At the very top of most chimney stacks sits a sloped mortar fillet called the flaunching, whose job is to shed water away from the base of the pots and stop it running straight down inside the flue or between the brick courses. It is not a feature many homeowners in Pucklechurch would recognise by name, but when it cracks or crumbles, the consequences show up as damp problems that can be genuinely confusing to trace back to their source.
Flaunching is exposed to more extreme conditions than almost any other part of the roof, sitting fully open to sun, frost and driving rain at the highest point of the house. Over time it inevitably cracks, and once cracks form, water gets underneath the fillet and can freeze in cold weather, accelerating the damage considerably faster than the original weathering process alone. A flaunching in poor condition often also leaves chimney pots loose or slightly unstable, since the fillet is what holds them firmly in place, which is often the first outward sign that something has gone wrong at the top of the stack.
The tricky part is that flaunching problems are almost invisible from ground level, and even from a ladder it can be hard to judge the extent of cracking accurately, so they tend to go unnoticed until water ingress becomes obvious inside the loft or around a chimney breast. This makes flaunching a good example of a chimney element worth having checked periodically rather than only when a visible problem prompts a call, since a small crack caught early is a far cheaper fix than a fillet that has been letting water in for a couple of winters unnoticed.
Repair involves removing the old, cracked fillet and replacing it with a fresh mortar mix, correctly shaped to fall away from the pots and shed water outward rather than pooling anywhere on the stack. Where pots are loose or damaged, this is usually the sensible point to reseat or replace them, since the flaunching and the pots are worked on together, and separating the two jobs rarely makes sense once access has already been arranged.
Some properties benefit from moving away from a traditional mortar fillet altogether in favour of a lead flaunching or proprietary flue terminal system, particularly on more exposed stacks, though a well-executed mortar flaunching remains a perfectly durable and appropriate solution for most Pucklechurch chimneys when done correctly with a suitably specified mix and proper attention to falls and finish.
If your chimney's flaunching looks cracked, patchy or has visibly loose pots sitting on top of it, it is worth having it inspected before the next round of winter frost does further damage. Brunel Roofing Bristol offers free inspections across Pucklechurch and the surrounding area, with repair work carried out to a 15-year guarantee.
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