Lay tongue and groove boards in the attic

Hello everyone!

We are going to lay the tongue and groove boards in our attic ourselves after all. We have a beam spacing (center to center) of 78cm. My question now is... Do the boards have to meet on a beam at the end? Or does it not matter if I lay them in a random pattern so that the ends meet 30cm outside the beam? I want to use 23mm or 27mm tongue and groove boards. How have you handled this?

Well, if you only want it as a floor to store something on, then a random pattern will be sufficient. If you want to lay laminate, etc. on it and "live" there, I would have it run together on the beam...

It will be a simple storage room, where the heating system with a 300l DHW tank will also be located. This will of course rest on 2 beams.

I don't know if the laying pattern has any effect on the stability?!

Nothing wild. Always let the boards end on cross beams.

Boards always on crossbeams. Otherwise, it is uncomfortable just to walk over it when it "wobbles".

With a wild pattern, ideally, you would have 39cm cantilevered; that not only "wobbles," it will give way if in doubt. Always butt against the beam! For the spans, better use the thicker plank as well.