The short answer
Roof tiles lift in the wind because gusts blowing over the roof create suction, and wind getting under the tiles adds pressure from below. A tile held only by its weight and nibs can rise, rattle and sometimes slip off. The common causes are missing or rusted fixings, worn nibs, tiles at the eaves and verge without clips, and gaps that let wind in. Lifting tiles are a warning, because a storm can strip a row at once.
What the wind does to a roof
Wind does not just push on a roof. As it flows over the ridge it creates a region of low pressure on the leeward side, a bit like the effect on an aircraft wing, and the roof is pulled upwards. At the same time, wind that gets in through gaps at the eaves or verge pushes up from below. The two forces together are called uplift, and the edges of a roof see the highest values.
A tile is heavy, but not heavy enough on its own. Uplift in a gale can exceed the tile's weight, especially at the corners and edges of the roof. That is why the standard requires fixings, and why exposed or tall buildings need more of them. Our guide to BS 5534 roof tile fixing explains the standard.
The usual causes
The first is missing fixings. Many older roofs were laid with tiles hung on their nibs and nailed only occasionally, and some have no clips at all. Where fixings are missing, the tile can rise and fall with each gust, and the nibs wear.
The second is corrosion. Nails and clips rust, especially mild steel ones, and the head or shank thins. The tile is then loose without looking it. Our page on nail sickness shows how that develops, and what it looks like in the loft.
The third is the roof edge. The verge, eaves and ridge take the worst of the wind, and a tile there needs a mechanical fixing. Mortar on a verge or ridge dries out, cracks and lets go, which leaves the tiles behind it unsupported.
The fourth is a gap. A missing tile, a broken one or a slipped row lets wind in beneath the neighbours, which then lift in turn. This is how a small fault becomes a stripped slope in a storm.
Why older roofs are more at risk
Many older roofs were laid before the current fixing rules, and a few of them have never had the edges re-fixed. Mortar bedding at the ridge and verge ages and cracks, and the tiles it held lose their support. On a house that has seen decades of weather, the damage builds slowly, and a tile that was snug in the 1970s can be loose by now without anyone noticing.
Trees and neighbouring buildings also change wind behaviour. A new extension or a felled tree can funnel gusts onto a roof that was previously sheltered, so a roof that coped for years can start to lift.
What you can see and hear
From the ground, look for tiles that sit proud of the others, visible gaps, a ragged line along the verge and tile fragments in the garden or on the path. From inside, a rattling noise on a windy night, a whistling sound or daylight in the loft points to loose tiles. After a storm, check carefully. Our answer on what causes slipped roof tiles overlaps with this, because lifted tiles often slip.
If you can, photograph the roof with a zoom lens, and do not climb up to check. See our answer on walking on roof tiles for why.
Why a storm shows up the weak spots
A roof that has stood for years in ordinary weather may show no sign of trouble until the first big gale of the autumn. The wind finds the tile with the worn nib or the rusted nail and lifts it, and the neighbours follow. That is why we advise a look soon after a storm, and before the winter sets in, so the loose ones are dealt with while the weather is still kind to a ladder.
How the fix works
A repair starts by finding why the tiles lifted. We lift a few at the verge and eaves, look at the fixings, check the battens and underlay, and see how the neighbouring tiles are held. Then the repair is matched to the fault: re-fixing loose tiles with stainless nails or clips, replacing corroded fixings, adding clips along the edges, or replacing a dry verge or ridge system. If a whole slope has failed fixings, re-fixing the roof is more effective than chasing individual tiles.
You will see photographs of what we found, and a fixed written quote for the work. Where the work counts as notifiable, we deal with the paperwork for you. More on our tiled-roof service is on the pitched roofing page.
Every roof is different. A free survey with photos settles it for yours.
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