A fire rated mortise lock is a mortise lock that has been tested and certified to maintain a fire door's integrity for a specified period during a fire event, typically ranging from 3 to over 4 hours depending on the certification standard. These locks are essential components of fire door assemblies in commercial buildings, ensuring that door hardware doesn't compromise the fire-resistance rating of the door itself. For architects and contractors specifying hardware on commercial projects, understanding fire rating requirements is critical to passing inspection and meeting building code.

What Makes a Mortise Lock "Fire Rated"?

A mortise lock earns a fire rating through third-party testing against recognized standards, such as UL 10C, CAN/ULC-S104, or EN 1634-1, which subject the lock to extreme heat and flame exposure to verify it continues to function and hold the door closed. Manufacturers like Keyman Lock design their fire rated mortise locks to meet these benchmarks alongside general mechanical standards like ANSI/BHMA A156.13 (mortise locks and latches) or EN 12209 (the European mechanical performance standard).

For example, Keyman's M7 Series UL ANSI Grade 1 Mortise Lock meets:

• ANSI/BHMA A156.13 Standard for Mortise Locks & Latches

• ANSI/UL 10C & CAN/ULC-S104 Fire Rated for 3 hours

Meanwhile, Keyman's M5 Series CE EN Euro Mortise Lock is built for European commercial fire door mortise lock markets and meets:

• EN 12209 Grade 3

• EN 1634-1 Fire Rated for 4-1/3 hours

Why Do Fire Door Assemblies Require Fire-Rated Hardware?

Fire door assemblies must maintain their rated performance as a complete system, meaning every component—including hinges, closers, and locks—must carry a fire rating that matches or exceeds the door's rating. Installing a non-rated mortise lock on a fire door voids the door assembly's certification, even if the door slab itself is rated, which can result in failed inspections and code violations. This is why commercial fire door lock specifications should always reference the lock's individual UL, ULC, or EN fire test listing.

How to Select the Right Fire-Rated Mortise Lock

Choosing the correct fire rated lock depends on several project-specific factors:

1. Applicable Code and Region: North American projects typically reference UL 10C and CAN/ULC-S104, while European and Middle Eastern projects often require EN 1634-1 compliance. Confirm which standard your jurisdiction and project specification require before selecting hardware.

2. Required Fire Rating Duration: Fire door ratings commonly range from 20 minutes to 3 hours (or longer under EN standards). Match the lock's rated duration to the door assembly's rating—for instance, a 3-hour rated opening requires hardware certified for at least 3 hours, such as Keyman's M7 Series.

3. Door Profile and Lock Function: Mortise lock fire rating certifications are typically tied to specific door thicknesses, backset dimensions, and lock functions (e.g., classroom, storeroom, or exit function), so confirm the certified configuration matches your door specification.

4. Grade and Durability Requirements: Beyond fire rating, consider the mechanical grade (such as ANSI/BHMA Grade 1 or EN 12209 Grade 3) to ensure the lock withstands the daily traffic expected in commercial settings.

5. Compatible Trim and Accessories: Fire-rated mortise locks are generally certified as part of a listed hardware set, so escutcheons, cylinders, and trim should also carry compatible certifications.

Architects specifying hardware for high-traffic commercial buildings, such as hospitals, schools, and office towers, are better served by ANSI/UL-rated mortise locks like the M7 Series, while projects following European building codes are better suited to EN-certified options like the M5 Series.

Frequently Asked Questions