A long-term ground-sharing arrangement will protect Perth's access to Lathlain Park when the ground is redeveloped into West Coast's headquarters over the next three years.
Under a deal agreed to by the Eagles, Perth and the Town of Victoria Park, both football clubs will have separate leases for new premises to be built at Lathlain Park from next year.
West Coast will also hold the lease to the playing fields - the existing oval and a new oval the size of the MCG to be built in the current eastern car park.
But Perth's use of the grounds will be guaranteed for the 20-year life of the agreement.
"We will each have separate areas under separate leases but share the ovals," Perth president Vince Pendal said.
"They will have the lease (on the oval) but under a joint agreement with us and the council on a ground-sharing basis.
"That has been agreed to and all we are waiting on is two new leases. Hopefully that will happen in the next couple of months."
Pendal also confirmed West Coast were compensating Perth for the loss of their naming-rights sponsor which brought the club about $30,000 a year.
The new football precinct is expected to bear a commercial name that will provide the two clubs with about $100,000 a year.
West Coast are seeking funding for a $60 million redevelopment that will replace the current Lathlain Park facilities with two new club houses, a grandstand and other spaces suitable for commercial and community use. Ground lighting will be upgraded to enable night matches to be played, and the Eagles will pay about $1 million towards Perth's new base.
West Coast intend to contribute about $20 million to the redevelopment, which would provide them with a new home only a few kilometres from the Burswood stadium which is scheduled to be in use for the 2018 season.
"The process is that their works will be done first and then we will move into their building and ours will be demolished," Pendal said.
"The idea is that it will be a two-year program in 2015 and 2016 and then they will move in for 2017.
"That's subject to the necessary funding and approvals.
"We are working towards a situation where we won't suffer any loss of our oval like Claremont have had to suffer."
The leases were to be signed by yesterday but have been delayed until the end of June because of the complexities of the deals.
"They have been deferred by mutual agreement," a West Coast spokesman said. "There is no risk to the development."