Openings
Similar to fire doors, the location of the opening, required class of fire protection, and size dictate the type of fire-rated glazing suitable for use.
Fire-protective glass is available with up to 90-minute fire ratings for use in openings and windows where protection against heat transfer is not required by code. The limitation on heat transfer makes it important to verify the product satisfies both the application’s required fire rating and type of fire protection. For example, many codes require fire-rated glass in one-hour egress applications to slow the spread of flames, smoke, and heat. While fire-protective glass is available with the necessary 60-minute fire rating, it is unable to protect against the transmission of heat. As such, it is typically unsuitable for such applications.
Walls
Fire-resistive glass and frames can be used in applications where building codes require a fire-resistant wall with no ‘openings’ to enclose a space. Fire-protective glazing does not defend against heat transfer, and is therefore not suitable for such applications as it is considered an ‘opening’ protective. Fire-resistant walls can include, but are not limited to:
- stairwell enclosures;
- fire-rated curtain walls;
- exit access corridors; or
- other fire barriers dividing interior construction (so-called ‘building compartmentation’).
Since fire-rated walls allow for great variance in design, the following are some key factors to consider before selecting a product:
- generally, only fire-resistive glass and frames may be used in wall applications requiring a 60-minute or greater fire rating;
- fire-resistive glazing may exceed 25 per cent of the total wall area;
- the entire assembly, including the glass and frames, must be rated equal to (or greater than) the wall; and
- like the fire-resistive glazing, the intended frame system must also block radiant heat transfer during a fire.
Assuming these criteria are met, the flexibility to use fire-resistive glazing in various configurations in walls provides building teams with many benefits, from improved daylight transmission to enhanced occupant visibility. For example, project teams can incorporate expansive sequences of fire-rated glass wall panels throughout school corridors, where illumination and views to the outside can help create a quality learning environment. Or, they can install fire-rated curtain walls in stairwells to help create safer walkways and brighten hard-to-light interior cores.
In addition to light transfer, clear fire-rated glass and narrow fire-rated frames make it easier to maintain visual consistency between fire-rated and non-fire-rated materials. This is particularly valuable when using large sequences of fire-rated wall panels or expansive fire-rated curtain walls. Frames can be custom painted or powder coated to match virtually any colour scheme. Framing options also include aluminum and steel. A recent innovation in framing makes it possible for fire-rated applications to be free of front framing members, mirroring the sleek look of structurally silicone glazed (SSG) systems.
Floors
Advanced fire-rated glass floor systems incorporating fire-resistive glazing are available for interior and exterior applications that require a code-approved fire barrier between floors. Common applications include:
- lobby floors;
- atriums;
- corridors near exits; and
- other public egress areas at risk for fire progression.
Currently, glass floor systems that pass fire-resistance tests are available with fire ratings up to 120 minutes. Non-egress floor or roof applications typically require 60- to 90-minute fire ratings; public egress areas typically require 120-minute fire ratings.
Beyond fire protection, interior and exterior fire-rated glass floor systems are available approved for loads up to 732.4 kgf/m2 (150 psf). This is typically suitable for commercial and high-traffic pedestrian uses, as well as for public gathering areas like airports and railway stations.
To account for a broad range of installation circumstances, manufacturers or suppliers typically offer various surface treatments to improve traction. Embossed glass or cast glass features a slightly uneven surface texture that has good non-slip characteristics and long-term durability. Ceramic frit texturing is another traction-providing option. Its sandpaper-like surface is non-slip, although it is susceptible to wear in high-traffic installations.
The building envelope
Fire-resistive glazing can be used in exterior applications to help prevent a fire from spreading to or from other nearby buildings. This is becoming increasingly relevant in areas with high building density and narrow setbacks from lot lines. Refer to local building codes for horizontal separation distances requiring fire ratings for building exteriors. Generally, the allowable opening area correlates to the distance between the two buildings.
