We are building a floor on the loggia. The workers put 50*50 wooden beams on the concrete base and 18mm OSB boards on it and fixed them with self-tapping screws. The boards were rammed into the walls, of course the walls are not flat and there are gaps, but there are places where the boards lie against each other. I think the expansion joints are necessary, but the workers say they are not. I need your advice – should I leave it as is or redo it?
Leave a gap of 1 cm covered by the skirting board.
OSB boards have a linear expansion of 0.15% at 70% humidity, so a gap is needed on the short side and 1-1.5 mm on the long side makes no sense.