I am going to install a 25 sqm solid pine floor and from what I have read, you should leave a 2cm gap all around. But the floor can't possibly move 2cm? The screws you use will stay in place and if the board moved 2cm, it would have split long ago.
3-4mm seems more reasonable
3-4mm seems more reasonable
I installed one of those in our cottage which is completely unheated in Sörmland during the winters. I left about 8-10 mm around it. However, I have fairly thick allmoge skirting boards at 21x120 mm, so no problem to cover up after I used lindrev.
2cm might apply if the floor is laid floating. If each board is screwed down, not much more movement joint is needed than what each board expands/contracts with the seasons. A little margin is never wrong though, but it should be possible to cover it with the skirting board.