It is expressly provided that Sections 59-23-10 and 59-23-20 shall apply to school buildings in use on March 18, 1924, to buildings the plans, specifications or descriptions for which had been drawn prior to that date and to buildings actually in process of construction on that date, but no such building shall be affected by the building code set forth in Sections 59-23-40 to 59-23-190.