The Mill at Sonning is seeking planning permission to turn a rehearsal space into flats.
The development is part of the theatre's post-pandemic recovery strategy. The income from rent would be crucial to the business' survival, Managing and Artistic Director Sally Hughes said.
"This will enable us to preserve the heritage of the buildings and ensure they are refurbished and well looked after, while at the same time using the money to help us through tough times."
The Mill first got permission for the development years ago but rare bats were discovered in the roof and the permission expired before the theatre could begin works.
If the development is approved, staff and performers will have to find alternative rehearsal space and accommodation - the building is currently providing overnight stays.