Lead Roof: Repair or Replace?

Flashing is the lead worked into the junction of a slope and a wall, stack or roof window, so rain cannot creep in behind it. A soaker is a little bent lead sheet slipped beneath each course of slates or tiles at a wall, steering water back onto the covering. A valley forms where two slopes join at an inward angle, and on many older houses that channel is lined with lead and called a valley gutter. Each job asks something different of the metal, which is why lead comes in numbered codes, and why the same house can carry two or three of them.

Which lead code was used?

The code is a thickness. Royston Lead's brochure sets out which code goes where. Code 3, at 1.32 mm, is listed for soakers only. Code 4, at 1.80 mm, is listed for soakers, flashings, sloping valley gutters and dormer work. Code 5, at 2.24 mm, is listed for flashings, valley gutters, parapet gutters, box gutters and dormers, with the heavier codes 6 to 8 following for the larger gutters. Knowing the code matters when you compare repair with replacement, because thin lead in a place that wanted thicker metal will not last as long as the right code in the same spot.

On a survey we lift an edge where it is safe, check the thickness, and photograph the whole detail, so the picture in front of you matches the one in front of us before any price is written.

A crack in lead is a symptom. The useful question is where it sits and how far it runs. A short split at a bend or a corner, in sheet that is otherwise flat, clean and firmly held, can often be mended with a lead patch bossed into shape and fixed so it sheds water. A crack that runs along a fold, or several cracks across the same sheet, tells a different story.

How do I tell a repairable split from a failing sheet?

Look at the surface around it. Healthy lead is dull grey with a light, even patina. Lead that has been through many seasons of heat and cold can show fine surface crazing, a net of hairline cracks that tends to follow the direction the metal has been trying to move. If the metal beside a split is thin, brittle or pitted, a patch will only move the weak point a few inches along.

It also matters how many repairs are already there. One old patch is part of a roof's history. Three or four patches across one valley mean the sheet has been asked to put up with more than it can, and the next one will probably not be the last.

We show you the photos and tell you which side of that line your lead sits on. Where a patch will hold, we price the patch, and the longer job stays off the table.

Lead swells in warm weather and shrinks when it cools. Across one hot day and one cold night the movement is small, but it repeats season after season, and sheet that is free to slide takes it quietly. Sheet that has been fixed solid across a long run, or cut in one oversized piece, cannot slide. It strains at the fixings and eventually cracks, usually across the sheet and often at a fold or beside a clip.

Why does a newer lead roof sometimes crack before an old one?

Because age is not the only thing that wears lead out. A roof relaid with long unbroken pieces, or with no allowance for movement at the joints, can start to split within a few winters, while a well-laid older valley carries on. When we find cracking across the grain of the sheet with the metal otherwise in good order, the size of the pieces and the joints between them are the first things we check.

That changes the repair. Patching the crack leaves the cause in place, so the patch fails beside the original line. The lasting answer is to cut the lead into pieces that suit the detail, with proper laps and rolls (the raised wooden-cored ribs that join sheets along a run), and to fix them so they can move. That is closer to a relay than a repair, and it is better to know that at the survey than after a second leak.

If the surrounding sheet is sound, a localised fix with correctly sized new pieces may be enough, and we will mark on the photos where the line falls.

Lead is heavy and it hangs on a few small fixings. Clips, which are folded strips of metal that hold the lower edge of a flashing or sheet in place, and nails take the weight and the wind. When they corrode, loosen or go missing, the lead slides, lifts or curls back, and rain gets under it. A slipped fixing can leave a stain that looks like a crack but is not one, so check before you pay for a patch.

Is a loose flashing a repair or a sign of something bigger?

A single lifted edge with sound lead behind it is a repair: refix with proper clips, re-dress the metal and make the joint with the wall tight again. We look at how the top edge is held. Lead tucked into a joint in the brickwork needs the joint to be sound, and where the mortar around a chimney stack has crumbled, new lead fixed to it will not stay put for long. That is why we check the stack as well as the lead.

Slipped lead in a valley, where sheet has crept downhill, can be a sign that it was never held at the top. Pushing it back is a short fix only if it is then fixed so that it stays put.

Sealant is the repair people reach for first. Used alone, it hides the movement for a season and then splits again, and it makes the next proper repair harder because the metal has to be cleaned first. We would rather refix the lead than smear over the gap.

There is a point on every lead roof where repairs stop being the better buy. We look for a handful of signs together rather than one.

What are the signs that lead needs replacing?

Widespread cracking or crazing across a valley or a flat section is the first. Metal that has gone thin, so you can see tears at the edges or see the boards through it, is the second. Repeated leaks in the same place after earlier repairs is the third. A fourth is movement you can see: sheets that have buckled, ridged up or slid, because that tells you the whole detail was not built to cope.

Underneath the lead matters too. If the boards or the timber below have been wet for a long time, they may be soft, and new lead on rotten boards is money wasted. We open the detail enough to see, and the photos show it.

A fully stripped valley or flashing run is a bigger job, but it resets the clock for a long time when done in the right code with sensible sheet sizes. If your lead is on a listed building, or in one of Taunton's conservation areas, the choice of metal and method belongs in the consent conversation. Listed building consent covers works to a listed building that would change its special character, so ask Somerset Council's planning team before swapping lead for another metal. Slate stays slate and lead stays lead where it matters, and the right route is worth finding before work starts.

Published cost guides show roughly what the work runs to, though none of them is our price. MyJobQuote (Sep 2026) lists a small patch on chimney leadwork at £150 to £250, and a full chimney leadwork job at £350 to £920 depending on scaffold. Those are typical UK ranges for one chimney, and they show how much of the figure is access rather than metal.

Why does a small lead job cost more with a scaffold?

Because the scaffold may cost more than the lead. HomeBuilding (Sep 2025) allows about £1,000 for the scaffold on a typical three-bed semi, with permits among it, while MyJobQuote (Oct 2026) quotes £550 to £750 to hire a front-elevation scaffold for a week. A single flashing on a high stack sits at the dear end of that. When a roof needs several repairs at once, doing them together shares the access, which is a good reason to ask for a survey of the whole roof rather than one fault.

Where the scaffold would sit on the public pavement or road, the highway authority has to issue a licence under the Highways Act 1980, section 169. We sort that licence out with the scaffolder, and its cost sits inside the one total.

Beyond access, the price turns on the lead code, the length of the run, the condition of the boards and mortar below, and whether the old lead can be reused or goes in the skip. Ask for a repair and a relay to be priced side by side if you want to compare them. The written total arrives once we have surveyed the roof. The lead work page shows what we cover. Our posts on extending the life of an ageing lead roof and on lead roof maintenance and safety pick up the upkeep side.