If your property was built between 1955 and 1985 and you've noticed tiles slipping on the roof — particularly on the rear slope — nail sickness is almost certainly the cause. It's the most common structural roofing problem on Guildford's post-war housing stock and one of the most frequently misunderstood.
Nail sickness is the progressive corrosion of the galvanised steel or iron nails that fix concrete interlocking tiles to the roof battens. Every concrete tile installed on British roofs from the 1950s through to the mid-1990s was fixed with a galvanised clout nail — a short, wide-headed nail with a zinc coating intended to resist corrosion. The zinc coating on most of these nails was adequate for 30–40 years. After that, corrosion accelerates rapidly.
As nails corrode, they lose their grip on the batten. The tile — which weighs 3–5kg — relies entirely on this nail to hold it in place, particularly on the lower courses where wind uplift is greatest. When the nail fails, the tile slips downslope. Initially it moves a few millimetres. Over months and years it slides further, eventually resting on the tile below and leaving a gap above it where water and wind can enter the felt beneath.
Guildford's post-war and 1960s–70s housing stock — concentrated in areas like Park Barn, Bellfields, Stoughton, Burpham and Jacobs Well — was built to the standard specifications of the era. Concrete interlocking tiles were the dominant roof covering, nailed with galvanised clouts. These properties are now 55–70 years old. The nails are at or past the end of their design life throughout these estates.
The Wey Valley suburbs face an additional factor: the higher riverside humidity experienced in Bellfields and Burpham accelerates nail corrosion compared to drier, elevated locations. Properties closest to the river typically show nail sickness 5–10 years earlier than comparable properties on higher ground.
You don't need to get on the roof to identify nail sickness. From the pavement or garden, look for:
The rear slope of a property often shows nail sickness before the front. This is because rear slopes receive less inspection, have often been walked on more frequently (making the problem worse), and frequently face north — which keeps the surface wetter for longer, accelerating corrosion.
There are two approaches depending on the extent of the problem:
Where nail sickness is confined to one slope — typically the rear — the correct repair is to strip the affected slope, remove all old tiles carefully, inspect and replace any rotted battens, and relay the tiles with new stainless steel fixing nails. Stainless steel nails do not corrode and will outlast the tiles themselves. A single slope re-nail on a standard Guildford semi typically costs £600–£950 and should not require attention again for the life of the roof.
Where nail sickness is advanced on all slopes — visible tile movement everywhere — a full re-roof is more economic over five years than completing each slope separately. The decision point is whether the cost of re-nailing all affected slopes in sequence approaches the cost of a complete re-roof. We assess and advise honestly on which applies during a free survey visit.
Important: Repeatedly re-seating individual slipped tiles without addressing the nail condition is not a fix — it is a temporary cosmetic adjustment that leaves the underlying structural problem in place. Each tile that is re-seated manually disturbs the surrounding nails further. The problem returns within months.
Nail sickness is sometimes confused with tile delamination (where the tile surface itself breaks down) or ridge mortar failure (where the ridge tiles at the apex have slipped). These are different problems with different solutions. Nail sickness specifically refers to the fixing failure causing whole-tile slippage — the tile itself is typically undamaged. This is an important distinction: nail sickness on an otherwise sound concrete tile roof does not necessarily mean the tiles need replacing, just re-fixing.
Free survey: If your Guildford property was built between 1955 and 1985 and you're seeing tile movement, call us on 01483 346 440 for a free inspection. We'll confirm whether nail sickness is present, give you an honest assessment of the extent, and quote for the correct repair — not the most expensive one.
Nail sickness is the defining roofing challenge for a significant portion of Guildford's housing stock. The post-war building programmes from the late 1940s through to the 1970s created thousands of concrete tile roofs across the estates of Park Barn, Stoughton, Bellfields, Westborough and the outer residential areas of the town. These properties were built with zinc-plated clout nails that are now 50–75 years old and corrosion is now widespread across the estate rooflines. The most exposed slopes — typically north-west and west-facing aspects that receive the most moisture loading — show nail sickness first, but by the time the exposed slopes are failing visibly, the other slopes have typically progressed well along the corrosion timeline.
In Guildford's Wey Valley suburbs, the nail sickness timeline is compressed by the elevated moisture environment. Properties in Bellfields and Burpham with 1960s concrete tile roofs are showing widespread nail sickness at 55–60 years — the same tiles on elevated Merrow properties are running 5–8 years further before the same condition appears. The persistent moisture in the valley floor accelerates the zinc coating corrosion that drives nail failure, and any zinc-plated nail on a Bellfields or Burpham 1960s roof should be assumed to be at or near the end of its effective service life.
Repair cost depends on whether individual slope re-nailing or full re-roofing is the appropriate response. Slope-level re-nailing with stainless steel nails or clips costs £600–£950 per slope. Full re-roof on a 3-bed Guildford semi in concrete tile costs £6,500–£9,000. For properties with nail sickness on multiple slopes, full replacement is typically more economical than slope-by-slope repair.
Yes — re-nailing or re-clipping with stainless steel fixings without replacing the tiles is viable where the tiles themselves are sound. We strip the tile course, replace corroded nail fixings with stainless steel, and relay the tiles. This gives the tiles another service cycle with secure fixing — typically 25–40 years depending on the remaining tile condition.
It depends on location and condition. A loft inspection that confirms nail integrity — no visible corrosion at nail heads visible from the loft, no tile movement when pressed from above — provides some reassurance. But for any Guildford 1960s or 1970s concrete tile property, a professional survey at ridge level every 3–5 years is prudent given the age of the fixing nails. Call 01483 346 440 to arrange a free survey.
Full re-roof with stainless steel nails or aluminium clips is the permanent solution. Stainless steel fixings are corrosion-resistant for the full life of the tile and eliminate nail sickness as a future maintenance concern. Any re-roof we carry out uses stainless steel fixings as standard — the modest cost premium over zinc-plated nails is clearly worthwhile given the lifespan impact.
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