Fire Doors and Letterboxes – Everything You Need to Know

Fire doors and letterbox systems are a vital part of your building’s fire protection plans. Your doors – whether internal or external – will form part of your escape route and so it is crucial that as many of them as possible are available for use during an evacuation. Fire retardant doors and letterboxes can also dramatically decrease the spread and development of a fire, containing it in a particular area and lessening the damage to life and the building as a result.

In addition, many arson attempts are started through doors and letterboxes, making it even more important that your premises are protected.

This guide aims to provide information and advice on various types of letterbox systems, examining the benefits of passive fire protection methods and how they can protect your building – and everyone who lives or works within it – from the threat of fire.

Passive Fire Protection

Passive Fire Protection (PFP) is an umbrella term for all fire safety products which attempt to contain or slow the spread of fire. They usually involve the compartmentalisation of the building, separating it into various areas through the use of fire-resistant walls, floors and doors. This helps to prevent or slow the development of a fire, limiting the building damage and offering more time for occupants to evacuate safely.

Fire resistant letterboxes are a seemingly small, but hugely important, example of passive fire protection. All fire doors which require a letterbox function (such as front or external doors) must feature a fire-retardant letterbox system in order to maintain their purpose.

Fire Retardant Letterboxes

There are various types of fire retardant letterboxes – most commonly intumescent letterbox systems and anti-arson letterboxes. Performing differently and offering various functionalities, they both aim to protect your environment from the threat of fire. However, one may be more suitable for your specific needs and environment.

Intumescent Letterbox Systems

These letterbox systems use intumescent technology to protect your property. Primarily designed to contain the spread of fire, they are offered as 30 or 60 minute fire rated letterboxes and, as such, will protect your building for half an hour or an hour respectively.

Intumescent letterbox systems work by containing a high performance intumescent liner within the letterbox frame which, in the event of a fire, will expand and seal the letterbox aperture. This will then maintain the fire door’s integrity.

Intumescent letterboxes are most commonly used in commercial environments, such as retail outlets and offices. Rather than prevent deliberate arson attempts, they are more often used to compartmentalise your environment in the event of a fire, supporting your fire doors in an effort to stop its spread to other areas and allow employees, clients and visitors to escape safely and effectively.

Tested to standards BS 476 Part 22 (1987) and EN 1634-1 (2000), intumescent letterbox systems are available in a range of sizes and offered in a variety of finishes and frames, including polished silver, polished gold, chrome and stainless steel.

Anti-Arson Letterboxes

Anti-arson letterboxes and fireproof mail bags help to protect homes and commercial buildings from the threat of deliberately started fires. They work by containing any flammable liquid poured through the letterbox (such as petrol) and are also designed to extinguish a fire. This is either achieved through the installation of an integrated automatic fire extinguisher, or as a result of the bag’s material swelling through heat and subsequently suffocating the fire.

Anti-arson letterboxes are particularly useful for areas or individual properties susceptible to arson and vandalism. Therefore, they are often used in homes subject to threat, as well as commercial properties wishing to further protect their business from fire.

There are various anti-arson letterboxes available, including complete letterbox systems or mailbags which can be attached to an existing letter opening. They are offered in a variety of sizes and finishes and can be installed in almost any type of door, including wooden and uPVC doors.