Well between a Big Brother and Celeb Big Brother the house is sometimes rented out for events, then it's stripped down a bit and given a bit of a make over. The studio is probably moved into storage for others to use the space unless Big brother actually owns it instead of renting out the space.
Between a Celeb series and Main series the house and studios are ripped apart to the shell and unlike most international versions a whole new shaped house plan is drawn up and ready to be built.
(House between CBB5 - BB8)