Chimney Flashing Repair: Costs and Warning Signs

Flashing is the lead, or on cheaper jobs a lead alternative, dressed around the base of a chimney where it meets the roof. It’s one of the most common single points of failure on an older roof. It is also one of the cheapest things to put right — provided it is caught before the leak it causes does real damage.

A small patch repair, where only a section of lead has lifted or cracked, typically costs around £150–£250. It can usually be done in a few hours (MyJobQuote, 2026). A full replacement runs to roughly £350–£600 if no scaffolding is needed, but £700–£1,200 once it is (Checkatrade, 2026). Scaffolding, at £500–£1,500 on its own, is by far the biggest single factor in the final price. This is why we always try to combine flashing work with any other roof access needed at the same time. It saves scaffolding a roof twice for two separate jobs.

The warning signs are usually visible without going near the chimney. Watch for a damp patch on a chimney breast or ceiling near where the chimney passes through the loft. Flashing failure is one of the most common causes of an internal leak that seems to have “come from nowhere.” From outside, watch for lead that’s visibly lifted away. Grey-white patchiness is a normal ageing process called oxidisation, but it’s a sign the lead is getting brittle. A crack along a fold line is another sign it needs attention. Mortar crumbling from the flaunching, the cement fillet around the chimney pots, is a separate but related issue. It often gets fixed at the same time.

Lead itself is a traded commodity, and its price moves with metal markets, so flashing costs do shift year to year. The labour and scaffolding portion of the bill is usually the larger share regardless. If you’re also dealing with general chimney repointing or a leaning stack, get both assessed together. It’s almost always more cost-effective on the same visit. That’s because the scaffolding cost is shared, not duplicated.

If you’ve spotted a stain near a chimney breast, or can see lifted lead from the ground, in Denny or nearby, our chimney repairs team can assess it. Get in touch through our contact page for a free survey and a clear breakdown of patch-repair versus full-replacement pricing — we cover the same work in Bonnybridge too. We also cover Cumbernauld and the surrounding area.