Code 8 Lead is 3.55mm thick(a 12.7% increase over code 7 lead) and weighs 40.26kg/m2 (Thickness to BS EN12588 tolerances of +/- 5%)
If the roof you are working on is on a listed building, historical building or a concert hall or museum, code 8 lead is often used and is suitable for just about every aspect of pitched roofing or flat roofing. Parapet gutters or tapering valley gutters are the applications where the increased gauge of code 8 is most appropriate.
It is worth noting that you may find that the existing configuration was installed before the days of the BS6915 Code of Practice and therefore the bay lengths may exceed current recommended limits.
It is therefore important that the roofing contractor doing the work is experienced enough to recognise and correct the problem, or risk failures resulting from oversized gutters, primarily fatigue cracks.
As with some of the slightly thinner gauges of lead, the increased thickness means that code 7 lead has increased resistance to thermal movement and you can safely keep the maximum length of flashing at 1.5metres. JJ Roofing Supplies standard roll lengths of 3 and 6 metres will therefore give you either 2 or 4 lead flashing strips to work with.
As with all lead work, it is important to use a grey lead sealant that allows for expansion and contraction during heating and cooling, giving a permanent, flexible, waterproof joint which is quicker and easier to use than mortar and helps prevent the mould, rot and other water damage that can result.
As code 8 lead is the thickest of all standard gauges of lead , it is of particular importance to apply patination oil to all the newly laid lead, on the underside of flashing as well as on all exposed surfaces, New lead can develop a corrosion product, lead carbonate, in damp or rainy conditions which leaves a non-adherent coating on the surface of the lead which isn’t pleasant and can provide an area of potential water ingress.
The simple solution for this is the application of a thin coat of patination oil on all newly installed items, ensuring that you get a great looking finish both before and after the final patina develops.