I have your soft wood tiles in my gym and I'm having issues with tile expansion because there is heavy equipment on both sides negating the expansion gap. Can we use polyurethane or other floor adhesive to hold the tiles down?

You can use a pressure sensitive or polyurethane adhesive to hold our 3/8" Soft Wood Tiles down. If you use an adhesive, the tiles would become damaged when removed. You can also use double sided tape which will allow you to move the tiles if need be.