Chimneys are one of the most common places for a roof to leak, and it's not usually the chimney itself that's at fault but the junction where it meets the roof covering around its base and sides. Many houses in Bishopston still have their original chimney stacks, even where they're no longer in everyday use for a fire, and getting the weatherproofing right around them is one of the more technical parts of any re-roofing job on this type of property.
The main defence at this junction is lead flashing, which is dressed into the brickwork of the chimney and layered over the roof covering to direct water away rather than letting it track down into the gap between chimney and tiles. On the downslope side of the chimney, a lead soaker or apron handles this job, while on the upslope side a lead back gutter is typically built in to catch water running down the roof above the chimney and channel it around the stack on either side, rather than letting it pool against the brickwork and eventually find a way through.
Getting this detail wrong, or letting old flashing simply be reused without proper inspection, is one of the more common causes of chimney-related leaks on older Bishopston properties. Lead does have a long service life and can outlast several generations of tiles, but it can crack, lift, or come away from the brickwork over decades of thermal movement and weathering, and a re-roof is the natural point at which to renew it properly rather than patching a failing section and hoping it holds.
The brickwork itself also plays a part in how well the flashing performs. Flashing needs to be dressed into a clean mortar joint, known as chasing, so it's held securely and sealed against wind-driven rain from any direction. On older chimneys where the pointing has degraded over the years, this sometimes means a small amount of repointing is needed alongside the flashing work to get a proper, lasting fix, rather than one that will work loose again within a few seasons of being fitted.
Chimney stacks that are no longer in use for an open fire still need this weatherproofing taken just as seriously as an active one, since an unused stack left with failing flashing will let water in just as readily as a working one. Some homeowners choose to have a redundant stack capped or ventilated as part of a re-roof, which can simplify the weatherproofing around it, though the decision on whether to keep, cap or remove a chimney is usually best made alongside the roofing work rather than as an afterthought once the new tiles are already on.
Chimney detailing is exactly the kind of work where experience shows, and it's worth asking any roofer directly how they'll approach it before agreeing to a quote. Brunel Roofing Bristol handles chimney flashing and any associated brickwork repairs as part of a full re-roof, so Bishopston homeowners get a properly weatherproofed junction rather than a quick fix. Get in touch for a quote that covers this detail specifically.
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