Adding joists to make new bulk head

[Richard Cull]

Hi I am building a bulk head over stairs in order to extend the box room. I have C16 2x4 to build a small supporting wall one side that will have rested ontop 2x4 joists which will connect across to joist hangers on the other wall (external brick) - joist distance about 900mm. I assume the joists secured on a 2x4 wall plate is fine? Like in photo.

I also plan on building a small partition wall above the bulk head which will I might make to take the weight of the end of a single bed (other sides will be bolted on external walls, which will take much of the load). So, there may be some load on this wall, although it will essentially sit ontop of the small supporting wall one sideand the wall plate on the other.

The wall on plate will be attached using several concrete M10 bolts.

Is a 2x4 wall plate enough? I am assuming so but best to check!

Thanks for your help, much appreciated.