The short answer
MyJobQuote says correctly installed lead flashing can last over 80 years, and over 100 years for higher codes. Less gives 50 to 100 years for a lead flat roof. These are typical ranges, not promises. Thickness, fixing, movement, exposure and maintenance can bring a lead roof down well short of them.
What the published figures say
Two sources give useful numbers, and they cover slightly different things. MyJobQuote's guide to chimney leadwork (22 September 2026) puts flashing laid to a good standard at more than 80 years, and more than 100 for the higher codes. The cost guide from Less (updated March 2026) lists a lead flat roof at 50 to 100 years.
The two ranges overlap, and the lower bound of the flat roof is a sensible reminder that a lead roof is not a single object. A flashing at a chimney and a covering over a flat roof face different conditions: one is a narrow strip fixed at the edges, the other is a whole sheet that takes the weather directly.
Please read these as typical ranges across the UK. They describe what a well-made job can reach, they do not guarantee what any one roof will do, and a lifespan is not a warranty.
Why thickness and code matter
Rolled lead comes in codes, a number from 3 to 8 that corresponds to thickness. According to Leadworx, Code 3 is 1.32 mm, Code 4 is 1.80 mm, Code 5 is 2.24 mm and Code 6 is 2.65 mm, with thicker codes above that. Thicker sheet has more metal to wear away, so it tends to last longer, which fits the MyJobQuote point about higher codes.
Leadworx names Code 4 as the usual pick for general flashing, while Code 5 and above suit wider flashings, valleys and gutters where there is more stress and more water. Choosing a code too thin for the position is a common reason a lead roof ages early. Our page on the lead saddle shows one detail where thickness and shaping matter.
The details around the lead matter as much as the lead. A sheet cut in bays that run too long, or fixed too tightly, will crack well before the metal wears out. That is the subject of the guide to why lead cracks.
What shortens the life of lead
Thermal movement is the main enemy.
The effect builds slowly. Each warm day lengthens a sheet by a tiny amount and each cold night pulls it back, and lead does not return fully to its old shape. Over many seasons the metal creeps downhill, thins at the folds and eventually splits along the line of greatest stress. A sheet that is allowed to move, with short bays and free-sliding clips, ages far more gently than one pinned in place. Lead expands in the sun and contracts at night, and over decades the repeated movement leads to fatigue cracking, particularly where the sheet is restrained. Poor fixing, long bays and rigid joints make that worse.
Foot traffic, tools and dropped objects dent and thin the sheet on flat roofs and gutters. Bird droppings and acidic leaf debris can stain and slowly attack the surface. Contact with some wet timbers or fresh mortar can cause corrosion on the underside, which is why a barrier layer or a proper underlay is used.
Finally, theft shortens a lead roof's life dramatically, with thin replacements often fitted in haste afterwards. Any survey should look at the overall condition of the roof, not just the metal. Our pages on lead safety and leadwork explained give context for the detail that follows.
Flashing is not the same as a lead roof
A house can have lead flashings at its chimney and walls while the main roof is slate or tile. The slates may have been relaid more than once while the lead has stayed put, or the lead may fail first because it was thin or poorly fixed. The covering and the metal are separate questions.
A lead flat roof, such as a bay roof, porch or a small dormer, is built from large sheets joined by rolls or drips, which allow movement. Lead flat roofs have a long record, and a good number of Victorian examples are still doing their job. Their failure points are usually the joints and the edges, not the middle of the sheet.
On a survey we tell you which parts of the lead are original and which are repairs, and where the metal has thinned. A written quote follows, and if we replace lead, the work is covered by our 10-year workmanship guarantee in writing.
Checking your own lead, and when to ask for help
From the ground or a safe window, look for white or grey powdery patches, which are normal oxide, and for cracks, lifted edges, lead that has crept down the slope or ripples that suggest it has stretched. Dark stains below a flashing show where water has been running. A bulge in the lead near a chimney means it has slumped.
Inside, a damp patch on a ceiling or chimney breast after rain is the usual first sign. Leave the climbing to a professional. A roofer can check with a camera pole or from a tower, and our survey photographs show the detail at close range.
Where the lead is sound, clearing debris from time to time and checking it after storms is enough, and it is worth keeping an eye on any section that carries foot traffic, since maintenance visits are where dents and scuffs are most often made. Where it is failing, we will tell you whether a repair will do, as set out on the lead flashing repairs page, or whether new metal is the better answer. Everything we do with the metal is under lead roofing.