Nail sickness is the most common roofing diagnosis on post-war Inverness properties. It affects thousands of homes across Dalneigh, Hilton, Smithton and Merkinch — and most owners don't know they have it until tiles start sliding off.
Nail sickness is the condition where the galvanised nails used to fix concrete roofing tiles have corroded away, leaving the tiles resting on the roof battens rather than being fixed to them. Tiles held only by their own weight — with no mechanical fixing — can shift in wind, fail to shed water cleanly along the tile laps, and eventually slide down or blow off entirely.
The nails used on post-war Inverness housing were galvanised steel — a zinc coating over steel wire that resists corrosion when new. In the Highland climate, however, decades of freeze-thaw cycling, sustained moisture and the aggressive thermal differential between summer and winter gradually destroy the zinc coating. Once the zinc is gone, the steel rusts. By the time a galvanised nail on a 1960s Inverness roof has been through 60 Highland winters, it's typically a rust flake rather than a structural fixing.
Nail sickness is overwhelmingly a post-war concrete tile problem. In Inverness, the areas with the highest concentration are:
You can identify likely nail sickness without going on the roof:
It depends on the extent of the failure. If nail sickness is localised to one section or one pitch — often the north-facing pitch sees earlier failure due to greater frost exposure — targeted re-battening and re-tiling of that section may be cost-effective.
If nail sickness is widespread across the whole roof — which is typical on pre-1975 Inverness properties — full replacement is almost always better value. Fixing individual tiles on a roof where 80% of nails have failed is like patching individual planks on a boat with a failing hull. The underlying problem remains and the patches won't extend the roof's overall life.
We always survey honestly. If we think repair will do, we'll say so. We don't recommend replacement when it isn't needed.
A full nail sickness re-roof involves: stripping all existing tile to bare rafter, inspecting and replacing rotten battens and any failed sarking, installing modern breathable roofing membrane, fitting new treated battens at correct gauge for the chosen tile, and laying new concrete interlocking tile fixed with stainless steel ring-shank nails. Ring-shank nails won't corrode for 60+ years in Highland conditions — the same issue won't recur in your lifetime.
If you have a Smithton, Dalneigh, Hilton or Merkinch property built before 1980, call us for a free nail sickness survey.
Call 01463 262835Galvanised steel nails in a temperate UK climate typically last 40–60 years before significant corrosion. In Inverness, the Highland frost cycling accelerates this timeline. On the oldest Smithton and Dalneigh properties — roofed in the early 1960s — nail sickness is effectively universal by the time the roof is 55–60 years old. On properties in elevated locations like Culloden and Balloch, where the frost cycle is more severe, we see significant nail corrosion beginning at 45–50 years.
This means that almost all Inverness concrete tile roofing installed before 1975 is now either in or approaching nail sickness territory. If your property was built between 1955 and 1975 and the roof has never been replaced, a survey is warranted regardless of whether you have had a recent leak.
A professional nail sickness survey involves accessing the roof and physically testing tiles across all pitches and elevations. We push individual tiles and assess the resistance — a well-nailed tile will not move under hand pressure, a nail-sick tile will rock noticeably. We assess the percentage of tiles affected on each pitch and map the results.
We also inspect the underlay condition, which on older Highland properties has usually deteriorated alongside the nails. Original bitumen felt from the 1960s is typically permeable or split on roofs with advanced nail sickness — it has been exposed to the same 50+ years of Highland moisture and frost that degraded the nails.
The survey result drives the recommendation: if nail sickness is localised to one pitch or one section (under 25% of tiles affected), targeted re-battening and re-tiling of that section is cost-effective. If it is widespread across the whole roof, full replacement is the correct and more economical answer. We always give you both options with honest pricing for each.
When nail sickness forces a re-roof, material choice matters. For Dalneigh, Smithton and Hilton properties, we recommend:
For Crown, Ness Bank and conservation area properties where nail sickness has been masked by delaminating slates, the choice is natural slate — Caithness where required by planning, Welsh or Spanish for other conservation-sensitive properties.
Nail sickness is not covered by standard home insurance as it is considered gradual deterioration rather than sudden damage. It is not covered by any roofing guarantee from the original installation (those guarantees typically expired 20–30 years ago). It is not the result of any workmanship error — galvanised nails were the correct specification for the era. It is simply age.
The cost falls to the homeowner. The good news is that a full Smithton or Dalneigh re-roof is straightforward work, typically completed in 4–6 days, and brings the roof to a modern specification that should last another 50 years without the same underlying failure mode.
"Dalneigh semi, 1968. Had been patching tiles for three years. Read this guide and booked a survey the same day. Nail sickness confirmed on 85% of tiles. Re-roof done and we've had no issues since."
"The bit about nail sickness progressing faster at altitude was useful — we're in Balloch and the roofer confirmed exactly that. Front pitch was worse than the rear. Replaced both because of the guidance here."
"Recognised the signs from this article — tiles rocking when pushed. Booked a free survey. Got an honest assessment: rear pitch needed replacing, front was still serviceable. Exactly the no-nonsense approach this describes."
Look for tiles out of alignment from ground level, tiles you've had re-fixed more than once, or rocking tiles if you can safely access a lower section. We carry out free nail sickness surveys.
If nail sickness is localised (under 30% of tiles), targeted repair may be viable. If widespread — common on pre-1975 Dalneigh, Hilton and Smithton properties — full replacement is better value.
The Highland climate's prolonged freeze-thaw cycles and high annual rainfall accelerate galvanised nail corrosion faster than in milder UK regions. Original galvanised nails on 1960s–70s Inverness properties have been through 50–60 Highland winters.
No — nail sickness is considered gradual deterioration rather than sudden damage and is excluded by standard home insurance policies. The cost of replacement falls to the homeowner. It is not the result of any workmanship error — galvanised nails were the correct specification for the era.
On an Inverness property at altitude, nail sickness typically progresses from a small affected area to widespread failure within 7–12 years once it begins. The corroded nails that have already failed accelerate moisture cycling in adjacent fixings. This is why we recommend whole-roof assessment when nail sickness is found in one section.
Stainless steel ring-shank nails — grade 316 minimum. Ring-shank nails have significantly higher pull-out resistance than smooth-shank nails, and grade 316 stainless will not corrode within any realistic building lifetime in Highland conditions. This is the standard we use on all re-roofing projects.
Yes, but disclosure obligations apply and surveyors will identify it. A buyer's survey will almost certainly flag nail sickness on a pre-1975 Inverness property with original tile. Many buyers will renegotiate on price or request the roof is replaced before exchange. Getting a roof replacement quote before listing avoids uncertainty.
No call-out fee. No obligation. A straight answer from a local roofer.
01463 262835