Ely Roofers installs and repairs lead flashings in Bar Hill using code 4 and code 5 lead sheet, giving homeowners an honest steer on which materials suit their roof.
Lead flashing is the weatherproofing seal at every junction on a roof where a flat surface meets a vertical one. Chimneys, dormers, parapet walls, abutments where a roof meets a house wall, and open valleys where two roof slopes meet - all of these rely on correctly fitted lead to keep water out. When any of these joints fail, the result is usually a persistent, hidden leak that causes damage well before it becomes obvious inside the property.
Choosing the right material for each part of the job matters. Below is an honest rundown of the main options available to homeowners in Bar Hill, along with the situations each one suits best.
Code 4 lead is 1.8mm thick and weighs approximately 20kg per square metre. It is the standard minimum weight used for most step flashings, cover flashings and chimney aprons on domestic roofs. It is easier to dress (shape by hand around corners and profiles) than heavier codes, which makes it well suited to complex chimney stacks where the flashing needs to follow intricate brick courses.
Pros: Lighter weight means less stress on fixings and pointing; easier to work with on detailed profiles; lower material cost than heavier codes; adequate service life when installed correctly in sheltered or standard positions.
Cons: Work-hardens faster than code 5 in exposed positions; not recommended for wide valley gutters or large flat areas where pooling water could be a factor; shorter service life than code 5 in very exposed locations.
Code 5 is 2.24mm thick, weighing around 25kg per square metre. It is the preferred specification for chimney back gutters, wide valley gutters, parapet gutters and any location where the lead needs to hold standing water or withstand repeated foot traffic during maintenance. Many specifiers and experienced roofers use code 5 as their default even for standard chimney flashings, as the additional thickness buys a longer service life.
Pros: Greater resistance to work-hardening and cracking; better suited to valleys and gutters where water lies for any period; more durable in exposed or high-wind positions; the preferred choice where longevity is the priority.
Cons: Heavier and slightly harder to dress around tight profiles; higher material cost; on complex chimney stacks with many angles, fitting takes a little longer than code 4.
In practice, code 5 is rarely the wrong choice on a domestic roof, and the difference in material cost per flashing is modest. If you are having a chimney done and plan to stay in the property for many years, it is worth asking for code 5 throughout.
Several alternative flashing materials are sold as substitutes for lead. It is worth understanding what they are and where they do and do not work.
Aluminium flashing tape and roll. Aluminium flashing systems are used by some roofers as a quicker or lower-cost alternative, particularly on small repairs. The best-quality aluminium flashings, correctly installed and primed, can perform adequately in straightforward situations. However, they do not have the same service life as dressed lead, and they are more vulnerable to damage in exposed positions. They are not suitable for valley gutters or anywhere water needs to be managed across a larger area.
Lead-look mortar fillets. A mortar fillet is sometimes used at the junction between a roof slope and a wall instead of a proper flashing. It can look acceptable when newly pointed, but mortar is brittle and cracks with movement. It is not a waterproof solution and should not be used as a permanent replacement for dressed lead. If you see a mortar fillet at a chimney or abutment, treat it as a temporary measure that needs replacing.
EPDM rubber strip and butyl tape. These materials are sometimes used on flat roof upstands and perimeter details. For flat roofs they have a place, particularly as a secondary seal, but they are not a substitute for lead at chimney flashings or tiled valleys.
For most residential jobs in Bar Hill, dressed lead sheet - code 4 or code 5 as appropriate - remains the most reliable and cost-effective long-term solution. It is the material that experienced roofers use when they are not cutting corners.
Lead sheet for building work is covered by BS EN 12588. This sets the alloy composition and dimensional tolerances for the sheet itself. The installation standard that roofers follow is published by the Lead Sheet Association and covers details such as maximum section lengths (no more than 1.5 metres per piece, to allow for thermal movement), fixing methods, lap dimensions, chase depths and mortar types.
Installing lead to these standards is not optional if you want the work to last. The most common reason lead fails prematurely is sections that are too long - one continuous strip of lead across a chimney will buckle and crack because the metal cannot accommodate the thermal expansion. Correctly jointed sections with proper clips and wedges will outlast any bodged single-piece fix by many years.
A roofer who cannot answer these questions clearly, or who quotes a very low price without explaining the specification, is worth treating with caution.
We carry out lead flashing installation and repair for homeowners in Bar Hill and the surrounding area. If you want an honest assessment of what your roof needs and a clear explanation of the options, call us to arrange a roof survey.
No obligation · We usually respond within 2 hours
Storm damage, active leak, damaged ridge - we aim to be on-site within 24 hours.
