Wind-driven rain is exactly what it sounds like: rain pushed sideways by strong wind rather than falling straight down. It is one of the most testing conditions a roof faces, and on the west-facing, Atlantic-exposed coasts and uplands of the North West it is a routine event, not a rare one.
Why it behaves differently to ordinary rain
A roof sheds falling rain by overlapping its coverings downhill. Wind-driven rain arrives at an angle — and can even be pushed upward under the laps of tiles and slates, past the edges of flashings, and through gaps that ordinary rain would simply run over. Wind also holds water against a surface for longer, giving it more time to find a way in.
That is why a roof can be watertight for years and then leak in a single storm from the south-west: it is not the amount of rain, but the direction and force behind it.
The roof areas most at risk
- Flashings — driven rain gets behind lifted or tired lead; see damaged flashing.
- Verges and ridges — the exposed edges of the roof take the wind head-on and are prone to mortar cracking and slip; see slipped tiles.
- Chimneys and roof penetrations — anything projecting through the roof creates edges and joints for wind to exploit.
- Older properties — worn mortar and original detailing are more easily breached, common in the region’s Welsh-slate terraces.
Exposure matters as much as the roof itself.
Coastal and upland homes take the brunt of wind-driven rain, so exposed elevations there need more frequent checks than sheltered inland roofs. See the area guides below.
What you can do about it
- Keep ridge and verge mortar sound
- Check flashings and pointing around chimneys
- Make sure tiles and slates are secure at the edges
- Have exposed elevations inspected after big storms
- Related reading: how strong winds damage roofs and how rainfall affects your roof.
- Exposed area guides: Lancashire and Cumbria.
- Worried about an exposed roof? Find a local NFRC member roofer.
Frequently Asked Questions
Wind can push rain sideways and even upward, past laps and flashings that shed ordinary falling rain without trouble. A leak that appears only in windy, wet weather usually points to an edge, flashing or verge that wind-driven rain can get behind.