London Borough of Croydon has increased its cost estimates for a regeneration scheme.
The council confirmed in a response to a Freedom of Information request that the costs to redevelop Fairfield Halls has escalated from £30m to £41m.
The overhaul of the 1960s arts, conference and theatre complex is part of a plan to create a cultural quarter in the town to rival central London.
The venue now needs additional fire protection, a new back-of-house and additional work to meet industry standards.
The council advised: “Croydon Council is not a party to the construction contract for the refurbishment of Fairfield Halls which exists between Brick by Brick Croydon Ltd and Vinci Construction.”
