If you want your attic space to have a flat ceiling you ll need to add collar ties to the framing.
Framing out an attic.
Framing out an attic question.
Stand the front wall and align it with the marks on the floor.
Shim under the bottom plate to level it if necessary then nail it into the floor joists with 16d nails.
Run the plywood down to the top of the knee wall.
The plywood will create a smooth strong ceiling without having to apply drywall tape and mud to the ceiling.
This is the full view of the attic.
Install the lower header with joist hangers figure a and assemble the front wall on the attic floor.
Collar ties are horizontal members that like rafter ties extend from rafter to rafter but.