Lead is the most durable roofing metal in domestic construction — correctly specified and installed, it should last 60-80 years. But coastal North Wales is one of the most demanding environments for lead, and specification matters enormously.
Airborne salt from the Irish Sea creates a surface oxidation environment that degrades lead flashings approximately 30-50% faster than sheltered inland sites. A lead flashing that would last 60 years on a sheltered Cheshire property may last 35-45 years on a Llandudno promenade elevation.
Key fact: Sheet lead for building work is manufactured and coded to BS EN 12588, with codes 3 to 8 denoting increasing thickness. Source: BS EN 12588 (rolled lead sheet)
| Code | Thickness | Use |
|---|---|---|
| Code 3 | 1.32mm | Individual soakers only |
| Code 4 | 1.80mm | Step flashings, apron flashings |
| Code 5 | 2.24mm | Back gutters, wide aprons, all coastal applications |
| Code 6 | 2.65mm | Lead valleys, large flat areas |
| Code 7 | 3.15mm | Parapet gutters, flat roofs |
On Llandudno's exposed coastal properties, we specify Code 5 in most applications where Code 4 would be standard inland. The additional cost is small relative to the extended lifespan.
New lead oxidises on exposure to atmosphere. In the salt-air environment, aggressive salt oxidation can interfere with the formation of the stable protective patina, producing instead a soft, soluble oxide that continues to erode. Patination oil, applied at installation, promotes the formation of the stable protective patina regardless of the salt-air environment. We apply patination oil as standard on all new lead in the coastal salt-air zone.
Lead flashings are pointed into a mortar bed cut from the masonry course. In period properties, this pointing should be NHL lime mortar — compatible with the lime mortar in the masonry, flexible enough to accommodate movement without cracking. Silicone sealant fails within 5-7 years, often trapping moisture behind the failed seal. We use NHL lime mortar on all flashing pointing as standard.
We inspect all lead details as part of every free roof survey. Call 01492 339 101.
📞 Call 01492 339 101Correctly specified and installed Code-grade lead with patination oil should last 40-60 years in Llandudno's coastal environment — approximately 30-40% less than the 60-80 years achievable in sheltered inland locations.
Temporary repair with lead-compatible tape is acceptable as an emergency measure. Permanent repair requires replacement of the affected lead — sealant degrades in the coastal environment and will fail within 3-7 years.
Signs: active water ingress at the flashing position, mortar pointing that crumbles when touched, visible gaps between flashing and masonry or tile, lead with extensive surface pitting, or lead that has cracked at the dressed edge.
Lead is installed in sections of no more than 1.5 metres to allow thermal expansion and contraction without stress fractures at folds. Each section is fixed with a lead clip at the top and allowed to move freely below. The section is dressed (shaped) against the adjacent masonry or tile surface using a wooden dresser — never a metal tool, which marks and work-hardens the lead. At the base, the lead is dressed over the tile or slate surface with a minimum 150mm overlap. These are standard details to any experienced lead worker; the frequency with which we encounter incorrectly installed lead on Llandudno properties suggests they are not universally understood.
On Llandudno's exposed coastal properties within approximately one mile of the North Shore promenade, we specify Code 5 lead (2.24mm) in most applications where Code 4 (1.80mm) would be standard inland. The additional material cost is typically £30–£80 per chimney stack. The difference in lifespan in Llandudno's salt-air environment is estimated at 15-20 years. Over the life of the installation, Code 5 is the more economic choice on coastal sites.
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