Lead work
The joints where roofs actually leak
Lead seals every junction a roof has: walls, chimneys, valleys, dormers and parapets. It is also the most commonly botched part of a roof, because it is the part that takes a trade skill rather than a pattern.
Lead codes and where they are used
| Code | Colour marking | Typical use |
|---|---|---|
| Code 3 | Green | Soakers and small pieces, where movement is minimal |
| Code 4 | Blue | Most flashings, step and cover flashings, small valleys |
| Code 5 | Red | Valleys, larger flashings, gutter linings, exposed positions |
| Code 6 | Black | Parapet and box gutters, dormer cheeks and roofs, heavier work |
Piece length matters as much as code. Lead expands and contracts with temperature, so a run is worked in individual pieces with laps rather than in one long sheet — this is set out in Lead Sheet Association guidance and the relevant British Standard code of practice.
Lead work we carry out
- Step and apron flashing
- Where a roof abuts a wall, chimney or a neighbouring property, cut into the brick joint and wedged.
- Valley linings
- Where two roof slopes meet. High-wear, high-flow, and the place a failure shows up fastest indoors.
- Chimney work
- Front apron, side steps, back gutter and soakers — four separate elements that have to work together.
- Dormers and bay roofs
- Cheeks, tops and the junctions to the main roof, common on London bay-fronted houses.
- Parapet and box gutters
- Hidden behind a front elevation and invisible from the street until they fill a bedroom ceiling.
- Lead welding and dressing
- Corners and complex junctions formed properly rather than filled with sealant.
How to tell lead work has been done badly
You can assess a lot of it from the ground with a phone camera:
- Mortar fillets instead of lead where a roof meets a wall. They crack, and they are a repair from decades ago that was never right.
- Silicone or mastic along a flashing edge. Sealant is not a substitute for lead being dressed into a joint; where you see it, something underneath is not working.
- A single long run of lead with no laps. It will fatigue and split, usually at the middle.
- Lead that has not been chased into a brick joint but simply bent against the wall.
- A white powdery bloom on new lead — patination oil was not applied, which is cosmetic rather than structural, but it tells you about the care taken.
Lead correctly specified, correctly sized and correctly fixed is one of the longest-lived materials on a building. Most of the lead that fails, fails because of how it was fitted rather than because it wore out.
Lead work we have carried out
Case studies are published here as jobs finish, with photographs taken on site before, during and after the work.
Lead work questions
Can lead be repaired, or does it need replacing?
A split can be lead-welded and a lifted piece can be re-dressed and re-wedged. Where the lead is undersized for its position, or has fatigued along its length, replacing it with the correct code in correctly sized pieces is the repair — patching the same mistake produces the same failure.
Is lead theft still a problem?
It happens, mostly on churches, commercial buildings and large flat areas rather than on domestic flashings. Where it is a genuine concern, security marking and adhesive systems exist. For a typical house, the flashing is not worth stealing.
My roofer wants to use a lead substitute. Is that acceptable?
Sometimes. Flashing substitutes have legitimate uses, particularly on smaller details and where theft is a real risk. They are not equivalent to milled lead everywhere, and on a period property or in a conservation area they may not be acceptable at all. Ask what is being proposed, where, and why.
Not sure what your roof needs?
An inspection ends with a written report and photographs, whether or not you go ahead with the work.
Inspection fee: £99.00.