Major refurbishment work has begun on one of Chester’s most important historic buildings.
Structural engineers and archaeologists have dug trial pits to investigate the cause of subsidence affecting the massive sandstone propylaea (gateway) at Chester Castle.
Designed by Chester–based architect Thomas Harrison, the listed Grade I entrance to the Castle is considered to be one of the best examples of Greek revival architecture in the country.
But recent subsidence has caused problems to the roof of this much photographed structure, causing serious water ingress.
Director of growth and prosperity Charlie Seward said: “We believe that the cause of the subsidence is linked to the structure’s 18th century foundations and possibly the modern installation of electric cable ducting supplying power to the castle.
“At present, in conjunction with English Heritage, we are considering the most suitable form of underpinning to prevent further subsidence and deterioration.”
Scheduled Monument Permission is needed for the excavations on both sides of the propylaea, which was finished in 1815 to complete the rebuilding of the outer-ward of the medieval castle.
Mr Seward added: “Council archaeologists will be monitoring this extremely important project which is part of the council’s commitment to preserve the historic buildings within its care.
“Quite obviously, on a scheduled monument site, there is the possibility that the excavations could provide interesting information for our archaeologists. Although it is very early days yet, I understand they have revealed part of the original parade ground and some medieval content.”
“Whilst the subsidence must be arrested, it is important to stress that the building is not in imminent danger.”
As part of the Listed Building Consent application, CWAC commissioned two local companies, Ramboll Uk Ltd & Russell Geomatics Ltd, to prepare a schedule of works.
A laser scan of the structure has already been carried out and these digital images will be used to monitor any further deterioration or movement.
Other much needed refurbishment of the propylaea will include:- waterproofing of the roof structure; repairs to stonework and mortar joints; cleaning of the stonework; improvements to the current rainwater drainage system; existing lighting replaced with more elegant and energy efficient fittings and removal of redundant cabling.
CCTV will be installed to deter misuse of the area; gates and railings cleaned and repair and repainting; minor repairs will be carried out to the stone-wall boundary of the Castle’s Parade Ground and new tarmac laid around the Propylaeum structure.