Is there a legal height requirement for a fire door? We're converting half of a double garage into a habitable room. There is a dividing wall down the middle of the garage with an existing door way (no door or door casing/frame). Because we have installed a floating floor we now need to take 5" off the height of the door. The alternative would be to make the door way bigger and fitting a new lintel but i'd rather not if there is no obligation to do so.