ISO 1 – Frame
Description: ISO 1 construction involves combustible materials in the walls and/or roof. This type typically includes wood frame walls, floors, and roof decking. Exterior finishes may consist of brick veneer, wood or hardiplank siding, and stucco cladding. The roof is typically wood-framed and can be covered with various materials such as shingles, clay/concrete tiles, built-up roofing (BUR), single-ply membrane, and occasionally metal sheathing.
Roof Anchorage: Roof anchorage methods can include toe nailing, clips, single wraps, and double wraps.
Examples: ISO 1 structures are often found in residential buildings, including single-family homes and low-rise apartment complexes, usually up to 3-4 stories.
ISO 2 – Joisted Masonry (JM)
Description: ISO 2 construction combines noncombustible masonry walls with a wood frame roof. The exterior walls are typically constructed using concrete block, masonry, or reinforced masonry. Exterior cladding options include stucco, brick veneer, painted concrete block, or Exterior Insulation and Finish System (EIFS). Floors in multi-story buildings can be wood-framed with wood decking or concrete on wood or steel deck. The roof is usually wood-framed with a variety of roof coverings.
Roof Anchorage: Similar to ISO 1, roof anchorage can include toe nailing, clips, single wraps, and double wraps.
Examples: ISO 2 structures are versatile and can be used for small office buildings, retail spaces, and residential buildings up to 3-4 stories.
ISO 3 – Non Combustible (NC)
Description: ISO 3 construction is characterized by non-combustible materials in the building’s construction. This type typically includes steel frame walls with masonry in-fill, metal sheathing, or EIFS for exterior finishes. Steel framing is a load-bearing part of the building frame, and various roof systems can be used, including built-up roofing (BUR), single-ply membrane, foam/spray applied roofing (typically over an existing roof), and metal roofing. Roof anchorage methods vary depending on the construction.
Roof Anchorage: Light steel frame ISO 3 may use clips, single wraps, or double wraps. Heavier ISO 3 construction typically requires engineered bolted and/or structural roof connections.
Examples: ISO 3 construction is often found in warehouses, manufacturing facilities, and similar structures.
ISO 4 – Masonry Non Combustible (MNC)
Description: ISO 4 construction combines concrete block, reinforced masonry, or tilt-up concrete load-bearing walls with some heavy steel framing. Floors are commonly concrete on steel deck for multi-story buildings. Roof construction options include steel deck with insulation boards, lightweight insulating concrete or gypsum board, and sometimes heavier concrete on steel deck if the exposed steel is not fireproofed to meet ISO 5 requirements. Various roof coverings are used, including BUR, single-ply membrane, and metal panels.
Roof Anchorage: Roof-to-wall anchorage typically involves engineered bolted and/or structural roof connections, as toe nailing, clips, single wraps, and double wraps are not applicable.
Examples: ISO 4 construction is often seen in shopping centers, strip malls, office buildings, and warehouses.
ISO 5 – Modified or Semi Fire Resistive (MFR or SFR)
Description: ISO 5 construction involves protected steel and/or concrete walls and floors, offering semi-fire resistance. Roof systems can include heavy steel framing with concrete poured on steel deck, precast concrete panels, or steel deck with insulation boards. Exposed steel must be fireproofed to meet required fire ratings.
Roof Anchorage: Roof-to-wall anchorage is typically achieved through engineered bolted and/or structural roof connections. Toe nailing, clips, single wraps, and double wraps are not used.
Examples: ISO 5 construction is commonly found in high and mid-rise office buildings and condominiums.
ISO 6 – Fire Resistive (FR)
Description: ISO 6 construction is characterized by reinforced concrete building frames and floors or well-protected steel and concrete components. Floors are typically made of minimum 4″ cast-in-place concrete, precast concrete, or concrete on protected steel. Roof systems may consist of cast-in-place reinforced concrete or precast concrete. Some cases involve structural concrete poured on steel deck, with exposed steel fireproofed to achieve a minimum 2-hour fire rating.
Roof Anchorage: Roof-to-wall anchorage is achieved through engineered bolted and/or structural roof connections, as toe nailing, clips, single wraps, and double wraps are not applicable.
Examples: ISO 6 construction is commonly seen in high-rise office buildings, condominiums, and parking garages.
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