LONDON - Restoration work to Britain’s houses of parliament could cost as much as 5.7 billion pounds ($9 billion) and take 32 years unless lawmakers are moved out of the building, according to a report published on Thursday.

The Palace of Westminster was rebuilt on on the banks of the River Thames in the mid-1800s following a fire. Many of its features have never undergone major renovation since. The independent report, commissioned by parliament’s lower and upper houses, found asbestos throughout the building, stonework crumbling, roofs leaking and plumbing failing. “Parliament is faced with some difficult choices. The Palace of Westminster is a building of huge national and international importance and we face a massive challenge in securing its future,” said restoration programme director Richard Ware. A world heritage site, the palace incorporates the tower of Big Ben and other outstanding examples of 19th century neo-gothic Victorian architecture.

The oldest building on the site, Westminster Hall, dates from 1099 and is still in daily use.

The report, commissioned in 2013 after a study found the buildings to be at risk of major, irreversible damage, set out five options for the restoration work.

These range from a six-year programme costing 3.5 billion pounds which would require lawmakers to completely move out while the work was done, to a 32-year rolling programme carried out while the building continued to function as a parliament, at a cost of 5.7 billion pounds. Members of both the lower and upper houses will now decide which option to pursue. Work is not expected to start before 2020.