Chimney flashing is one of the more vulnerable points on any pitched roof, and in Frenchay, where a good number of properties are older and have established chimney stacks, it's an area worth paying particular attention to during moss removal. Flashing problems can sit quietly hidden for a long time, and clearing moss away is often what finally brings them to light.
Flashing is the material, typically lead or a similar weatherproof strip, that seals the junction between a chimney stack and the surrounding roof tiles, preventing water from getting in at what would otherwise be a vulnerable joint. Because this junction is a natural place for moisture to collect and linger, it's also a common spot for moss and algae to establish more heavily than on the open tile surface nearby.
When moss builds up around a chimney base, it can visually obscure the flashing beneath it almost entirely, filling gaps and softening the outline of the joint in a way that makes it hard to tell, from a distance or even a fairly close look, whether the flashing underneath is actually in good condition.
Once that moss is carefully removed during a proper clean, the flashing is exposed properly, and this is often when problems come to light - lifted edges, sections that have corroded or perished, or gaps that have opened up between the flashing and the chimney or tiles, any of which can be an entry point for water into the roof structure.
This matters because chimney flashing issues are a fairly common cause of leaks that are otherwise difficult to trace, since water can enter at the chimney and travel some distance before showing up as a damp patch elsewhere in the property. Spotting a flashing problem during roof cleaning, before it causes a leak, is a considerably better outcome than discovering it after water damage has already occurred.
For Frenchay's older properties in particular, where chimneys and their flashing may not have been inspected in some years, having this checked as part of a moss removal job is a genuinely useful side benefit of the work, rather than an unrelated add-on.
This is really where having roofing knowledge on site during cleaning pays off - someone familiar with flashing and chimney detailing knows what a healthy joint should look like and can identify when something isn't right, rather than simply cleaning the moss away and leaving the flashing's condition unassessed.
It's also worth noting that flashing issues aren't always immediately obvious even once exposed, particularly to an untrained eye. A small gap or slightly lifted section might look fairly minor on inspection, but depending on its position and the amount of water that regularly runs past it, even a modest defect can allow a meaningful amount of moisture into the roof structure over time. For a Frenchay property with an older or more elaborate chimney design, having flashing properly assessed, rather than just visually glanced at, is particularly worthwhile given how much water such features can channel during heavy rain.
If your Frenchay property has an older chimney and you're due a roof clean, Brunel Roofing Bristol will check the flashing as part of the process and let you know if anything needs further attention.
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