Failed lead flashing is the single most common cause of roof leaks on Tonbridge period properties — and the most frequently misdiagnosed. Two roofers patching the wrong thing, and the flashing fails again inside a year. We specify and install lead correctly — correct code, correct laps, correct dressing — so it doesn't need revisiting.
Lead flashing repair and replacement on all Tonbridge property types — chimney aprons, step and soaker flashings, valley lead, dormer junctions and abutments.
The apron flashing at the base of a chimney stack is the most common lead failure point in Tonbridge. North-facing stacks experience more frost cycling, more UV degradation and less drying out — all of which accelerate lead fatigue at joints and welts. We strip failed aprons back to brick, chase new lead into the mortar joint correctly and dress it to the tile surface.
Step flashings up the side of a chimney stack and soakers under each tile course are often installed incorrectly by non-specialists — soakers too short, steps not lapped correctly, or cut lead re-used. We install to BS EN 12588 specification.
Open lead valleys on period Tonbridge properties — particularly on Victorian detached houses with complex roof lines — are a high-priority repair when the lead develops splits or the laps open up. We replace full valley runs rather than patching, using correctly weighted Code 5 lead with correct welted joints.
Dormer cheeks and sill flashings on Tonbridge loft conversions are a regular repair call — often installed cheaply during the original conversion and now at the end of their life. We replace all dormer lead elements to correct specification.
Where a lean-to roof meets a house wall, the abutment flashing is under constant thermal stress. Failed abutment lead is a common cause of damp in single-storey rear additions — we strip, repoint the chased joint and re-dress correctly.
If you have a suspected lead failure but don't know where, we carry out lead surveys across the whole roof — chimney, valleys, dormers, abutments — and report in writing on the condition of each element with a prioritised repair plan.
Tonbridge's period housing stock — Victorian terraces off Pembury Road, Edwardian semis in Dry Hill Park and Barden Road, the older properties around the castle — carries lead flashing that in many cases was installed 60–100 years ago. Lead has a very long theoretical lifespan when installed correctly, but the actual lifespan is significantly reduced by thermal cycling, frost damage to the chased mortar joint, and the mechanical fatigue that comes from a lead sheet that was under-weighted for the application or dressed without adequate drip provision.
The Medway Valley humidity means that on north-facing Tonbridge chimney stacks, lead that is perpetually damp experiences faster oxidation and more aggressive frost cycling than equivalent south-facing elements. The most common failure mode we see on Tonbridge Victorian terraces is a split or lifted apron flashing where the lead has fatigued at the welt, often combined with a failed mortar joint in the chase above — allowing water to track both under the flashing and through the joint simultaneously.
A correctly installed lead flashing system on a Tonbridge property, using Code 4 lead for soakers and Code 5 for aprons and valleys, with joints welted rather than lapped, and chase pointed in a flexible mortar, should last 40–60 years. The most common reason lead fails prematurely is under-specification — Code 3 used where Code 4 or 5 is required, or a flat welt that opens under thermal expansion. We install to specification and provide a written 10-year workmanship guarantee on all lead work.
Typical ranges. Free written quotes on 0173 224 1138.
| Job Type | Typical Cost | Duration |
|---|---|---|
| Chimney apron flashing (small chimney) | £250–£450 | Half day |
| Step & soaker flashings (full chimney) | £400–£700 | Full day |
| Valley lead replacement (per metre run) | £120–£180/m | Full day |
| Dormer flashing (cheek + sill) | £300–£600 | Half–full day |
| Abutment flashing (lean-to) | £200–£450 | Half day |
| Full lead survey + report | £150–£200 | 2–3 hrs |
"Lead apron on a north-facing Victorian chimney had been leaking for three years — two roofers had patched it without fixing the cause. These guys stripped it back, explained exactly what had failed and why, replaced to Code 5 with a welted joint. No leak since. Should have called them first."
"Valley lead on a detached Victorian property — full valley run had splits and the laps had opened up. Replaced the entire run, Code 5 throughout, correctly welted. Expensive but correctly done. Five-star job."
"Dormer flashing on a 10-year-old loft conversion had already failed — original installation was poor. They replaced all dormer lead elements to correct spec. Wish the original builder had done it right, but at least it's right now."
Code 5 (1.8mm, 25kg/m²) for apron flashings. Code 4 for soakers. Code 5 for valley lead. Using Code 3 (1.2mm) on exposed elements is the most common cause of premature failure we encounter.
Correctly specified and installed lead should last 40–60 years. The Medway Valley climate means north-facing elements are at the lower end of that range. Incorrectly specified or installed lead may fail within 10–15 years.
Small splits or lifted joints at non-structural positions can be repaired with lead sealant or lead clips. Where the lead has fatigued across a larger area or the welt has opened, replacement of the full element is more reliable and cost-effective.
Chimney apron: £250–£450. Full chimney with step and soakers: £400–£700. Free quotes on 0173 224 1138.
If the lead has split at lap joints or is pulling from the chase, repair may extend life. If it is undersized (Code 3 on an exposed position), the correct fix is replacement in Code 5. We diagnose on-roof before quoting.
Code numbers refer to lead weight per m²: Code 4 is 1.78mm thick, Code 5 is 2.24mm. Code 5 is the minimum for apron and step flashings on Tonbridge exposed chimney positions. Code 3 — commonly installed — is too thin for sustained weather loading and fails within 10–15 years.
10-year written workmanship guarantee on all lead work we carry out in Tonbridge. Correct specification is also the best long-term guarantee — Code 5 with welted joints lasts 40+ years.
Free inspection, written quote, no obligation.
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