Fire-rated doors: latched vs unlatched and what it means for you

Fire-rated doors can be latched or unlatched. Find out what this means for your specification process.



Fire-rated doors can be either latched or unlatched. At Wrightstyle, we provide both options.

The fundamental difference is the presence or absence of a latch – how, in other words, the fire door stays closed.

With a latched fire door, the closer shuts the door until the latch engages. With an unlatched fire door, the closer shuts the door fully into its frame and helps keep it closed during a fire.

This necessitates a difference in hardware. Latched doors typically have a mortice latch and lock and a door closer. By contrast, unlatched doors have a push-pull plate or another kind of unlatched hardware.

Your supplier will cover these basic differences. The important thing for you to know is how the latched or unlatched specification affects the overall fire performance of the assembly.

The way the door closes affects the door's maximum dimensions, its fire rating and other specification details. In this article, we show you how.

Why does the difference matter?

The difference between latched and unlatched fire doors matters because it determines how the door holds back fire. This in turn affects how the door is tested and specified in line with building regulations.

The latch on a latched fire door prevents the door from bowing or pushing open in the event of a fire. In the case of unlatched fire doors, however, the door relies on overhead door closers to stay shut.

Latched and unlatched fire doors must be tested and certified differently. A door assembly tested only in a latched configuration generally can't be specified as unlatched without appropriate supporting evidence. Conversely, testing in an unlatched configuration may also support a latched arrangement, provided the relevant evidence covers it.

That means a door assembly tested only as a latched door can't be specified as an unlatched door. This could compromise the door's fire resistance, potentially allowing fire to spread sooner than intended.

The difference can also influence where the fire doors are installed. Latched fire doors may be preferred where additional security or privacy is required, such as storerooms and entrances to private rooms.

Unlatched fire doors can be useful on high-traffic routes where ease of passage is important, including corridors in hospitals and other public buildings. However, the choice depends on the building's fire safety and access requirements, as well as the available tested doorset configurations.

Maximum size

The inclusion or exclusion of a latch can also affect the maximum permitted size. However, it's not as simple as saying an unlatched fire door has to be smaller than a latched fire door.

The crucial point is that the maximum size comes from the fire test for the doorset construction and configuration in question.

For a particular fire door, the manufacturer may have separate maximum dimensions for a latched single leaf, unlatched single leaf, latched double leaf and unlatched double leaf.



Fire rating

The presence or absence of a latch doesn't automatically change the fire rating. That's partly because the fire rating relates to the whole assembly: leaf, frame, seals, hinges, closer, latch, lock and other hardware.

Approved Document B – the primary source for the relevant guidance – insists on the importance of assessing the whole installed assembly. Small changes can make a difference to the rating.

The fire rating can change based on how the doorset stays closed during the fire. In the case of a latched fire door, the closer shuts the door until the latch engages – and once latched, the door is closed.

Unlatched fire doors, by comparison, rely on the closer to close the door fully in its frame. The closer keeps it there until heat-activated seals expand sufficiently to help maintain the door's integrity.

A tested unlatched doorset could have the same fire rating as a latched equivalent. However, you can't take a latched doorset, remove the latch and claim it has the same fire rating. The fire rating has to apply to the configuration as is – not as adjusted.

Specification

When specifying a fire-rated door – whether latched or unlatched – the crucial point is that the door, frame and hardware all form a doorset. Any component of this doorset can affect its overall fire performance.

Let's say you were specifying a latched door. You might request a self-closing fire-rated doorset with a particular fire-resistance classification, suitable intumescent seals and a compatible latch and lockset. The complete assembly must have supporting evidence for the required performance.

For an unlatched door, the specification would be similar. However, instead of a latch, you would need a closer suitable for maintaining the door in its closed position during fire exposure, with test evidence covering the proposed unlatched configuration.

The bottom line is that the latch or lack thereof should form a clear part of the specification. If you don't mention this, you could get a doorset with a component that invalidates the fire rating and is thereby non-compliant.

What building regulations cover fire doors?

In England, fire doors are primarily covered by Part B (Fire Safety) of the Building Regulations 2010. Approved Document B provides practical guidance on meeting these legal requirements, including fire-door positioning, performance standards and fire-resistance ratings.

Different regulations and guidance apply in Scotland, Wales and Northern Ireland.

How are fire doors fire-rated?

Fire door ratings indicate how long a doorset can maintain its fire resistance under specified test conditions.

Common ratings include:

• FD30: at least 30 minutes of fire integrity
• FD60: at least 60 minutes of fire integrity
• FD90: at least 90 minutes of fire integrity
• FD120: at least 120 minutes of fire integrity
  
  

Some specialist doorsets can achieve even longer periods of fire resistance.

Under the European classification system, doors may instead be rated E30, E60 and so on for integrity, or EI30, EI60 and so on where insulation performance is also required.

Smoke resistance is assessed separately, and the appropriate rating depends on the door's location and purpose. In every case, the classification must be supported by evidence covering the complete doorset and its intended configuration.

How Wrightstyle can help

At Wrightstyle, we provide tested fire-rated doors with glass in a range of configurations, including latched and unlatched options. Our steel glazing systems combine fire protection with the benefits of natural light, with options for integrity-only and integrity-and-insulation performance.

Not sure which arrangement is right for your project? Our technical team can help you understand the available configurations, fire-resistance ratings and specification requirements.



Get in touch with Wrightstyle today to discuss your project and find a suitable glazed fire door system.