Some condominium buildings have masonry party walls between the units which extend some 2 feet or more above the roof. Other condominiums do not. I always thought these party walls were for fire separation. Why are they required in some buildings and not in others?
Fire-rated party walls are required to separate all condominium units. Recently, however, codes have permitted the use of fire-rated plywood in roof constructions. The party walls can now be built up tight to the bottom of this plywood, and since the plywood is fire-rated, a fire separation is established. The use of these materials, however, must be carefully evaluated to prevent long-term durability problems. Many of the salts used to treat wood for fire resistance are corrosive to metals.