Last updated: August 2026
If the slates on your Victorian or Edwardian roof have started sliding and dropping, the cause is almost always nail sickness. It is the single most common reason a period slate roof in Dublin reaches the end of its life, and it is worth understanding before you pay to have the same slate put back twice.
What Nail Sickness Actually Is
A traditional slate roof does not rely on the slate to hold itself up. Each slate hangs from two nails driven into the batten behind it, and on a Victorian or Edwardian roof those nails were iron. Iron rusts, and after a hundred Irish winters of damp getting at them the nails corrode through and lose their grip. The slate is often still perfectly sound, but with nothing holding it, it slides down the roof and drops. That is nail sickness, and once it starts on one part of the roof the nails everywhere else are the same age and heading the same way.
You usually see it before you understand it: a slate or two on the path after a windy night, a gap on the roof, then another a few weeks later somewhere else entirely. That pattern, slates going one at a time across the whole roof rather than in a single damaged patch, is the tell that it is the fixings failing and not a one-off.
Why Re-Nailing the Odd Slate Never Holds
The tempting fix is to have a roofer put the fallen slate back and move on. On a roof with nail sickness that buys a season at most, because the nails holding the slates on either side of the repair are just as rusted and just as close to letting go. You end up paying for the same roof over and over, a slate here, a slate there, every time the wind gets up, and the running total quietly climbs past what a proper job would have cost.
Worse, every slipped slate leaves a gap, and on a period roof with no felt behind the slate that gap is a clear run for wind-driven rain onto the timbers. Left long enough, a fixings problem on the outside becomes a rot problem on the inside, which is a far bigger bill than the roof you started with.
The Honest Fix: A Re-Roof on New Nails
Where nail sickness has taken hold across the whole roof, the honest answer is a re-roof: the slate comes off, and it goes back on new non-corroding nails that will not rust the way the originals did. It sounds bigger than a repair, and up front it is, but it is the last time you pay for that roof for decades rather than every winter.
- Sound original slate is saved and reused where it matters most, usually the front of the house.
- New copper or stainless nails replace the failed iron, so the fixings outlast the slate.
- A breathable underlay goes on, giving the roof the second line of defence it never had.
- The timbers are checked while they are exposed, and any tired batten or rafter is put right.
The only way to know whether your roof needs a full re-roof or has some life left in a careful repair is a proper look. On a free inspection we can tell you honestly which one you are looking at, and give you a written figure either way.
