One of Norfolk's 'hidden' heritage gems has been hit by subsidence, at a time when museum bosses are already spending almost half a million pounds on the building.

The subsidence at The Shirehall - which served as the city's court for more than 180 years - was uncovered during work to tackle dry rot in the Victorian, Grade II-listed structure.

Norwich Evening News: The Shirehall in NorwichThe Shirehall in Norwich (Image: Newsquest)

Further investigations are being carried out to assess what needs to be done to tackle the problem and to establish how much it would add to the rising bill of work at the building.

Norwich Evening News: The courtroom in the Shirehall was restored in 2013 (Image: Archant)The courtroom in the Shirehall was restored in 2013 (Image: Archant) (Image: Archant)

The subsidence problem is believed to be linked to the way the courtroom at The Shirehall was constructed in the 19th century.

It is likely that when it was built, a slice of the Castle Mound was cut away to provide the necessary space, with that ground proving to be unstable.

The need to tackle dry rot at the Market Avenue building was first identified in 2019, but did not begin until September last year.

When the dry rot problem was first identified, it was thought to affect a relatively small area of the wood-panelled Victorian courtroom.

But subsequent studies revealed it was a "significant" outbreak covering about 25pc of courtroom space and it will cost close to £500,000 to address.

The need to tackle the subsidence problem - along with issues with water getting into the building - will add more to the costs.

Norwich Evening News: Stuart Garner, Norfolk County Council's Norwich museums operations managerStuart Garner, Norfolk County Council's Norwich museums operations manager (Image: Archant)

Stuart Garner, Norfolk County Council's Norwich museums operations manager, said: "The works to the courtroom are progressing and are currently sitting at a projected cost of just over £493,000.

"We are hoping that these works will be completed by the end of the year, though this depends on how long the drying out period takes.

"Regarding the wider Shirehall works, the work still needs to be surveyed and costed by Norfolk County Council corporate property team.

"Until this has been carried out, we won’t know the extent of the work and associated costs."

Conservative-controlled Norfolk County Council recently agreed £42m of cuts and savings to balance its budget.

While the council had budgeted up to £580,000 for the dry rot work, Mr Garner said further sources of funding would need to be explored to pay for the wider works needed.

READ MORE: How Norwich Castle keep is being transformed in major revamp

HISTORY OF THE SHIREHALL

The Shirehall was built in 1822-24 as the county courtrooms for Norfolk and is attributed to architect William Wilkins.

The building is constructed in a neo-Tudor style and is two storeys tall, with red brick and limestone dressings.

Major structural work was carried out in 1846 and the building was refaced in 1913-14.

The Shirehall Chambers were built to provide extra offices in 1907.

The Shirehall was listed as Grade II in 1972.

Norwich Evening News: How the courtroom looked when it closed in 1988How the courtroom looked when it closed in 1988 (Image: Archant)

It ceased to be used as a court in 1988. The courtroom was then restored in 2013 and in recent years it has been used for 'living history' performances, as well as for public and private events.