I am planning to remove a portion of a non-bearing wall that separates two rooms, one of which has a vaulted ceiling. I want the horizontal ceiling to continue all the way to the wall in the room with the vaulted ceiling, i.e. I want any required header to be in the ceiling. The span will be about 10 ft.
Although this wall is non-bearing, it does support the "knee wall" between the lower ceiling and the vaulted ceiling.
I was originally prepared to install a double 2x12 header across the span, with king and jack studs on either end. This would be sufficient for a load bearing wall with the same span, so I suspect this is more than required for a non-bearing wall.
One difficulty I'll have with a double 2x header is that this is a 2x3 wall and there is a ceiling joist right against the wall. So in order to double up 2xs, I'd need to shave ~1/2" off of the thickness of one of the boards.
The ceiling joists are 2x6s and are not engineered truss components.
My current plan is to trim the bottoms of the 2x3 studs in the knee wall (above the point where the plaster is removed in the photo below), install a 2x6 + plywood header (single 2x6 sandwiched in plywood to match the thickness of the 2x3 wall), and add king/jack studs at either end.
Is this reasonable?