I'm going to lay quite a large floor, about 70 m2. Since I'm laying an unplaned larch floor, I thought about placing chipboard between the floor joists and the larch for sealing. I've spaced the joists at 60 cm centers. Flooring chipboard is quite expensive compared to regular chipboard. Since the larch (1-1.25 inches) is supposed to be the actual load-bearing floor, would it work with slightly weaker board material in between?
For what reason do you want to "seal"? Because gaps in the floor shouldn't mean an open path down to the joists? Skimping and buying regular chipboard, sure it might work - and it probably will. Glue and screw the boards to avoid creaking etc. But for some reason, it still feels a bit half-hearted...