In this guide

• What BS EN 12588 standardises
• Rolled lead sheet codes at a glance (Code 3–8)
• Best-use cases by code
• Code selector workflow (3 steps)
• Worked examples: chimneys, valleys, cappings, bays
• Build your basket (fast)
• Spec notes: restraint, movement & substrate
• FAQs

Example A — Domestic chimney with stepped abutment

Scope: rebuild flashings at a brick chimney on a slate roof.

1. Select code: Code 4 for the flashing set—stiff enough to keep shape; dressable without fight.
2. Forming & laps: crisp steps and aprons; generous laps with sharp arris at the drip line.
3. Finish: clean and apply patination oil to stabilise the appearance.

In high wind exposure, step to Code 5 for wider aprons to reduce flutter.

Example B — Medium valley on mixed exposure

Scope: valley serving two pitched planes; occasional cross-winds.

1. Select code: Code 6 to form a stable trough with crisp margins.
2. Margins & splash: set deliberate splash laps; add tilt fillets to keep flow within the channel.
3. Outlet: flare transitions; avoid necking a broad trough into a small chute.

See the full design sequence in our valley guide.

Example C — Parapet capping with movement joints

Scope: 300 mm parapet, exposed site, heritage façade.

1. Select code: Code 6 or 7 depending on oversail and wind loading; Code 7 helps retain crisp edges.
2. Movement & restraint: break into bays; use wood-cored roll or cover strips; restrain edges with clips set back from drips (see drips & clips).
3. Façade care: set decisive drips; finish with patination oil to limit streaking.

Example D — Short box gutter bay with leaf fall

Scope: short channel with seasonal debris; occasional choke events.

1. Select code: Code 6 (or 7 where margins need extra stiffness).
2. Sump & outlet: deepen locally; preserve free area at guards; allow realistic cleaning access.
3. Restraint: stainless strip set back from margins; bay breaks coordinated with temperature swing.

More on channels in the box gutters guide.

What does “Code” actually indicate?

It’s a label mapping to nominal thickness and weight within BS EN 12588 tolerances. The benefit is consistent behaviour across batches.

Is Code 4 always right for chimney flashings?

Code 4 is the default for most domestic chimneys. Step up to Code 5 for wider aprons or exposed sites that suffer flutter.

When do I choose Code 6, 7 or 8?

As spans widen, exposure rises or when forming valleys, box gutters and parapet cappings that benefit from stiffness. Heavier codes must be paired with bay breaks and movement joints.

How do thickness and weight affect labour planning?

Higher codes increase mass—plan team lifts, bench forming and secure staging. Use our Lead Weight Chart for load calculations.

Can I mix different codes on one project?

Yes. It’s common to use Code 4 for flashings and Code 6–7 for valleys or cappings. Keep joints compatible and movement design consistent.

Do I need patination oil whatever the code?

Strongly recommended at laps and exposed faces to reduce early staining and improve appearance. See Patination Oil.

Are there regulatory resources I can reference?

For UK practice and regulation context, see Neal Roofing’s overview of BS 6915 and their Leadwork Services.

Which joint type works best with higher codes?

Wood-cored rolls and cover strips both work—choose based on aesthetics, water path and maintenance access.

What’s the quickest way to order the right sizes?

Use the mobile-first Shoppable Lead Chart to click in widths/lengths, add underlay, fixings and finishing oil in one flow.

How do I avoid early staining on stone/brick?

Design decisive drips/oversails (see drips & clips), clean down and apply patination oil after dressing.