Fire Rating and Fire Protection Design Requirements for Aluminum Veneer Curtain Wall

The fire performance of aluminum veneer curtain wall is a core component of building fire safety. Its design, construction and acceptance must strictly comply with the current national mandatory standards such as Code for Fire Protection Design of Buildings (GB 50016, aligned with the International Building Code (IBC)), Classification for Burning Performance of Building Materials and Products (GB 8624, aligned with ASTM E84), and Technical Code for Metal and Stone Curtain Wall Engineering (JGJ 133). A complete curtain wall fire protection system is constructed through material fire performance control and structural fire protection design to eliminate the risk of fire spread in the event of a fire.

Core Combustion Performance Classification of Aluminum Veneer Curtain Wall

1. Fire Rating of Base MaterialThe core base material of aluminum veneer curtain wall is aluminum alloy sheet, which is a non-combustible material. According to GB 8624 standard, its combustion performance grade is Class A non-combustible, with no combustion, no melting dripping, no toxic fume release, which fully meets the basic fire protection requirements of building exterior envelope structures. This is also the core fire protection advantage of aluminum veneer compared with exterior wall materials such as plastic, organic boards and wood boards.
2. Fire Protection Requirements for Coatings and Supporting MaterialsAlthough organic coatings such as PVDF fluorocarbon coating and powder coating on the surface of aluminum veneer are combustible components, the coating thickness is usually only 30-50μm, with a very low proportion, which will not affect the overall Class A non-combustible grade of aluminum veneer. For buildings with special fire protection requirements, fire-resistant fluorocarbon coating and inorganic ceramic coating can be used to further improve the fire performance of the coating.At the same time, the supporting sealant, thermal insulation materials, fire blocking materials, etc. of the curtain wall must meet the corresponding fire protection requirements: the building exterior wall thermal insulation materials must use Class A non-combustible or Class B1 flame-retardant materials according to the building height and type; fire-resistant sealant and fire blocking materials must use Class A non-combustible materials with nationally recognized test reports.

Core Fire Protection Design Requirements for Curtain Walls of Different Building Types

According to GB 50016, the fire protection design of aluminum veneer curtain wall must implement differentiated design standards according to the building height, use function and fire risk. The core requirements are as follows:

1. Fire Protection Design for Residential Building Curtain Walls
   • For multi-storey residential buildings with building height ≤27m, the exterior wall thermal insulation material shall not be lower than Class B2, and fire blocking must be done between the curtain wall floors;
   • For Type II high-rise residential buildings with 27m < building height ≤54m, the exterior wall thermal insulation material shall not be lower than Class B1, and a horizontal fire isolation belt must be set on each floor;
   • For Type I high-rise residential buildings with building height >54m, the exterior wall thermal insulation material must use Class A non-combustible material, and a continuous fire blocking structure must be set between the curtain wall floors.
2. Fire Protection Design for Public Building Curtain Walls
   • For single and multi-storey public buildings with building height ≤24m, the exterior wall thermal insulation material of crowded places must use Class A non-combustible material, and other places shall not be lower than Class B1;
   • For Type II high-rise public buildings with 24m < building height ≤50m, the exterior wall thermal insulation material shall not be lower than Class B1, with a horizontal fire isolation belt set on each floor;
   • For Type I high-rise public buildings and super high-rise buildings with building height >50m, the exterior wall thermal insulation material must use Class A non-combustible material, and the fire protection structure of the curtain wall must be specially designed and checked.
3. Fire Protection Design for Curtain Walls in Special PlacesFor crowded places such as hospitals, schools, shopping malls, stadiums, convention and exhibition centers, regardless of building height, the exterior wall thermal insulation material must use Class A non-combustible material. For curtain walls of industrial buildings such as factories and warehouses, the corresponding fire protection design standards must be implemented according to the fire risk category of production, and combustible and flammable materials are strictly prohibited.

Core Fire Protection Structure Design Points of Aluminum Veneer Curtain Wall

The fire safety of aluminum veneer curtain wall lies in inter-floor fire blocking and vertical fire separation, rather than only relying on the non-combustible performance of the panel itself. This is the core principle of curtain wall fire protection design.

1. Inter-floor Horizontal Fire Blocking DesignThe gap between the upper and lower floors of the building, and between the floor slab and the curtain wall must be continuously and densely blocked with Class A non-combustible materials such as fire-resistant rock wool and fire blocking boards. The blocking height shall not be less than 0.8m, and the fire resistance limit shall not be lower than that of the floor slab. The blocking structure must be supported by galvanized steel sheet, and combustible material support is strictly prohibited to ensure that the fire will not spread upward through the inter-floor gap in the event of a fire.
2. Fire Protection Design for Wall Between Windows and Window Sill WallWhen the height of the wall between windows and window sill wall corresponding to the curtain wall is insufficient, a fire-resistant glass wall with a fire resistance limit of no less than 1.00h must be set at the upper and lower edges of the window, or a solid fire partition wall with a height of no less than 0.8m must be set. For curtain walls without window sill walls, a fire canopy with a height of no less than 1.2m must be set at the outer edge of each floor slab, or a continuous horizontal fire isolation belt must be set to prevent the fire from spreading vertically through the gap between the window and the curtain wall.
3. Vertical Fire Separation DesignThe junction between the curtain wall and the fire wall and fire compartment of the main building must be densely blocked with Class A non-combustible materials to ensure the integrity of the fire compartment. The curtain walls on both sides of the fire partition wall and fire shutter in the building must be equipped with corresponding fire blocking structures simultaneously to avoid the horizontal spread of fire through the curtain wall cavity.
4. Special Design for Fire Protection NodesSpecial nodes such as internal and external corners, expansion joints, settlement joints, seismic joints, door and window openings, and parapet walls of the curtain wall must be specially designed for fire protection, using flexible fire blocking materials to ensure that the integrity of the fire blocking can still be maintained when the nodes are deformed or displaced. The electrical pipeline penetration of the curtain wall must be blocked with fire-resistant sealant to eliminate the fire spread channel.

Core Control Points for Fire Protection Acceptance

1. All fire-related materials must have factory qualification certificates, fire resistance limit test reports, and combustion performance classification test reports. Unqualified materials are strictly prohibited from being used;
2. The fire blocking structure must be continuous and dense, no gaps or omissions. The whole process image data must be retained during the construction of concealed works, and on-site verification must be carried out during acceptance;
3. The fire compartment, inter-floor blocking, and window sill wall design of the curtain wall must be consistent with the fire protection design drawings, and unauthorized design changes are strictly prohibited;
4. For the curtain wall fire protection system of super high-rise buildings and special places, special fire performance-based design and acceptance must be carried out to ensure compliance with fire safety requirements.