Attaching cross member to joists

[600rob]

Hi.

I want to fit a timber across two joists in the floor order to provide something solid to bolt down a wall hung toilet frame. (not confident in the chipboard floor boards)
Also do the same in the ceiling joists so i can build out a frame

Whats the best thing to fit the timber and ensure that its a solid fit?

Was thinking thick angle brackets.
Anything else more suitable that i can use?
Thanks

 

[foxhole]

Floor takes no weight, hence wall hung frame.

 

[600rob]

Floor takes no weight, hence wall hung frame.

My wall is a paramount wall with only a
couple of thin studs which i dont think is sufficient. The plan was to make an additional timber frame that ties into the floor and ceiling joists somehow then mount the toilet frame to that.
I suppose I could skip the floor section but will need to tie something into the ceiling joists