revision preference src: Exterior staircases leading up to second, third, or even fourth-storey apartments are common in many neighbourhoods, in part because historically this reduced the size of buildings and therefore decreased the owner's property taxes. <SEP> tgt: Exterior staircases leading up to second, third, or even fourth-storey apartments are common in many neighbourhoods, in part. Historically this reduced the size of buildings and therefore decreased the owner's property taxes.