A council has agreed to find an extra £6.4m to redevelop a theatre after the estimated cost rose to £19.9m.
East Hertfordshire District Council agreed to invest the money in Hertford Theatre, on top of £13.5m previously allocated.
The existing building was found not to be strong enough for the proposed roof-top extension for three cinema screens.
The council said it was a "significant increase" but there would still be "a strong return on investment".
As well as the roof extension and an enhanced main auditorium, the plans include a 150-seat studio space with a balcony, community rooms, and a cafe over-looking the River Lea.
To accommodate the cinema, part of the building will have to be demolished and the new facilities built in its place, the Local Democracy Reporting Service said.
The council's loan from the government's Public Works Loan Board, will fully fund the scheme, and will be repaid over 30 years.
Conservative councillor, Eric Buckmaster, responsible for wellbeing, said that even with the additional investment, there would still be a positive return.
Currently the council subsidises the theatre by £311,799 a year.
After the revamp it is believed it will operate at a profit and contribute about £110,201 a year to the council, partly through offering "first-release" films.
Labour group leader Carolyn Redfern expressed concern over the level of borrowing, ticket price increases and extra costs for amateur and not-for-profit companies using the theatre.
Liberal Democrat Sophie Bell highlighted similar concerns, saying it was important that these groups were not "priced out" of using it.
Theatre manager Rhys Davies said the increased capacity could bring additional income for those companies, and they would also be able to use the smaller studio theatre for productions likely to attract a smaller audience.