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Fire ratings explained

The level of fire classification required in glass block applications will always be a condition of building regulations or building control. The fire ratings required are wholly dependent on the location or area of use. Architect specification should ensure all aspects of the project are considered in line with approval.

Fire rated blocks can be used internally or externally. Common applications are areas such as fire escape routes, areas within apartment dwellings, corridors, where a private space is adjacent to a communal area, external boundary or perimeter walls, loft conversions or garages or in close proximity to other buildings or public highways.

There are two specific parts to a fire rating for glass blocks:

Fire integrity: is the length of time the wall will remain stable in a fire.

Thermal isolation: relates to the time it takes for significant heat to transfer from the side of the fire through the complete glass block. For the purpose of an escape corridor this is critically important in respect of heat coming into contact with people evacuating via the escape route.

Three fire ratings can be achieved:

  • F15 achieves 60-minute integrity and 15-minutes thermal isolation.
  • TF30 achieves 60-minute integrity and 30-minute thermal isolation.
  • TF60 achieves 60-minute integrity and 60-minute thermal isolation.

When a panel is tested for fire, not only the block is tested, but the complete system, encompassing the mortar, amount of reinforcement, joint dimension, perimeter expansion joint and fire-retardant sealant, forming the basis of how fire glass blocks should be specified and installed.

The maximum panel size permissible is 9m(in line with original test). The width or height must not exceed 6m in either direction.

Glass blocks MUST be constructed in accordance with the recommended installation instructions to comply and validate test certification.