Code 4 Lead Flashing
(6 Products)Code 4 lead flashing is a type of lead sheet used in roofing and construction for weatherproofing joints and protecting vulnerable areas from water ingress. It is classified according to its thickness and weight, with Code 4 specifically measuring 1.80mm thick and weighing 20.41kg per m².
What is Code 4 Lead Flashing?
Code 4 lead flashing is a specific grade of lead flashing, 1.8mm thick and weighing 20.41kg per square metre. It is designed to be strong enough to provide effective weatherproofing while remaining flexible enough to shape around complex structures.
Manufactured to BS EN 12588 standards, Code 4 lead flashing undergoes a rigorous rolling process to ensure uniform thickness and high quality. Its use is essential in preventing water ingress in buildings, particularly around roofs, chimneys, windows, and walls.
Roofing Applications
- Roof Valleys: Code 4 lead is often installed in the valleys of pitched roofs to channel rainwater efficiently and prevent leaks.
- Dormer Windows: It is used to create watertight seals around dormer windows, ensuring no water infiltration at critical junctions.
- Chimney Flashing: Lead provides long-lasting protection at chimney bases, preventing leaks where the roof meets brickwork.
- Soakers: Small sections of Code 4 lead are placed under roof tiles or slates to provide additional waterproofing.
Other Construction Uses
- Parapet Walls & Copings: Used to prevent moisture ingress in vertical structures.
- Gutter Linings: Code 4 lead is frequently applied to traditional lead-lined gutters to enhance longevity and water resistance.
- Bay Windows & Canopies: Ensures that vulnerable architectural features remain sealed from rain penetration.
Key Properties
- Material Composition: Code 4 lead is manufactured from high-purity rolled lead, ensuring consistent density and structural integrity.
- Manufacturing Standards: It is produced in compliance with BS EN 12588, ensuring uniform thickness and reliability in performance.
- Durability: Lead flashing can last over 100 years, outlasting many alternative materials such as aluminium and bitumen-based flashing.
- Weather Resistance: Lead is highly resistant to corrosion, making it ideal for harsh weather conditions. Unlike synthetic alternatives, it does not degrade under UV exposure or extreme temperature fluctuations.
- Malleability: The natural flexibility of lead allows it to be easily shaped and fitted around complex structures such as chimneys and roof junctions without the risk of cracking.
Installation Best Practices
- Correct Fixing: Lead should be fixed using non-ferrous fixings (such as copper, stainless steel, or brass nails) to avoid galvanic corrosion.
- Allowing for Expansion & Contraction: Lead expands and contracts with temperature changes, so sufficient allowance should be made to prevent buckling or cracking.
- Using Patination Oil: Applying patination oil after installation prevents oxidation and helps maintain the lead’s appearance.
- Correct Overlaps & Seals: Joints should be overlapped by at least 100mm and properly sealed to prevent water ingress.
Frequently Asked Code 4 Lead Flashing Questions
What is Code 4 Stepped Lead Flashing?
Code 4 stepped lead flashing is a weatherproof barrier used where a pitched roof meets a vertical brick or masonry wall. The "stepped" design refers to how the flashing is cut and fitted into the horizontal mortar joints of brickwork in a staggered, step-like pattern.
- Stepped Formation - The lead flashing is cut into sections that match the brick courses, creating a staircase effect as it follows the slope of the roof.
- Embedded into Mortar Joints - Each section is chased (slotted) into the mortar joints and secured with lead wedges to keep it firmly in place.
- Overlapping Design - The overlapping sections ensure that water is directed away from the roof and wall junction, preventing leaks.
- Sealed for Waterproofing –-The top edge of the lead is sealed with mortar or specialist lead sealant to prevent water penetration.
How Long Does Code 4 Lead Last?
Code 4 lead has an exceptionally long lifespan, typically lasting between 50 and 100 years when installed correctly. Its longevity depends on various factors, including exposure to the elements, installation quality, and maintenance.
Lead is highly resistant to corrosion, but pollutants in the air (such as acid rain and salt in coastal environments) can affect its durability. Regular inspections and proper installation using expansion joints to allow for thermal movement will help maximise its lifespan.
What’s the Difference Between Code 3 and Code 4 Lead?
- Code 3 (1.32mm, 14.97kg/m²) - Lightweight, mainly used for soakers and short flashings.
- Code 4 (1.80mm, 20.41kg/m²) - The most versatile and widely used lead flashing, suitable for stepped flashing, chimney flashing, and abutments.
