Ah, flooring and which way it should run!
I work on the principle that the floor boards run opposite to the joists, which I conceptualise from the roof downwards.
Thus, assuming a two storey square building of brick built construction:
(If) Roof slopes front to back
Roof joists run front to back
Mid-level joists run left to right
Ground-level joists run front to back.
So, in the above, the flooring would be:
Upstairs boards run front to back
Downstairs boards run left to right
Unless, I've got myself tied up in knots, this should enable the structure to cope with the weight of the roof bearing down on the walls, as the roof pushes the front and rear walls outwards but they are pulled back in (tied in) at the mid-point, thus discouraging bowing of the brickwork.
I will now take a bow for the chorus of "pedant!"

PS: Not to be used as the basis for building a real house!
