The critical importance of fire containment in high-rise buildings 

Fire safety in high-rise buildings is a critical concern, particularly in dense urban environments like Hong Kong. The vertical spread of fire and smoke through gaps between floor slabs and exterior curtain walls presents a significant risk to occupant safety and property protection. Effective passive fire protection, especially through properly designed and installed firestop systems, is essential to maintain compartmentation and comply with Hong Kong’s stringent fire safety regulations.

Traditional fire-fighting methods may often be powerless to help. Fire department ladders and hoses may not reach the source of a fire at higher levels. This makes effective fire, smoke and toxic gas protection and containment critically important: high-rise buildings need to cope with much longer fire exposure times. In particular, a strict compartmentation plan is crucial to create escape routes, help save lives, limit damage and comply with legal requirements.  

Role of Passive Firestop Systems in Curtain Wall Applications

Curtain walls create perimeter voids at the intersection with fire-rated floor slabs. These voids, if unsealed, may allow fire and smoke to spread vertically, undermining compartmentation. Passive firestop systems are designed to seal these joints and maintain the fire-resistance rating of the floor assembly.

Hong Kong Regulatory Context

Hong Kong’s fire safety regulations mandate that firestop systems:

• Comply with recognized fire test standards accepted by the Hong Kong Fire Services Department (e.g. BS476, EN 1366-4).
• Maintain fire-resistance ratings consistent with the building’s fire compartmentation strategy.
• Accommodate building movements and environmental conditions.
• Be installed by qualified personnel according to approved methods.
• Be regularly inspected and maintained to ensure ongoing performance.

Product approval may be required for certain fire protection equipment and test reports must be issued by recognized laboratories.

Curtain wall design should limit fire and smoke spread via interior joints 

The narrow gap between the floor slab and a building’s façade is bigger than it looks! 

Take a 100 x 100 ft. building with the usual 3” void. That may seem like a tiny footprint, but it adds up to 100 ft2 of open space for gas, smoke and flames to rise from floor to floor. The more floors a building has, the more critical this void becomes – it may allow fire to engulf the entire structure. After many fires that have taken hold via the voids between a fire-rated floor and non-fire rated curtain wall, architects and engineers now recognize how critical perimeter fire barriers are to high-rise building’s safety plan. 

Hilti CFS-SP WB Firestop Joint Spray

Hilti CFS-SP WB is a water-based, acrylic firestop joint spray developed to assist in fire containment at curtain wall perimeter joints. It has high-performance movement capabilities that meet leading industry test standards and can easily be painted. 

Stay on the safe side and contact us today!  

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