Lead is commonly is used as a means to complete and help maximise the efficiency of a roof's water sheddings qualities. It invariably can be found in a number of locations on a roof's profile and it's main function is to channel and deflect rainwater. For roof detail the gauge of lead to be used will be dependant upon the application.
Lead is used to make flashings, soakers and trays, for example, around chimneys and dormers; for sadles near ridge detail or for valley construction at a roof intersection where one pitch joins another. However, with some more extravegant property design, lead is used as the main waterpoof covering.
Although lead has properties that make it conducive for needs of roofing, as with any other material it does have a limited life-cycle. With the stesses and strains roofs have to endure, the lead element of a any roof covering can fail by spliting or in some instances can work free from its original fitting.
It takes a particular skill to be able to fashion, shape and install lead so that not only is it efficient and functional in it's primary purpose, but as to ensure that it adds to the property in an aesphetic sense also.