Properties of Lead Sheet
Physical and Mechanical Properties of Lead Sheet
Malleability – Lead is soft, malleable and capable of being manipulated with hand tools and, by the technique of bossing, can be worked into the most complicated of shapes or dressed to fit the many types of profiled roofing tiles.
Fatigue and Creep Resistance – Attention to correct sizing and fixing of individual pieces minimizes any risk of fatigue cracking or creep. The chemical composition of rolled lead sheet is strictly governed by the provisions of BSEN 12588: which effectively control the grain structure to make the lead sheet more resistant to thermal fatigue without affecting malleability.
Durability and Thickness – When specified and fitted correctly, rolled lead sheet can continue to provide a maintenance free weather shield for 100 years. Rolled lead sheet is therefore extremely resistant to atmospheric corrosion. The ideal thickness and size of each piece is determined by the application. Thicker sheets may be required :
- when dressing lead into deeply profiled tiles
- in areas of frequent foot traffic
- on flat roofs and gutters
- where extra rigidity is required to resist wind uplift
Thermal Movement – Lead sheet has a high coefficient of linear expansion and therefore due allowance for thermal movement must be made in the design, layout, sizing of panels and fixing details to maximize performance.
Fire Resistance – Lead is incombustible but melts at 327.4°C.
Recyclability – Rolled lead sheet is totally recyclable. Scrap material is recovered from end of life buildings in the UK by a national network of reclamation merchants and channeled back to the manufacturers where it is carefully refined back to new feedstock for the rolling mills. The established recovery network, constant recycling of old material and low melting point with resultant energy efficiencies in manufacturing means the lead sheet industry has a solid reputation for environmental awareness and as a conserver of natural and energy resources, making it an environmentally friendly material.