Exeter Chiefs have been granted planning permission to
The ground's current capacity of 10,700 is the lowest of any of the 12 clubs in the Premiership.
It means the Chiefs cannot host matches in the latter stages of European tournaments as teams must have a minimum capacity of 20,000.
The club are set to raise funds for the project by selling preference shares in Exeter Rugby Group Ltd.
"We've been a few years working up the plans and all of this is commensurate with getting into the Premiership," chief executive Tony Rowe told BBC South West Sport.
Rowe will explain the share sale plans at a special general meeting of the club on Wednesday night, and the investment comes a month after the club
"We do have some private investors who are going to help us financially to get the project under way," Rowe added.
"We have great confidence that we're going to survive in the Premiership.
"If I look into my crystal ball I don't see any changes for a long time at Sandy Park and, if we all work together as we have done for the last 15 years or more, we'll achieve all our ambitions."