Beneath the Cathedral's existing copper roof, much of the 13th century medieval timber structure survives for the entire length of the Cathedral. This timber structure has been described as 'among the least spoiled and most important roofs in the kingdom' (Cecil A. Hewett, English Historic Carpentry, 1997), making the Cathedral's medieval roofs of exceptional and national importance.
After the fall of the Spire, diagonal tie timbers were put in place to prevent the roof from collapsing. These later tie timbers, together with the diagonal boarding used to reinforce the roof structure whilst the spire was being rebuilt, remain in place. They are an important aspect of the story of the Cathedral and will be preserved.
Copper was used to re-cover the roof after WW2 when the traditional material, lead, was in short supply. Before this, and until the late 1940s, lead was always the material of choice, appearing in many historic photographs and engravings of the Cathedral.
Unfortunately, the technical limits of copper on very exposed high roofs were not fully appreciated at the time, and the copper was a cause for concern within a decade of its installation. In the early 1960s the Cathedral's Surveyor reported that 'in some vulnerable positions, the copper sheeting had torn its fixings, which will permit wind-whip and fatigue of the metal'.
Consequently, this much needed project will reinstate the historically authentic lead roof. Lead has consistently been used on the prestigious royal and religious buildings because of its longevity and appearance. For centuries eminent architects have praised its qualities; in 1708, Christopher Wren wrote: 'Lead is certainly the best covering, and lasting for many hundreds of years, is without question the most preferable.'
Lead will bring a longevity that far surpasses copper and, once completed, the Cathedral's roof will return the Cathedral to how it used to look before WW2.