The writer-director told Empire that he is slowly adding to the screenplay when he meets up with his older sibling.
Raimi said: "We've got nine pages so far. Every time I'm with my brother Ivan, we write another page of it. It's in Detroit and in my garage.
"There's some dialogue. Ash being an idiot. Ash taking some abuse. Some character stuff and then some structure of Act Two.
"Just other possibilities for things that could happen. It's ideas, jokes, things we'd like to see."
He added that he wanted Bruce Campbell to reprise his lead role from the previous three movies, despite the actor's mixed statements on the prospect.