What a lead code actually tells you
A lead code is a number that stands for a thickness and a weight, and a higher code is thicker and heavier. Each code also has a colour mark, so a roll can be identified on site without anyone measuring the edge of the sheet.
The code belongs to the sheet, not to the job. The same Code 4 sheet could be cut into a flashing in one place and a lining in another. What settles the code for a given detail is the specification, the written description of the sheet, the work and the fixing.
For a homeowner, that means a quote that only says "lead flashing" is saying less than it seems. The thickness is one of the things that separates one price from another, and it is worth seeing in writing. Lead sheet work follows BS 6915 through Approved Document C, and the specification applies that standard to your building. The six codes in the Royston Lead brochure follow in the next section, and our lead roofing page describes the work they cover.
The six codes in the Royston Lead table
| Code | Thickness | Weight | Colour mark |
|---|---|---|---|
| 3 | 1.32 mm | 14.97 kg/m² | Green |
| 4 | 1.80 mm | 20.41 kg/m² | Blue |
| 5 | 2.24 mm | 25.40 kg/m² | Red |
| 6 | 2.65 mm | 30.05 kg/m² | Black |
| 7 | 3.15 mm | 35.72 kg/m² | White |
| 8 | 3.55 mm | 40.26 kg/m² | Orange |
The table shows what each code is. It does not say which code belongs to which detail on your roof, and nobody should read it as if it did. Only the specification can do that. Two quotes can both say lead and still mean different sheets, so the code is worth reading before the price.
Reading down the table, thickness rises by about half a millimetre or a little less with each step, from 1.32 mm at Code 3 to 3.55 mm at Code 8. Weight rises with it, from 14.97 kg/m² to 40.26 kg/m².
The brochure's list of uses runs from soakers and flashings to valleys, dormers, flat roofing, parapet walls and work on historic or listed buildings. The breadth of that list is the reason a single code cannot cover it.
Code 3 is for soakers only
One use is stated plainly in the brochure's "Used for?" table, which gives Code 3 as "Recommended for lead soakers only". Soakers are small, sit under the covering and are bent into a tight L, so a thin sheet that folds cleanly suits them.
A soaker is the small L-shaped piece of lead laid with the tiles at a chimney or wall, as described on our what are lead soakers page. It is shielded by the covering and cover flashing, which is why a thin sheet can do the job.
The reverse does not hold. Code 3 is a soaker code and nothing wider, so it should not turn up against cover flashings, valleys or flat areas. If a quote proposes Code 3 for an exposed detail, ask why and ask to see the specification.
Beyond that, the code for each detail comes from the specification. A code picked from a chart on a web page is no substitute for one chosen from a specification that fits your roof, its exposure and the standard it must meet. The cover flashings that sit over soakers are described on the stepped lead flashing page.
What to ask for in writing
If you are comparing quotes for leadwork, three questions make the comparison fair.
- Which code of lead is allowed for each detail: soakers, cover flashings, valleys and any flat area?
- Will the code be marked on the rolls delivered, so it can be checked on site?
- Does the specification say which standard it follows?
A roofer who has measured the work should be able to answer these without hesitation. If the answer is a general phrase such as "thick lead", the quote is leaving the choice to be made later, and that is where prices diverge.
Citizens Advice points to getting at least 3 written quotes. Make sure each one names the code against each detail, so the three can be compared like for like, and ask any trader who leaves it out to add it.
On our side, the specification is agreed with you before work starts, with the code named detail by detail. For repairs to existing lead, the lead flashing repairs page shows how a smaller job is scoped. Even a small repair benefits from a short written note of what sheet will be used and where it goes.
