15kg - 6metre Rolls: 230mm, 300mm, 350mm, 450mm, 600mm 20kg - 6metre Rolls: 230mm, 300mm, 350mm, 400mm, 450mm, 600mm 15kg rolls are not always kept in stock - may require additional dispatch time. Lead sheet is an ideal material for roof flashing. It has the: SOFTNESS AND DUCTILITY to be dressed down on-site to closely fit roof contours, without splitting or cracking. WEIGHT to prevent lift or shift in strong winds. DURABILITY to withstand years (even centuries) of exposure to the atmosphere in all sorts of environments. To make the most of Quality Lead for roof flashing, certain properties and characteristics of the material need to be considered. The thickness of lead sheet has traditionally been expressed as a mass per unit area. This convention was retained on metric conversion and the unit that applies now is kilograms per square metre. Lead sheet and strip now carry the following colour codes for easy recognition of gauge in-store or on-site. Australian Standard AS2904-1986 "Damp-Proof Courses and Flashings" recommends 20kglm2 lead sheet for all exposed lead flashing. This gauge is necessary for flashings exposed to direct sunlight in a northerly or westerly aspect. However, in concealed locations, lighter 15kg/m2 sheet is often suitable. 10kg/m2 sheet is unsuitable in any exposed situations, as it does not have the stiffness to withstand thermal expansion and contraction without buckling. This gauge is also difficult to dress or leadburn. Another golden rule that helps to make the most of Quality Lead concerns length. Individual strips or pieces of lead should be limited in size. The thinner the lead the smaller the piece. Again this will minimise the effects of expansion and contraction. For long flashings, lead should be cut and overlapped to accommodate thermal movement - 20kg/m2 should not be installed in lengths longer than 1.5m. Where sheets broader than those used for flashing are being installed, they should not exceed 1.5m2 In area. 15kg/m2 is not recommended for external flashing. The presence of small amounts of certain other metals can modify the grain structure of lead, making the grains smaller and more uniform. This improves fatigue resistance and metal is better able to cope with stresses arising from thermal movement. The composition of soft lead sheet and strip used for flashings and weathering's is covered by Australian Standard AS1804-1976, and requires the addition of a small amount of copper. Copperised lead sheet is made by milling (rolling) a cast slab or by direct machine casting. The amount of copper added depends on which manufacturing method is used, but the small variation is insufficient to affect lead's characteristic softness and malleability. Most flashings are installed externally where they are subject to changing temperature. While all metals expand and contract in response to temperature changes, lead "moves" somewhat more than most. During summer, the temperature of metal on a roof can be up to 40 °C higher than ambient -and day-to- night variations can be as high as 60 °C. This is enough to cause a two metre length of lead to expand by more than 3mm. If expansion and contraction cannot occur fairly freely, there is a risk of lead lifting and buckling. Further expansion and contraction will then cause bending about the buckle until fatigue occurs. This is evident by jagged cracks which follow the boundaries of the metal "grains". Lead Dampcourse complies to Australian Standard AS2904:1995
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