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A slipped slate is a slate that has worked loose and slid out of position, usually because its fixing nails have corroded, and on Edinburgh’s traditional slate roofs it needs prompt attention before water gets in. A slate still in place can often be refixed, while one that has fallen and left a gap needs replacing with a matching slate.
At Edinburgh Borders Roofing, we repair slipped slates across Edinburgh, the Lothians and the Scottish Borders, so this guide explains why they slip, how the repair works, and the local factors that matter here.
What is a slipped slate?
A slipped slate has come loose and slid down the roof, leaving it out of line with the slates around it. It may still be resting on the roof, or it may have fallen away completely, leaving a visible gap.
Either way, a slipped slate breaks the watertight surface your roof depends on. Slate roofs keep water out through a careful overlapping pattern, so a single slate out of place interrupts that pattern and gives wind-driven rain a way in. On the steep pitches common across Edinburgh, you can usually spot a slipped slate from the street.
Why do slates slip? Nail sickness explained
Most slates slip because of nail sickness, the gradual corrosion of the nails that hold them in place. When those fixings weaken and fail, gravity, wind and vibration do the rest.
Slate itself is remarkably durable and often lasts a century or more, but the nails fixing it do not last as long. Over decades of damp Scottish weather, the fixings corrode, and this is why an old roof can start losing slates in several places at once. Poor-quality nails used in past repairs speed the process up. High winds off the Firth of Forth, storms and freeze-thaw cycles then finish the job, catching a weakened slate and pulling it loose. This is why one slipped slate on an older roof is often a sign that more will follow.
Refix or replace: how a slipped slate is repaired
The repair depends on whether the slate is still there. A slipped slate that remains on the roof can often be refixed, while one that has fallen and left a gap needs a matching replacement slate fitted.
Because the original nail holes are usually the problem, a slipped slate is normally secured with a slate hook or a lead or copper tab, a strip that holds the slate firmly without relying on the old fixing. This is a proper, lasting repair rather than a bodge. Where a slate has gone altogether, we fit a matching slate, ideally salvaged or closely matched natural slate, so the repair blends in. We avoid roofing mortar or mastic smeared over the gap, which is a common shortcut that fails quickly and looks wrong on a slate roof. This is core roof slating and tiling work.
How a slipped slate repair is carried out
A proper repair follows clear steps, and it starts with safe access and an honest look at the wider roof. One loose slate is often a symptom, not the whole story.
- Inspect. Assess all slipped, cracked or missing slates, and check the condition of the surrounding slates, fixings, mortar and flashings.
- Make safe if needed. For an active leak, apply temporary weatherproofing to stop water getting in until the repair is done.
- Refix or replace. Secure a slipped slate with a hook or tab, or fit a matching replacement where one has gone.
- Check the detailing. Inspect nearby ridge mortar and lead flashings, since these often fail at the same time.
- Final check. Confirm the repair is watertight and the surrounding slates are sound.
When we inspect a slipped slate in Edinburgh, the first thing we check is whether the neighbouring fixings are also failing, because that tells us whether a single repair will hold or whether more slates are on their way down.
Why acting quickly matters
A slipped slate should be dealt with quickly, because the gap it leaves lets water into the roof structure, where it does far more expensive damage than the slate itself. What starts as a minor fix can become timber rot.
Here is the problem: water rarely announces itself straight away. It soaks into the timber and underlay first, and by the time a damp patch appears on a top-floor ceiling, the damage has usually been developing for a while. Catching a slipped slate early is the single best way to avoid a small repair turning into a re-roof. If water has already come through, our roof repairs team can trace the leak back to the fault rather than guessing.
Signs your Edinburgh roof needs attention
The most common warning signs are visible from the ground or from inside the house. Knowing what to look for helps you act before a leak develops.
Watch for slipped, cracked or missing slates visible from the street, slate or mortar debris in the gutters, crumbling or missing ridge and hip mortar, damp patches or stains on top-floor ceilings, staining around chimney stacks or dormers, and daylight showing through in the loft. Crumbling ridge mortar is extremely common on older Edinburgh roofs and is one of the most frequent causes of water getting in, since once it cracks away, wind and rain get under the ridge tiles.
Slipped slates on Edinburgh tenements and shared roofs
On a tenement or shared roof, a slipped slate repair often involves more than one owner, because the roof is shared and the cost is usually divided. This is a common situation across Edinburgh that a local roofer understands.
Responsibility for a shared tenement roof is normally set out in the title deeds, and where owners must share the cost of repairs, this can be coordinated through a property factor or, in some cases, a statutory notice process. It is worth knowing how your building handles shared roof repairs before work is needed. For anything contested or unclear, check your title deeds and speak to your factor. A roofer used to Edinburgh tenements can advise on access and how these repairs usually proceed.
Matching slate and conservation areas
Matching the replacement slate to the existing roof matters for both appearance and performance, and in Edinburgh’s conservation areas it can be a requirement. The right slate keeps the repair discreet and the roof authentic.
Much of Edinburgh sits within conservation areas, and many buildings are listed, particularly across the Old and New Town. In these cases, planners may specify natural slate closely matched to the original, and a reputable roofer will flag this from the outset. Reclaimed or salvaged natural slate is often the best match on a traditional roof. Because the rules depend on your property’s status, it is worth checking with the City of Edinburgh Council where a building is listed or in a conservation area.
Can you repair a slipped slate yourself?
For most homeowners, a slipped slate is not a safe DIY job, because it means working at height on a pitched, often slippery slate roof. The repair itself also needs the right technique to last.
A slate roof is steep and unforgiving underfoot, and Edinburgh’s tenements and villas put many roofs well above safe ladder height. Beyond the danger, a proper refix needs a hook or tab fitted correctly, not mortar or a nail through the face of the slate, which cracks it. This is work best left to a roofer with safe access, which for awkward or tall roofs may mean rope access rather than a scaffold.
Getting a slipped slate repaired
We treat a slipped slate as what it is: a small job worth doing properly, before it becomes a big one. We start with a free photographic roof survey so you can see the slate, the fixings around it and the wider condition of the roof, then we refix or replace as needed and check the nearby detailing.
As an established Edinburgh roofing company, we cover slate, tile, lead and flat roofing across Edinburgh, the Lothians and the Scottish Borders, with rope access for hard-to-reach roofs.
If you have spotted a slipped slate or a gap on your roof, book a free photographic roof survey with Edinburgh Borders Roofing and we will tell you honestly what it needs.
Frequently asked questions
Q1. Why do slates slip on a roof?
Answer: Slates usually slip because of nail sickness, the corrosion of the nails fixing them to the roof. Slate lasts far longer than its fixings, so over decades of damp weather the nails fail, and wind, storms and freeze-thaw then pull loose slates out of place. It is common on older Edinburgh roofs.
Q2. Can a slipped slate be refixed, or does it need replacing?
Answer: A slipped slate still on the roof can often be refixed using a slate hook or a lead or copper tab, which holds it without relying on the failed nail. A slate that has fallen and left a gap needs a matching replacement fitted. Both are proper, lasting repairs when done correctly.
Q3. Is a single slipped slate a problem?
Answer: Yes. Even one slipped slate breaks the roof’s watertight overlap and lets water into the structure, where it can rot timber and cause interior leaks. On older roofs, one slipped slate often signals that the fixings are failing more widely, so it is worth getting the roof checked promptly.
Q4. Who pays for a slipped slate on a tenement roof?
Answer: On a shared tenement roof, the cost is usually divided between the owners, as set out in the title deeds, and may be coordinated through a property factor or a statutory notice process. Check your deeds and speak to your factor. A local roofer can advise on access and how the repair proceeds.
Q5. Should I repair a slipped slate myself?
Answer: For most people, no. It means working at height on a steep, slippery slate roof, which is dangerous, and a lasting refix needs the correct hook or tab rather than mortar or a face nail. It is safer and more reliable to use a roofer with proper access equipment.