After the storm: a tile is sitting crooked — how bad is that?

The symptom is familiar: after a windy night a tile sits askew, a piece lies in the garden, or the ridge line suddenly looks irregular. The question is rarely whether something happened, but whether it stops at that one tile.

Why it happens says something about the scope. Dutch meteorological institute KNMI describes wind gusts as brief squalls or gusts of at least 50 kilometres per hour, and speaks of severe gusts from 75 kilometres per hour. A gust does not simply lift a tile: it finds the place where the fixing or the overlap had already stopped doing its job. One shifted tile is therefore more often a symptom of a weakened zone than an isolated incident — and once one tile shifts, the next one lies exposed.

Three possible causes behind the same symptom. One: the anchoring at the ridge or verge has aged (dried-out mortar, corroded clips), leaving a whole row looser than it looks. Two: the battens or the underlay beneath have deteriorated, so tiles lose their support — in which case new crooked tiles appear after the storm without new wind. Three: it really is local, for instance at a detail around a chimney or roof window.

What you can assess yourself: look from the ground, with binoculars, across the whole roof surface for irregularities in the lines — a shifted tile visibly disturbs the straight row. Photograph it, including the wall below, and check the loft for daylight and damp patches. Where it stops is the roof itself: the Dutch labour authority Arboportaal states on measures against fall risk that above 2.50 metres these are legally required, but that below 2.50 metres the employer must also take measures if there is a risk of falling — and a pitched, possibly wet roof surface is no place to take that risk. Have it assessed with a roof inspection (€ 150-350); if it turns out to be limited, tiled roof repair (€ 150-500) is the job. Every guide rate is in the price index.