Alterations. When any existing building or structure accommodates a legal occupancy and use but is of a substandard type of construction, then alterations which involve beams, girders, columns, bearing or other walls, room arrangement, heating and air-conditioning systems, light and ventilation, or changes in location of exit stairways or exits, or any or all of the above, may be made in order to bring such existing construction into conformity with the minimum requirements of this chapter applicable to such occupancy and use and given type of construction, when not in conflict with any other regulations.