How Long Does Lead Flashing Last?

MyJobQuote's cost guide, last updated on 22 September 2026, states that lead flashing can last for over 80 years. Read that as a figure for good lead in a good detail, not a promise. Length of service and length of cover are separate ideas: one describes how long the material can be expected to work, the other what a contractor stands behind.

Lead lasts because it forms a stable grey surface layer and is soft enough to move without breaking. It does not rust, rot or need painting. Most of the difference between a flashing that survives for generations and one that fails in a few decades comes from five things: the thickness of the sheet, the length of each piece, how it was fixed, the condition of the wall it is tucked into, and the water it has to shed.

Roof position matters as well. A flashing on a sheltered side lasts longer than one on a gable facing prevailing weather, and one beside a flue deals with heat as well as rain. When you are asked how long it will last, the honest answer starts with where it is and how it was made.

Sheet lead is sold in numbered codes, from code 3 up to code 8. A higher number is thicker and heavier. Royston Lead's cast lead brochure gives code 3 as 1.32mm thick and suitable for soakers only, code 4 as 1.80mm, code 5 as 2.24mm and code 6 as 2.65mm. It lists codes 4 to 6 for flashings, and the heavier codes for valleys and parapets.

A thicker sheet has more metal to lose before it wears through, and it stands up better to foot traffic and to the stretch of repeated heating and cooling. The code is not the whole story, however. A code 5 sheet laid in one long piece with no movement joint may split sooner than a code 4 laid in short lengths with proper laps. The way it is held, which our answer on how lead flashing is fixed describes, decides whether the lead can slide.

Valleys carry far more water than a wall flashing and wear differently, so they are judged separately.

Lead rarely wears out on its own. It tends to be cut short by something else. Thermal movement is the biggest: a piece that is too long or fixed too tightly splits at its folds after a few hundred cycles of warm days and cold nights, whichever code it is.

Mortar is another. If the chase pointing crumbles, the top edge drops out and rain runs behind the lead. Moss, leaves and standing water against the metal can also sit in a valley and eat into it over many years. Acidic runoff from some timbers and certain cleaning products can pit the surface.

Poor workmanship counts too, such as a flashing stuck down with sealant, nailed through its face, or laid with a short lap. Theft is a separate risk that removes lead outright. And lead that is thin to begin with simply has less to give.

Many of these causes can be spotted early. A split along a fold, a gap at the top edge or white staining on the wall below all show that the detail is under strain. Catching them in time often means a repair, not a replacement; our answer on whether lead flashing can be repaired sets out which faults can be mended.

You cannot read a flashing's remaining life from its age alone. A hundred-year-old flashing that is flat, tight and unsplit may serve for decades more, while a flashing fitted in the last twenty years can be ready for renewal if it was thin or poorly fixed.

Signs that point to renewal include repeated splits in the same place, large areas of thin or pitted metal, lead that has stretched and sagged, a chase that will not hold wedges, and damp that comes back after repair. If a roof is being re-covered, it makes sense to renew the flashings at the same time, because the old ones sit under the new covering and cannot be got at afterwards without lifting it.

Cost helps with the choice. Checkatrade's June 2026 table lists £50 to £70 per metre to repair lead flashing, with stepped flashing in code 5 at £80 to £120 per metre. Our lead flashing replacement cost answer goes through what moves those numbers, and our lead work page covers the wider jobs.

The survey takes photos of the weak points and ends in a single written price. Email the address with a picture of the flashing you are worried about, and say roughly how long it has been up there.