Urgent repairs are to be made to the roof of Chichester Cathedral with £5.8million needed to replace its leaky copper covering with lead.
Permission was granted this week, with the full support of heritage bodies for the work, which will see the now green roof installed in the 1940s removed to assess the state of the medieval roof timber at risk of rotting underneath.
A historically accurate lead covering will be installed in place of the older cladding, while the cathedral is shielded under a temporary roof.
A cathedral spokesperson said the work could not be delayed without risk of further damage.
She said: “The scale of the project is enormous and unprecedented for the cathedral, which receives no statutory funding, relying wholly on donations and self-generated income for its restoration needs.
“This major undertaking has been estimated at a cost of £5.8million, and cannot be delayed without risk of further damage and increasing costs.
“The cathedral has been awarded a £250,000 grant from the First World War Cathedrals Repair Fund towards the initial phase of the work.
“The work on the choir (central) roof is expected to start later in the year, with a major fundraising campaign to be embarked on soon.
“These repairs and restoration will give the best protection to Chichester Cathedral for generations to come.”
According to a specialist report in the planning documents, the peregrine falcons that nest at the cathedral should adapt to the works as they happen.
A leaky area on the choir roof is most in need of attention, although it is thought there may be wider damage from timber-eating deathwatch beetles.
Work on the choir roof is set to start in November as scaffolding begins.
A temporary roof should be in place by Christmas and the main part of the work started in January 2018.