We have put our 2x6s joists down in our bathroom that is 2.45m by 1.45m.
We realized that we are short by about 8cm, so we were thinking, is it a bad idea to put 2 by 6s flat I.e the 6 going horizontal, the 2 going vertical, perpendicular to how the joists are at the moment? Or is this not allowed? And if so, is there a required span?
Plywood and tiles will go on top of this as it’ll be a wetroom.
Please see the picture below.
Also, when I said 2x6s flat I mean like this.
Best Answer
I would say that the main issue with putting down boards like that is cupping or bowing of the wood especially since this is a high moisture area; that's dirt beneath the joists, right? Look at any wooden deck and you will quickly see what I mean by bowing or cupping.
Additionally if you haphazardly layout the boards like that then there will obviously be unsupported areas which will sag as soon as someone steps on it.
I recommend furring up the floor joists by using a table saw to rip 2 inch pieces of wood and attach them directly to the top of the joist.
If you don't have a table saw then you should be able to buy furring strips directly from a lumber yard or supply store.