A roof tile is heavy enough to feel safe, yet a gale can lift it. Wind passing over a roof creates suction across the slopes, and a tile held down by gravity and a single old nail has little in reserve. Tiles that stay on through a calm winter can come away in one bad night.
The British Standard that governs this is BS 5534. It does not make a roof storm-proof, and it is not a statute. What it does is set out how tiles should be fixed so that the roof resists the wind it is likely to meet. For a house near the Channel, that means asking questions about the site before anyone picks up a hammer: how exposed it is, how steep the roof is and whether anything nearby makes the wind behave oddly.
This guide takes those questions one at a time: what the standard asks for, how a fixing specification is built for a particular site, why shallow roofs struggle, the rule about airports, and a west-coast rule of thumb that gets quoted too loosely. It sticks to what manufacturers and standards say and puts no wind-speed numbers on this coast. Our pitched roofing page covers the wider service.
What BS 5534 asks of a tiled roof
The current edition, BS 5534:2014+A2:2018, deals with slating and tiling for pitched roofs and vertical cladding. Marley is explicit that building to it is not something the law demands. Even so, it is the recognised benchmark for the trade, so a careful roofer works to it, and a roof that fails in a storm will be measured against it. The standard also tells you what to ask for in a quote: how each tile, ridge and verge will be fixed.
The headline change arrived with the 2014 revision. Until then, a ridge bedded on mortar was usually judged acceptable. Marley explains that the revision recognised how little pull-out strength a mortar bed has, and anything bedded is expected to have a mechanical fixing too. A clip, screw or strap works alongside the mortar. Mortar is still used and is not banned; it just no longer works by itself.
One fixing, two fixings
For ordinary tiles the rule depends on how the tile is laid. Wienerberger's guidance sets the minimum for a single-lap tile at one mechanical fixing each. Marley describes the same pattern: single-lap, hip and ridge tiles all secured mechanically whatever the mortar is doing, and each tile on the perimeter secured twice. The edges are where wind pressure peaks, along the eaves, the verge and the ridge, so the second fixing goes where it earns its keep.
Older and heritage roofs
Marley records that the 2018 amendment recognises heritage roofs, where the standard's recommendations may not suit, and tells owners to take advice from the council and from conservation specialists before they decide how to fix. A peg-tile roof on a village cottage is not treated like a new estate.
The site-specific fixing specification
There is no single fixing pattern for every roof in England. Wienerberger explains that a fixing schedule is written for the particular site, taking in its position on the map, its altitude and the local wind conditions. A house on a sheltered cul-de-sac in the Weald and a house on the seafront at Goring do not need the same fixings, even with the same tile.
Marley sets out how the underlying calculation runs. It follows Eurocode 1, BS EN 1991-1-4: begin with the area's basic wind speed, apply a series of factors for terrain, topography, building height and building length, and the result is an effective wind speed and a design wind pressure on the roof. A hilltop, a long terrace and a three-storey block of flats each give a different answer, and so does a gap between two buildings that funnels the wind.
Driving rain as a second test
Wind carries rain with it, and Marley's design procedure treats the two separately. The UK is split into four categories of exposure to driving rain, based on BS 8104 and Building Research Establishment Report 262, for buildings up to 12 metres at the ridge. If a slope is longer than 6 metres, or the site rates as severe, the tile's suitability should be confirmed with the maker.
Nobody can read an exposure category off a postcode. It comes from the calculation for the address, and that is why this guide quotes no category for any town. A written specification for your own site is the only reliable answer, and it is worth asking whoever quotes for a recovering whether one exists.
Why roofs under 30 degrees suffer most
Pitch is the other half of the picture. Marley cautions that when the pitch drops below 30 degrees, the slope facing the gale can end up in strong uplift. A low roof behaves a little like an aerofoil: wind accelerating across the surface drops the pressure on top, and the higher pressure beneath tries to push the covering upwards. Tiles are lifted rather than blown sideways.
That matters on the Sussex coast because so many extensions, bungalow roofs, porches and lean-tos sit at low pitches. Interlocking tiles are made for such slopes, and Marley lists minimums as low as 12.5 and 15 degrees for some profiles. A tile may be permitted on a shallow slope, yet shallow slopes are where it is asked to resist the most uplift. A flat roof rebuilt with a low pitch raises the same issue, and our guide to converting a flat roof to pitched covers the planning and regulation side.
What to do about it
The answer is rarely a different tile. It is a more careful fixing: a nail or clip on every tile rather than every few, sound battens that will hold a fixing under load, and ridges and verges treated as a system rather than a line of mortar. What lies beneath matters too, and the guide to roof underlay and ventilation covers it.
Where a low-pitched slope also runs long, six metres or more from eaves to ridge, the manufacturer's advice is worth having in writing before the tiles are ordered. A long, shallow slope combines the two conditions that Marley singles out, and it is the sort of roof where a standard pattern is least likely to be enough.
Near Shoreham airport: the 6 km rule
Airports bring a different wind problem. Marley warns that the turbulence behind big aircraft, on the way up and on the way down, can load roofs near a runway harder than the BS 5534 calculation predicts. Its guidance points designers to Digest 467 from the Building Research Establishment, and its own rule is simple: if the site is within 6 km of an airport, ask Marley's technical advisory team about the fixing specification.
Shoreham airport stands on land reclaimed from salt marsh beside Old Shoreham, as the Old Shoreham Conservation Area Appraisal notes. A 6 km circle around the airfield reaches a good way along the coast, and depending on where you measure from, the radius could take in roofs across Shoreham, Lancing and Sompting.
We do not put distances against individual streets, because the circle is a matter of measurement from the airfield and the answer for a given house comes from the tile maker. The practical advice is plain: close to the airfield, find out what the manufacturer says about fixing before assuming the usual pattern will do.
What we do with that
If a roof in that area is being recovered or re-fixed, we put the question to the tile maker's technical team before the tiles go on, and the reply is kept with the quote. On a repair, we look at how the existing tiles are held and whether the pattern matches what the manufacturer would advise today. The benefit is a roof fixed for the wind it will actually face, rather than the wind the last roofer assumed.
The west-facing coast rule, and where it stops
One exposure rule gets repeated more loosely than the others. Cupa Pizarras, a slate supplier, puts it this way: as a general guide, land within 30 miles of a west-facing coastline should be treated as highly exposed. It is a rule of thumb for choosing slate headlaps, and a reasonable one for the places it describes.
Our stretch of coast faces south. That is the point on which the rule turns, because it is written for west-facing shores, where weather arrives off open sea across a long run of water. It cannot be stretched to say that everywhere within 30 miles of any shoreline is severe, and the rule settles nothing either way for a south-facing town. We do not use it to label a place, and a customer should be wary of anyone who does so without looking at the roof itself, its height and the ground around it.
That does not make the roofs here sheltered. This coast has driving rain, salt air and gales off the Channel, and a south-facing shore still takes plenty of weather. The sensible reading is that a rule of thumb cannot replace the site calculation. A slope facing open sea, an end-of-terrace house or one on a rise gets assessed on its own terms, and the specification follows from that assessment.
Exposure belongs to the roof
Two houses a street apart can differ in height, aspect, neighbours and pitch. The fixing specification looks at those differences, and the standard expects whoever fixes the tiles to take them into account. That is the case for working from a calculation instead of a postcode.
Ridges, verges and what we check on an exposed roof
On an exposed roof the first things to fail are usually the edges: the ridge along the top, the hips at the corners and the verge, which is the sloping edge at the end gable. They sit where the wind is strongest and they were traditionally fixed on mortar alone. A cracked bed can leave a ridge tile sitting on nothing but its own weight.
Dry-fix systems change that. Dry-fix ridge, hip and verge kits are tested under BS 8612:2018, which Marley describes as the standard that tests them. Passing that test is what a dry system offers over a loose arrangement of clips. The cappings are clipped and screwed to the roof, with no mortar to crack, which suits sea-facing slopes.
On the survey
We look at which tiles are held by a nail, a clip or nothing at all, how the edge tiles are secured, whether the battens will hold a fixing, and how the ridge, hips and verges are anchored. On older clay roofs, our guide to clay peg tile roofs explains why replacement fixings have to respect the original tiles. Survey photographs of the roof itself are shared with you before you agree to anything. A written quote follows, and it states how the ridge, the verges and the exposed rows will be held down.
Where the fix is a small one, a few clips and a re-bedded ridge, that is all we recommend. Where a whole slope was fixed in a way that no longer matches current practice, we explain what fixing it properly involves. Either way, the fixing is chosen for the roof and the site, and the roof is left clear of waste.
