The introduction of paid parking at businesses around the busy hospital precinct has meant its dedicated car park was often filled by 8am as drivers made the most of the free space.

"This impacts our patients and visitors who are unable to find parking on the campus," a spokeswoman said.

The private hospital will introduce fees next month at the carpark next month to deter other motorists and make sure there are enough spaces for visitors.

A sign that went up in the John James Medical Centre, which leases its space from the hospital, this week said visitors would have to pay $1 an hour for parking from the start of this month.

However, the Calvary spokeswoman confirmed parking was still free and the date in August fees would be introduced hadn't been decided on yet.

Discussions were also ongoing about how much visitors would be charged but she said staff were keen to keep it "affordable", she said.

The hospital is owned by the John James Memorial Foundation and is operated by Little Company of Mary Healthcare.

The foundation forecast it could introduce paid or timed parking to try to ease parking shortages at the busy Deakin site when it announced long-term plans for a facelift in 2013.

The master plan to expand the hospital and upgrade facilities will require hundreds of millions in capital works and could take from 15 to 20 years to complete redevelopment that will add 100 beds and new services.

The foundation unveiled a plan to expand the hospital and update the facilities that were built in the 1960s.