i am installing a bathtub that does not fit exactly into the alcove. i understand that this is probably a normal occurence but i am unsure what to do. to be more specific, the fit is against studs not drywall and i plan on doing a tile surround. the bathtub is 1/4" to 1/2" too short for the alcove. i was thinking of putting a 1/4" sheet of plywood in as spacer. this plywood sheet would be tall enough to not only take up the space at the tub but also the surround. of course, now i have a spacing issue with the remaing drywall. suggestions please.