The Craven Cottage boss has revealed the size of the rebuilding job he believes needs to be done to move the club forward after two years of treading water.
Jol is keen to avoid a repeat of this season's struggle for survival and already has one eye on the summer transfer market.
The Dutchman, by going public with his thoughts, has cranked up the pressure on the club's chairman and chief executive to back him with the funds to strengthen his squad.
Jol is still smarting from the loss of Moussa Dembele and Clint Dempsey to Tottenham on transfer deadline day last August, particularly as it looked like the club had fought off Liverpool's interest in the American.
"We need four, five or six players but that's normal at any club," said Jol. "We need to strengthen.
"Our home form was always good last year. Last year we could score out of nothing; we had Clint Dempsey to score winners. With Dimitar Berbatov, we gained somebody who could score goals but we lost things in other areas."