Why Is My Roof Leaking? The 8 Most Common Causes

The eight causes, in the order we find them

Start at the top of this list. On a pitched roof in Buckinghamshire the first four cover the large majority of calls we get.

• ▸Slipped, cracked or missing tiles, often after wind
• ▸Perished or badly dressed lead flashing at a chimney or abutment
• ▸Failed mortar in a valley, verge or ridge
• ▸Blocked gutters overflowing back under the eaves
• ▸Splits or blown laps in an old felt flat roof over an extension
• ▸A leaking Velux or rooflight seal and flashing kit
• ▸Cracked chimney flaunching letting water down the stack
• ▸Condensation in the loft being mistaken for a leak entirely

How urgent is it?

Call today if water is running rather than staining, if it is coming near a light fitting or consumer unit, if a ceiling is bulging, or if tiles have come off in a storm and the felt underneath is exposed. A slow brown ring that only appears in heavy driving rain is usually a flashing or verge issue and can wait days rather than hours, but it will not fix itself and it gets dearer once the timber goes soft.

Why the stain is never where the hole is

Water enters at the fault, runs down the underlay or along a rafter, and drops at the first low point or nail. Metres of travel is normal. That is why we trace a leak from the roof down rather than guessing from the ceiling up, and why a patch applied under the stain almost always fails.

What it typically costs to put right

Most single point repairs (a handful of tiles, a length of flashing, a felt patch) land between £150 and £450. Full chimney flashing renewal in Code 4 or 5 lead is normally a few hundred pounds more depending on access and scaffold. We quote in writing after looking, and every repair carries our workmanship guarantee.

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