Nail sickness is the corrosion and failure of the nails holding roof tiles, causing them to slip. It is widespread on Warwickshire's post-war estates where 1960s–70s tiles are now decades old. Individual slipped tiles can be re-fixed, but once failure is widespread, re-roofing with new fixings is the economical solution.
Nail sickness is one of the most common roofing issues across Stratford-upon-Avon's post-war housing stock. Understanding what it is, how to identify it and when action is required is essential for any homeowner with a concrete interlocking tile roof installed before the mid-1980s.
When concrete interlocking tile roofs were installed in the 1960s, 1970s and early 1980s, the standard fixing nail was zinc-coated mild steel. The zinc coating was adequate for the expected lifespan of the tile — 25 to 30 years — but the actual service life of many of these roofs has extended to 45 to 60 years. By this age, the zinc coating has corroded away and the steel nail beneath is actively rusting.
As the nails rust, they expand slightly and eventually lose their clamping strength on the tile. The tile is no longer held firmly against the batten and begins to move slightly under wind load. Over time it slips progressively downward, eventually reaching a point where it is held only by the overlapping tile above, or falls from the roof entirely.
NFRC guidance recognises fixing-nail corrosion (nail sickness) as a primary end-of-life failure mode for mid-20th-century tiled roofs, where the fixings fail before the tiles themselves.
— NFRC technical guidance
The highest concentration of nail sickness risk in our service territory is on the post-war and 1960s–70s estates: Bridgetown and Clopton in Stratford, the south Leamington Spa estates off Rugby Road and Radford Road, Wellesbourne estate housing, and the Birmingham Road fringe in Alcester. These are the areas where concrete interlocking tile was the dominant specification at installation and where the stock is now well into the nail sickness risk window.
Individual nail sickness repairs — mechanical fixing of slipped tiles or replacement of individual tiles — are cost-effective where the problem is isolated to a small number of tiles and the underlying nail population is not yet at general failure. Where nail sickness is widespread — typically when more than 20 to 30% of tiles show movement — a full re-roof in new tiles, battens and stainless fixings is the more economical long-term solution. We confirm which category your property falls into at the free survey stage and show you the evidence rather than simply making a recommendation.
Call 01789 509542 for a free no-obligation survey across Stratford and Warwickshire.
Book a Free SurveyThe primary visible sign from ground level is tiles that have slipped slightly from their original position — they sit lower than the surrounding tiles and show an irregular line rather than a straight course. In advanced cases, tiles may be at an angle or visibly displaced. A professional survey with roof access confirms the extent of the problem across the whole roof.
Yes, where the problem is isolated to a small number of tiles. Mechanical refixing of slipped tiles with new stainless clips or nails is effective where the broader nail population is not yet at failure. Where nail sickness is widespread, continued repair is not economically justified and full replacement is the correct recommendation.
Progressive tile slippage creates gaps in the roof covering that allow water ingress. This typically causes felt underlay saturation, batten rot and eventually ceiling damage internally. Storm conditions accelerate the process significantly — a tile population weakened by nail sickness is far more vulnerable to displacement in high winds than a properly fixed roof.
Not all, but the majority of zinc-coated nail fixings from this era are now at or past the corrosion threshold. The rate of progression depends on the specific nail specification, the moisture exposure of the property and the maintenance history. We assess every property individually rather than assuming replacement is required — some 1970s roofs still have adequate residual nail life for several more seasons of service.
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