I'm in the process of gutting/remodeling our small half bath due to a rotten subfloor. When I pulled out the vanity I discovered there was a false bottom in it with just a register vent screwed to the kickplate. The 5 inch round ductwork stops flush with my subfloor, I was just going to buy a boot and put a floor register in. My floor joists are 16 in. on center, and there is one right next to the duct, on the other side of the duct are two floor joists sistered together (I assume for supporting the house). This leaves me a distance of 8 inches between the two joists where the 5 inch duct comes up through the floor. I can't run new duct work because my furnace is in the way, if I use flexible duct work it will hang underneath the joists and if I ever finish my basement this will cause a problem. I also don't want to put a vent in the wall because I am planning on using travartine on the walls. Does anyone have any suggestions/fixes, I would greatly appreciate it! Thanks.