The mortar fillet at the top of a chimney stack, known as the flaunching, does a surprising amount of work for something most homeowners have never heard of. It holds the chimney pots upright and in place, and it's shaped to shed rainwater away from the flue openings rather than letting it pool around the base of each pot and work its way down inside the stack.
Because it sits at the very top of the chimney, fully exposed to sun, frost and driving rain, flaunching tends to have a shorter working life than the brickwork beneath it. On older stacks around Kingsdown it's common to find flaunching that has cracked, crumbled, or in some cases separated from the pots entirely, often without any visible sign from the ground unless you know to look for it. Binoculars from the garden, or a photograph taken with a zoom lens, can sometimes reveal cracking that would otherwise go unnoticed until it had already let water in for a season or two.
The consequences of failed flaunching aren't always obvious straight away. Water getting past a cracked fillet tends to track down inside the flue or between the pot and the brickwork, sometimes appearing as damp on a chimney breast a room or two away from the actual chimney, which can make the source confusing to diagnose without getting up close to the stack itself. In some cases the water travels far enough that homeowners assume the problem lies with the roof covering rather than the chimney, and end up looking in the wrong place entirely before the actual cause is found.
Repairing flaunching is usually a more contained job than full repointing or a rebuild, involving raking out the failed mortar around the base of each pot and reforming it with a fresh, correctly sloped fillet. That said, it's worth having the rest of the stack checked at the same time, since flaunching failure is often a symptom of a chimney that's due some wider attention rather than an isolated issue, and the same weathering that cracked the fillet has usually been working on the mortar joints and pots as well.
On disused or capped chimneys in Kingsdown, flaunching still matters even without a fire ever being lit, since a capped flue with failed flaunching can still let water into the stack and, eventually, into the roof structure below. It's a small repair that's easy to overlook precisely because it sits out of sight, and it's often only picked up during an inspection carried out for an entirely different reason.
If your chimney has visible cracking around the pots, or you've noticed damp appearing without an obvious cause elsewhere on the roof, flaunching is worth ruling in or out early rather than assuming the roof covering itself is at fault. Brunel Roofing Bristol can inspect and repair chimney flaunching across Kingsdown, with a free quote provided before any work begins.
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