Complex sentence: Originally, the structure had 14 rooms on a single floor; an 1872 remodel added the second floor, using a different brick, and a verandah on three sides of the ground floor.
Split into simpler sentences: Originally, the structure had 14 rooms on a single floor. An 1872 remodel, using a different brick, added both the second level and a verandah on three sides of the ground floor.