We recently had our bathroom redone, when the shower tray was removed it had been sitting on the joists so the bathroom guy covered them with wood. Unfortunately we have a 3 inch by 15 inch bit that is lower than the rest of the wood floor, and it slopes from one end to the other (a gentle slope up the 15inches). We want to lay vinyl but need to fill in the dip; what would you recommend? A piece of wood would be tricky to fill in the slope with. Would wood filler work? Or would it have to be levelling compound (which I'd hate to have to do for such a small area)? Or is there something else I haven't thought of? Thanks.