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First Line of Defence (Fire Doors)

Archived. Chiltern International Fire now trade as BM TRADA

Mark Gannon, Chiltern International Fire’s representative in Ireland, discusses the crucial role of fire doors in passive fire protection.

As a fire consultancy and test laboratory, Chiltern International Fire has in recent months noted a huge increase in interest in the use and maintenance of fire resisting doorsets. Building owners and employers are more aware of the need for regular risk assessments. In this context, monitoring the condition of the passive controls in place within the working environment is vital, especially if a building has undergone a change of use or substantial refurbishment.

A fire resisting doorset is the acknowledged first line of passive defence against the passage of fire through a building. A fire resisting doorset - the door leaf or leaves, the frame in which the door is hung, essential ironmongery, intumescent and smoke sealing devices - is required to perform one of three main functions:

  • To protect escape routes from the effects of fire, to enable the occupants to reach final exits.
  • To protect the contents and/or structure of the building by limiting the fire spread.
  • To permit fire fighting.

Although any closed door will have some delaying effect on the development and spread of a fire, a fire door must be proven to be capable of resisting the effects of a standard fire test for stipulated periods, usually 20, 30 or 60 minutes.

The single most important consideration for the specifier when choosing a fire doorset is that, if the worst should happen and a fire breaks out, the doorset will perform as it has been designed to do. Thankfully, most fire doors are never put to the ultimate test, but sadly of those which are, not all will come even close to doing the job they were intended to do. At Chiltern Fire, we have for several years been running ‘Fire doors explained days’, one-day training workshops which include a full-scale fire door test ‘live’ or on video. Delegates are often shocked to witness how poor installation or frame design, for example, can mean that a 60-minute fire door will fail to reach even half of that.

Fire doorsets are complex products requiring specialist knowledge and we have argued for many years that they should be manufactured and ideally installed by companies who can demonstrate through testing or third-party certification that they are expert in this field. We strongly recommend that specifiers choose wherever possible a manufactured doorset, rather than individual components which may not be correctly assembled on site.

While representative examples of intended fire door designs are required to be tested to BS 476-22: 1987 Methods for determination of the fire resistance of non-load bearing elements of construction, or to BS EN 1634 – 1: 2000 Fire resistance tests for door and shutter assemblies, this is rarely if ever feasible for doorsets upgraded in situ. In most cases, regulatory authorities are willing to accept an assessment of likely performance in lieu of a test result.

Chiltern Fire would argue that it is often preferable - and safer - to install new and third-party certified doors when refurbishing or upgrading the passive fire protection within existing buildings. That said, there are circumstances where it is necessary to retain the existing door, for example to comply with fire regulations when the use of the building has changed. Upgrading might also be considered to meet either retroactive legislation or new insurance requirements.

In such cases, existing doorsets may be upgraded to achieve the required fire resisting performance, but it is vital to look at each case individually, as existing doorset installation and the condition of the leaves and the frame will vary from building to building. Given this, it is recommended that existing doorsets are independently surveyed - by an expert like Chiltern Fire - where either an enhanced fire resistance is required or general confirmation of their performance is needed.

What of new fire-rated doorsets? It will inevitably crop up that a new fire-rated doorset will be needed because of a change in compartment lines or because the existing doorset is inadequate for upgrade. But it is not quite as easy as buying any standard leaf and frame and blindly fitting them into the prepared opening. These types of performance products are not just a piece of wood in a hole and will only provide the desired integrity if installed in accordance with the requirements of the test/assessment data. Consequently, it cannot be assumed that all fire resisting doorsets can be used in all situations.

There have been cases where installed doorsets have been rejected quite simply because the main construction of the structural surround is incompatible with the doorset – and this will vary from one manufacturer to another.

When specifying a new doorset for installation, the main structural surrounds must be taken into consideration, as an incorrect assumption can and will cause hefty and unacceptable time delays to the client. Equally, installers and specifiers are faced with similar pitfalls if they assume that any door frame can be married up with any door blank.

So how would one police this to ensure that the beautiful, new, expensive door leaning against the staircase ready for installation will be acceptable? The answer to this is not new by any stretch of the imagination, but is one that has increasing weight in the specifying industry – third-party certification. In ensuring that the products themselves are not only manufactured to a consistently high standard time after time, schemes such as BM TRADA’s Q-Mark for fire doors will ensure that all installation details of either the doorset (frame and leaf etc) or the additional components required to complete the doorset are passed directly onto the specifier or installer.

It is not necessarily always appropriate to use ‘standard’ doorset details. Doorsets form a large, visible part of our internal (and external) built environment and consequently bespoke designs and elevations can not only encourage our enthusiasm for the place in which we work, but also fire our appreciation for good design.

It is essential, however, that bespoke constructions are technically assessed using project specific assessment reports, based on primary test data, which will (when appropriate), provide cover for architecturally pleasing doorset creations. These reports spell out the required construction and installation methods required for the proposed design to achieve the desired integrity performance. Whilst these types of constructions should not be justified by anyone other than a technically competent fire engineer, one should not necessarily allow free thinking to be bound by factory standard details.

In construction it is so important to get it right first time – the design and installation of fire doorsets is a particular case in point.

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