ᐅ Install tongue-and-groove boards in the attic

Hello everyone!

We have decided to install the tongue-and-groove boards on our attic floor ourselves. Our joists are spaced 78cm (31 inches) from center to center.

Now I am wondering... Do the boards need to meet end-to-end directly on a joist? Or does it not matter if I stagger the boards randomly, with the ends overlapping 30cm (12 inches) beyond the joists?

I plan to use 23mm or 27mm (about 1 inch) thick tongue-and-groove boards.

How have you handled this?

Well, if you only want it as a subfloor to store things on, then a random pattern will be sufficient. If you plan to lay laminate flooring or similar on top and use the space as a living area, I would recommend aligning it over the joists.

It will be a dedicated storage room where the heating system with a 300-liter (79-gallon) hot water tank will also be located. This will, of course, rest on two beams.

I’m not sure if the laying pattern affects the stability?!

Nothing complicated. Always make sure the boards end on cross beams.

Boards should always be laid across the joists. Otherwise, simply walking on them can be uncomfortable if they "give way" or flex.

In an irregular pattern, ideally, you would have a cantilever of 39cm (15 inches); this not only wobbles but may give way under stress. Always make sure to bear on the beam! For the spans, it's better to use the thicker floorboard.