Roofing Slate Fixing Methods: Nails and Hooks — What Actually Keeps a Roof On

I keep a broken slate in my toolbox. It came off a Yorkshire roof forty years old, and it's not broken at all — it has two holes where the nails used to be, and around each hole there's a rusty halo. The iron nail grew, the hole grew with it, and one windy Tuesday the slate simply let go. That is the whole subject of this page in one picture: a slate roof isn't fixed by the nail you hammer in today, it's fixed by the nail that's still holding twenty years from now.

I've been fixing and supplying slate for thirty years, and the fixing method is the part most people never think about until a slate slides off. So let's talk nails, centre nails and hooks — what each one is, what each one does, and how you pick the right one for your roof before you spend a penny.

First, get the terms straight: nails, centre-nailing, and hooks

Before we compare anything, here's the vocabulary, because the trade uses the same words differently from the general public.

• Centre-nailed — one nail, driven at the head of the slate, in the area covered by the slate above. This is the classic British method, and the one BS 5534 leans on.
• Double-nailed — two nails at the top corners of the slate, both still in the covered zone. Two grip points mean better resistance to wind uplift; it's the standard choice in windy, maritime areas.
• Hooks (slate hooks) — a metal bracket fixed to the batten that the slate hangs from. No nail pierces the stone, so there's no nail hole to rust. Very common in France and parts of continental Europe; beloved by people who maintain old roofs.

Both nail methods share one rule that overrides everything else: the nails must land inside the headlap area — the part covered by the slate two courses above. If a nail sits in the exposed zone of the slate, rain runs straight down the nail into the roof. That single rule prevents more leaks than any other habit I know.

The quiet killer: nail corrosion, and why the fixing has to outlive the slate

You know how a slate roof is sold as a "100-year roof"? That promise only holds if the fixings also live 100 years. Iron nails, plain steel nails, galvanised nails in a salty coast — these die in five to twenty years, and when the nail goes, the roof goes with it. The slate is the easy part; the fixing is the real commitment.

That's why I always talk about copper nails and stainless steel nails as the only two materials I'll put on a roof I'm responsible for. Copper is the classic — it's soft, it drives clean, and it grows a protective patina instead of rust. Stainless steel is tougher in thin sections and costs less than copper in some countries. The deeper comparison — copper vs stainless, which one for which climate — deserves its own page, and there's one coming on this site; for now, the takeaway is simple: never let a galvanised nail on your slate roof. It's the single most common fix that turns a hundred-year product into a twenty-year one.

The three ways it's actually fixed, and how each one behaves

Let's put the three systems side by side, because "which is better" only makes sense when you see what each one gives you and what it costs.

Read the table the right way: double-nailing is the wind answer, centre-nailing is the traditional answer, and hooks are the maintenance answer. If your roof is on a calm inland slope at 30°, all three will behave. If it faces an Atlantic coast, you'll want double-nailed and probably stainless or copper.

How to choose: three questions that settle it

Every time a customer asks me which method is best, I ask them three things first. Answer these and you'll already be 90% of the way.

1. What's your pitch? Below 22° you want maximum grip — double-nail, or hook plus an adhesive ridge under windy corners. Above 45° almost anything works.
2. Is your site exposed? Coast, hilltop, open field, any roof that catches the wind. Double-nailed stainless or copper, no argument. In a sheltered valley, centre-nailed is fine and traditional.
3. Will you maintain it? Old roofs, heritage roofs, roofs you'll be walking on to swap broken slates every couple of years — hooks win, because one slate comes out in two minutes without lifting the neighbours.

Centre-nailing, the classic British method — in detail

Centre-nailing is the traditional method in the British Isles. One nail goes through the head of the slate, in the covered area, into the batten. The head of the nail is slightly set into the countersunk hole — enough that it doesn't catch the course above, but not so hard that the stone cracks.

Why do so many roofs in England and Wales use a single nail? Because it leaves the top of the slate free to move, and a slate roof is built to have room to breathe. Slate expands and contracts, the building moves, wind lifts the head of a tile a little — and a single centre nail lets the tile hinge instead of transmitting the stress to the stone and splitting it. Two nails on a traditional roof were considered a way to crack slates, which is why so much of English practice kept one.

The trade-off is wind. On a steep, exposed roof, a single nail has to hold everything, and in gale conditions the corners can lift. So the modern British standard (BS 5534) still recognises centre-nailing but says — on high wind or exposed sites, add a second fixing or a wind clip. The logic: tradition held, until the wind changed.

Double-nailing — when two hold better than one

Double-nailing is exactly what it says: two nails at the top corners of the slate, both still inside the headlap zone so both stay hidden. Two points of grip mean the wind can't rock the slate on a single pivot, which is why it's the default in high-wind areas — the Atlantic coast of Ireland, the high moors of England, coastal USA.

The price is subtle: two nails give the slate less freedom to move with the roof. If the two nails are driven hard, the stone has no room to shift and can stress itself over time. The fix is practice, not theory: drive both nails in the top corners, in the headlap, and don't bind the slate — leave the head free so it can sit as the roof breathes. Done well, double-nailed roofs survive storms that shed single-nailed neighbours.

One caution: double-nailing only helps if both nails really are in the headlap. I've seen plenty of "double-nailed" roofs where one of the two holes sat in the exposed zone and leaked for years. Both nails hidden or not worth two nails.

Slate hooks: the fix that doesn't touch the slate

Slate hooks are a European classic that deserves more attention. A hook is a small metal bracket screwed or nailed to the side of the batten; the slate sits in the hook, hanging by its own head. No nail pierces the stone, so there is no rust hole, no nail splitting, and no nail that ages faster than the slate.

The real magic shows up at repair time. With nails, to swap one broken tile you have to lift the slate above it, pull the nails, slide the tile out, and re-drive into a fresh hole or a patched one. With hooks, you reach in, bend the hook tongue, lift the tile out, drop a new one in — the course above never moves. For a roof that's had its moments (forty years of maintenance, a few storms, a few replacements), that's worth a lot.

The downside is wind and batten quality. A hooked slate is held at one point near the head and can lift a bit under suction. And the hook is only as good as the batten it grabs: if the batten is thin or the hook is nailed into the side of a soft batten, the whole system wiggles. So hooked roofs need batten spacing that matches the hook pitch — a detail that puts some installers off.

There's also a third hybrid: hook-and-nail (two hooks plus a top nail) used in very heavy weather on large slates. It's the belt-and-braces approach for a serious roof, and you'll see it on the roofs of Switzerland and Austria.

Two rules that apply to every method

Whatever you choose, these two rules hold on every slate roof I've ever worked on:

1. The fixing must land inside the headlap zone. Every nail, every hook seat, in the part of the slate that's covered by the tile above. Exposed fixing = leak. This is the #1 error on DIY and cheap-contractor roofs.
2. The fixing material must match the slate's life. If your slate is EN 12326 / ASTM C406 graded and expected to last 75–100+ years, the fix must be copper or stainless, not galvanised. Otherwise you've built a beautiful roof on a fuse.

Checking your fixings: what to look for on a roof or in a delivery

Whether you're inspecting an existing roof or checking a delivery of new slate, here's a short checklist that catches most problems:

• Look for rust trails on the face below a nail head — a sign of a nail that's been exposed or is corroding.
• Feel the head of each nail: it should be set, not hammered flat, and not proud enough to touch the course above.
• In the yard, check the pre-punched holes in your new slate: clean, round, with a slight chamfer on the top so the nail doesn't shatter the edge. Holes with rough or chipped edges are a red flag from the supplier.
• Count the nails per slate: 1 for centre, 2 for double — anything else means someone's improvising.
• Check the hooks (if hooked): the hook should sit snug against the batten with no slop; a loose hook will let the tile bounce in wind.

One practical yard check for pre-drilled slate: lay the slate flat, press on the hole with your thumb. If the stone cracks or chips along the hole, it's going to do the same on the roof the first time a storm works it. That's the cheapest quality test there is, and it'll save you a lot of grief.

The one mistake that defeats every method

You can choose the best method in the world — copper double-nails on the perfect gauge — and still lose the roof if the fixing doesn't land in the headlap. On a sloped roof the water runs straight down the slope; it does not run sideways. So a nail one centimetre below the covered edge is one centimetre of water's highway, and it'll leak for fifty years while you blame the slate.

That's why the very first thing I check on any "leaking slate roof" is not the slate — it's the nails. Are they in the head? Are they still holding? Are they rusting? Nine times out of ten the problem is the fixing, not the stone. And nine times out of ten the fix is a proper fixing.

Your 4-point fixing checklist before you order

1. Pick the method by pitch + wind + maintenance — use the questions in this page, not the contractor's habit.
2. Spec the nail or hook material — copper or stainless for the nails; stainless or galvanised-with-ceramic for hooks; never plain galvanised nail in a coastal zone.
3. Confirm the slate is pre-punched with clean, chamfered holes — and that the hole is punched, not drilled into a crack.
4. Match the batten to the method — thickness and spacing for nails, hook pitch for hooks, and always the right batten for the weight of the slate.

If you're ordering slate from a factory (mine, or anyone's), ask them the fixing question before you sign. Any supplier who can tell you exactly which nail or hook goes with their tile, and what pitch their hole is punched at, is a supplier who's thought about the roof — not just the rock.

Frequently Asked Questions

Related Reading

• Roofing Slate Installation Guide — the full sequence where fixing method becomes batten spacing on the roof.
• Understanding Slate Headlap, Gauge and Exposure — the covered zone that every nail and hook must stay inside.
• How Roof Pitch Affects Slate Selection — how the slope steers your fixing choice.
• Slate Roof Repair: Replace Broken Slates — why hooks make repairs easy and nails don't.
• Roofing Slate Products — pre-drilled slate ready for the fixing you specify.