It’s easy to see why clear and wireless fire-rated glazing materials have become a product of choice in door assemblies where glazing is necessary or desired and where fire and life safety is a concern. Their sleek look provides the aesthetic appeal of ordinary window glass while their unique product make-ups help protect against fires. Today’s sophisticated fire-rated glass and framing products have even made it possible for design teams to tailor fire-rated glass door and storefront assemblies to specific project goals. While this freedom is advancing design in code-driven areas, it can also increase the risk of misspecification. Since incorrect use of fire-rated glazing materials can cause more damage than good, the following fire-rated glass door dos and don’ts are designed to help guide proper selection.
The most critical step in the specification process is to ensure the fire-rated glazing materials provide the proper defense against the spread of fire. There are two material classes—fire-protective glazing and fire-resistive glazing. As described in the previous article, “The Evolution of Fire-Rated Glass Doors,” fire-protective glazing safeguards against the spread of flames and smoke. Fire-resistive glazing provides further protection by serving as a barrier to radiant and conductive heat transfer.
Specifying glazing materials with the correct level of defense is crucial since fire-rated glazing that provides protection other than intended could jeopardize the safety of building occupants. Consider doors in egress areas such as stair enclosures, which people must pass by or through to exit a building. If the assembly does not provide the necessary defense against heat transfer and temperatures reach high levels on the non-fire side of the door, the exit stair may be impassable.
As of the 2006 International Building Code (IBC), all fire-rated glazing in hazardous locations must pass the same impact safety test as non-rated glazing. This includes all fire-rated glass in doors. It also typically applies to fire-rated glazing adjacent to or near the door, including sidelites or glass located near the floor.
Since not all products provide both fire- and impact-safety protection, it is important to verify the selected offering meets either CPSC 16CFR (Category I) or CPSC 16CFR 1201 (Category II) impact classifications, as determined by the application. Today, numerous products meet this criteria and also have the capability to provide supplemental security protection, such as bullet and hurricane resistance.
When traditional wired glass was the only glazing material offering fire protection, little thought was given to light transfer in fire-rated glass doors. In large part, this was because codes limited fire-rated glass to small vision lites in doors with strict fire-rated criteria.
Now that fire-rated glazing is available in larger sizes and able to meet temperature-rise criteria, fire-rated glass doors, transoms and sidelites can serve as a daylighting asset and improve visibility between spaces. In fact, if a full-lite, fire-rated glass door is desired by the architect or building owner to enhance light transfer, a code-approved, fire-rated glazing solution is almost always available.
In fire doors with a 20- or 45-minute rating, fire-protective glass can often be used in the maximum size (as tested/listed by an independent testing agency). In doors with temperature-rise criteria, fire-resistive glass is an alternative. Since it is tested to ASTM E119, the standard for fire walls, it is suitable for use in all doors, without any size limitations beyond what has been tested and certified/listed by the manufacturer. When installed with matched sidelites and transoms, or as part of an overall fire-rated curtain wall assembly, it can allow great amounts of light to transfer between spaces with stringent fire- and life-safety criteria.
Although the design team is responsible for the initial product selection, it’s still crucial to take time to evaluate whether the product provides the appropriate level of protection and meets all required fire tests. This includes verifying that products with a rating greater than 20 minutes have passed the hose stream test.
Additionally, it’s important to see if the product has any special requirements, limitations or exclusions that may impact the building’s safety. For example, fire-rated glazing may provide the necessary fire rating, but only protect against fire from one side of the glass. This has the potential to compromise the life safety of building occupants if a fire starts on the non-protected side of the glass.
Fire-rated glass is just one piece of the fire- and life-safety protection puzzle. To work effectively, fire-rated glass must be installed into the appropriately rated door and lite kit, surrounding frame, and fire-rated door hardware for the required protection level. For example, specifying a 90-minute fire door with glazing listed for 20 minutes may be a mismatch for the required protection level of the assembly. To this end, the IBC requires all components to have the same or greater ratings and level of fire protection than the required code minimums for the opening.
It was once a foregone conclusion that the wraparound profiles present in many traditional fire-rated doors and frames would conflict with nearby non-rated door, window and curtain wall systems. Today’s slender offerings can sideline this challenge. For example, fire-rated steel door and framing systems incorporating precise European engineering can closely match the shape of aluminum profiles. Their narrow, extruded profiles better resemble the look of non-rated door systems, and are ideal for highly visible locations.
Where necessary, design teams can specify fire-rated frames in a wide array of colors, materials, and finishes, from authentic hardwood to stainless steel and bright hues. This flexibly helps prevent scenarios in which fire-rated doors and frames provide the necessary fire protection, but the frame color and material conflict with surrounding assemblies.
When it comes to fire- and life-safety protection in buildings, it’s important to specify and install proper products. If doubts arise during the design or specification process, manufacturers or suppliers can often provide valuable insights.
As originally published in the June 2018 edition of Understanding New Generation Fire-rated Glass Doors, a supplement of Door Security + Safety, sponsored by TGP. View the full supplement here.