How Do You Repair Roof Flashing? A Hampshire Roofer Explains

To repair roof flashing, a roofer removes the failed lead or metal, cleans the joint, dresses new code-appropriate lead into the brickwork, and seals it with fresh mortar or lead sealant. Minor splits can sometimes be patched, but lifted or corroded flashing is usually replaced to keep the joint watertight for the long term.

Below we explain the process in more depth, the different repair methods, and how flashing type affects the work. For the full service overview, see our Roof Flashing Repair page.

What does a professional roof flashing repair involve?

A proper flashing repair follows a set sequence rather than a quick smear of sealant. Skipping steps is the usual reason a repair fails within a season. Here is how we approach it across Hampshire.

• Inspection: We identify whether the fault is in the lead, the mortar, or the substrate behind it.
• Removal: We lift the failed flashing and rake out old, crumbling pointing.
• Preparation: We clean the chase or joint and check the masonry is sound before refitting.
• Dressing: We form new lead to the roof profile, chimney or wall using the correct code of lead.
• Sealing: We wedge the lead into the chase and re-point with fresh mortar or apply lead sealant to the top edge.

Each stage matters. A repair is only as reliable as the joint and masonry it sits on.

How do you fix flashing on a roof? Methods explained

There is no single method for a flashing repair. The right approach depends on the material, the location, and how far the failure has spread.

Patch repair

Where a small split runs along a lead fold line and the surrounding lead is otherwise sound, a targeted patch or dress-in can restore the seal. This suits isolated damage caught early, often a half-day job.

Re-pointing and re-dressing

When the lead is fine but the mortar has crumbled, we rake out the old pointing, wedge the lead back into the chase, and re-point. This is common on older properties where the flashing has simply worked loose over time.

Full flashing replacement

Corroded, torn or repeatedly patched flashing is best replaced. We strip the old material and fit new lead correctly dressed to the abutment, chimney or valley. This gives the most durable result and is covered by our 10-year workmanship guarantee on new installations.

Does the type of flashing change the repair?

Yes. Different flashing details fail in different ways, and each calls for its own method to fix flashing on the roof correctly.

• Chimney flashing: Involves stepped flashing, soakers and a cover apron. Repairs often need the mortar joints raked and re-dressed together.
• Abutment flashing: Where a pitched roof meets a wall, we re-dress the apron into the brickwork chase.
• Valley flashing: The channel between two roof slopes carries heavy water flow, so splits here need prompt attention.
• Skylight and dormer flashing: These have multiple joints and rely on correct overlaps to stay watertight.

Getting the detail right for each type is where hands-on experience counts. Our team brings over 15 years of combined roofing experience to every joint.

How long does a roof flashing repair last?

A correctly dressed lead flashing repair, fitted onto sound masonry, can last for decades. Lead is a durable material when the code weight suits the location and the mortar joint holds it firmly. Repairs fail early when new lead is fitted onto degraded pointing or a crumbling chimney, which is why we always assess the substrate first.

Many chimneys in older Hampshire housing stock – across Portsmouth, Southampton, Fareham and Petersfield – need the pointing addressed before new flashing is fitted. We tell you honestly if that groundwork is needed.

What affects the cost of a flashing repair?

Several factors shape the scope of a flashing repair rather than any fixed figure:

• Whether the fault is a single split or flashing that needs full replacement
• The condition of the mortar and masonry behind the lead
• Access, scaffold requirements and the height of the abutment
• The type of flashing – chimney, valley, abutment or skylight

The most accurate way to understand your repair is a free director-led site survey. We assess the joint in person and give you clear, honest advice with no pressure.

Frequently asked questions

Can roof flashing be repaired or does it need replacing?

Flashing can often be repaired where the damage is limited to a small split or loose pointing. Where the lead is corroded, torn or has been patched several times, replacement gives a more reliable, longer-lasting result. A site survey confirms which is appropriate.

Is sealant a permanent fix for roof flashing?

Sealant alone is a short-term measure and not a substitute for correctly dressed lead and sound mortar. We use lead sealant to finish a top edge, but the seal relies on the flashing being wedged and pointed properly into the chase.

How quickly should you repair leaking flashing?

Promptly. Water tracking behind flashing moves into the loft, timbers and upper walls, so early repair limits the spread. We aim to respond to callouts within 48 hours across Hampshire and the South of England.

Book a free flashing survey in Hampshire

If you have noticed rust streaks, lifted lead or damp on an upper wall, we can assess the flashing and explain your options honestly. We serve Portsmouth, Southampton, Fareham, Gosport, Havant, Waterlooville, Petersfield and towns across the South.

Call us on 02393873756 for a free quote. We respond within 48 hours.

Posted by: Connor Stanley
Date: 5 July 2026