to it.
- It makes future repairs three times harder: Once three or four slates are glued together into a solid clump, you cannot extract a single broken slate with a ripper tool. You end up having to break out a much wider patch of good Welsh slates just to clean up the mess.
If a tradesperson offers to stick a slipped slate back with sealant instead of using a ripper and a copper tingle or hook, do not let them onto your roof.
When Are Tingles Enough—and When Is It "Nail Sickness"?
Copper tingles and hooks are the textbook industry fix when you have lost between one and a dozen slates after a winter storm, or where a scaffold pole or TV aerial installer has cracked an odd slate.
However, if you look up at your roof and see rows of copper tabs glinting across every third course—a look roofers call "confetti"—it means your roof is suffering from widespread nail sickness. All the original nails across the roof were hammered in during the same week a century ago, and they are all rusting through at the same pace.
Remember that a copper tingle transfers the weight of the repaired slate onto the batten and slates immediately below it. You cannot safely hang a tingled slate onto another tingled slate. Once more than roughly 15% to 20% of a roof pitch has failed through nail corrosion, paying for individual call-outs every winter becomes false economy.
At that point, the honest recommendation is a full strip and re-cover. If the natural Welsh slates themselves haven't gone soft or delaminated, we can often strip the roof carefully, salvage up to 75–80% of your original slates, install modern breathable membrane and treated timber battens (upgrading your loft insulation to comply with Building Regulations Part L where more than 25% of the roof is stripped), and nail the slates back down with heavy-duty copper clout nails so they stay put for another eighty years.
Common Questions About Slipped Slate Repairs
Why is there a small metal clip showing at the bottom of my new slate?
That small folded tab is the copper tingle or stainless steel hook holding the replacement slate in place. Because the top of the slate is tucked under the existing course above, the bottom edge must be supported mechanically to stop gravity pulling it down into the gutter.
Can you reuse the slate that slid into my gutter?
Provided it landed intact in the gutter and hasn't split, cracked across the middle, or gone flaky around the edges, yes—reusing the original slate ensures an exact thickness and colour match. If it smashed on the patio, I keep reclaimed Welsh slates (such as Penrhyn and Bangor Blue) in standard imperial sizes on the van to match it properly.
Do you need full scaffolding just to fix two slipped slates?
On most two-storey houses and bungalows with safe ladder footing, I can carry out minor slate repairs using a roof ladder and staging without the cost of full scaffolding. If the roof is a tall three-storey Victorian terrace right on a busy pavement, or near a fragile dormer valley, we will discuss access honestly when I inspect it from the ground.