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  • Dan Gibbard

The difficulty of meeting Fire door standards in Dwellings

A desperately tragic event in June 2017 brought much attention to Approved Document B. Rightfully this has meant the tightening and clarification of parts of the document that were previously ambiguous enough to allow for potentially dangerous decisions to be made during the specification and construction of, as it turns out, as many as 9,000 buildings in the UK fitted with ‘unsafe’ cladding [1]. The cladding was only part of the failures at Grenfell, also in the spotlight were fire doors. Their potential misspecification and lack of maintenance [2]. Change has occurred because of the new ‘Building Safety Act’, which amongst other things has sought to address the way fire doors are specified and maintained. But the focus of the reforms in the wake of Grenfell is focused primarily on ‘higher risk’ buildings, those of significant height and managed by a ‘responsible person’. Are there any ambiguities in Approved Document B that could be addressed that affect our core housing stock of ‘low-rise’ houses? During a recent CPD at our practice, an ex-Fire Fighter gave a comparison between two alarming statistics. Tests conducted in North America n 2007 concluded that the average time from the initiation of a smoke detector to the point of a fire ‘flashover’ was between 4 and 4.5 minutes. A ‘flashover’ is the point during a fire where every combustible surface in a space rapidly, and simultaneously, ignites [3]. Sounds terrifying; a quick YouTube search will allow you to conclude it is exactly as bad as it sounds! Perhaps it should be noted that not every fire has a ‘flashover’ event, but to put it into perspective when it does occur, on average it happens in about half the amount of time that it takes the Fire Brigade to reach the scene of a dwelling fire (7 to 8 minutes) [4]. In the event of a fire, doors specified in a low-rise, single-family domestic setting are generally there to provide a protected escape route to a place of safety outside. As was the case at Grenfell, the understanding around the importance of proper specification and maintenance of fire doors in low-rise domestic settings seems to be lacking and is not helped by the difference between the requirements of Part B compared to the offerings of the building materials market.

Approved Document Part B, Appendix C1 is clear in that fire door sets should meet the fire resistance periods when tested to BS 476-22 or BS EN 13501-2. In a lot of cases, Part B requires a door of only 20-minute fire resistance for a single-family dwelling (see AD Part B, Table C1). However, fire door manufacturers for reasons of economy no longer test doors for a 20-minute rating, instead opting to begin their offerings at 30 minutes. Speak to the manufacturers of fire doors and they will tell you that their doors are tested with intumescent seals in place, and to fit the door without voids, the fire certification of the door. Until quite recently the advice from the BCA (short for the Building Control Alliance, the group that provides guidance on industry best practices to Building Control professionals) for fire doors noted; For doors opening onto a protected escape route situated within a single family dwellinghouse or within an individual flat, FD30 door leaves that have been tested as part of a set incorporating intumescent edge protection are acceptable when installed with or without intumescent edge protection. Having been the eminent guide to which many Building Control Bodies referred since it was published in January 2013, Technical Guidance Note 9 (from where the above was quoted) was quietly ‘revoked’ in January 2022 without explanation [5]. Is it time to remove the space for interpretation and update 30-minutePart B so that a 30-minute door becomes the minimum standard in these situations, and clarify the grey area on intumescent seals? Is it time for better industry education that the door leaf itself is the tip of the iceberg in ensuring that a fire-rated doorset works as expected? Where the door also needs tested & fire rated ironmongery, door linings that are installed with appropriate intumescent sealant (not the same as intumescent seals), a gap around the leaf that is within tolerance, and a lining/frame/stop that matches the specification stipulated by the door leaf manufacturer. Much like changes to Part L that require photographic evidence of the proper installation of the thermal envelope, why not the same for potentially life-saving fittings covered by Part B? Much could also be made of the advice that exists, some of it official, for retaining existing doors and, or frames on protected escape routes and assuming them to be of adequate fire performance. That is perhaps a topic in its own right but equally worthy of investigation and unfortunately, criticism, in the context of the low-rise dwelling renovation & extension sector.

You have likely heard the statistics before, but it’s not typically flames that cause death. The most common cause of fire-related fatalities (where the cause of death was known) is being overcome by gas or smoke [6]. Fire doors can help prevent the proliferation of smoke through a dwelling and can even suppress the initial development of a fire by restricting the amount of Oxygen available to it too. But not when they are left open. There is no obligation in a single-family dwelling to fit doors with automatic closers. As little as two or three breaths of smoke can be enough to seriously impair judgement or even cause unconsciousness [7]. With that in mind, early detection is obviously key. Smoke’s main adversary? The humble smoke alarm. For the majority of new dwellings that don’t fall into the category of ‘larger homes’, or where the occupants of the dwelling are not at special risk from fire, Part B is content for fire detection to exist only within the circulation spaces of the dwelling (a Grade D2, Category LD3 system). While there is some logic in an audible alarm being located in a common area of the home where it will likely be most easily heard. This minimum requirement would appear to be the antithesis to the principle of ‘early detection’. Whereby only once smoke has reached the area typically designated as the route of escape from a dwelling, does the fire detection system alert you to danger? The obligation for rented accommodation (irrespective of the building regulations) is no better. The recently revised ‘Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022’ only requires one smoke alarm on each storey of a house used as living accommodation. The most common room of origin of fatal dwelling fires is the living room. Fires starting in the kitchen are the most likely to result in severe casualties [8]. Cooking appliances are the leading cause of house fires [9].

Is it time for Part B to require all new builds, major extensions and renovations of dwellings (irrespective of their prospective owners or tenants) to have a detection system that covers more than just ‘escape routes only’? A 2019 London Fire Brigade article stating ‘smoke alarms in bedrooms are vital’ would suggest so [10]. The Building Regulations are not shy in imposing new regulations that will inevitably lead to additional construction costs (for example, recent and future earmarked changes to Part L that improve thermal efficiency). Mains-powered, interlinked smoke or heat alarms now cost as little as £15 per unit.


 

[3] https://www.ukfrs.com/guidance/search/flashover-backdraught-and-fire-gas-ignition [4] https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/952010/response-times-fires-england-1920-hosb0121.pdf [5] https://buildingcontrolalliance.org/guidance-note-9/ [6] https://www.gov.uk/government/statistics/detailed-analysis-of-fires-attended-by-fire-and-rescue-services-england-april-2021-to-march-2022/detailed-analysis-of-fires-attended-by-fire-and-rescue-services-england-april-2021-to-march-2022 [7] https://www.cheshirefire.gov.uk/public-safety/campaigns/awareness-campaigns/dont-drown-in-toxic-smoke [8] https://www.gov.uk/government/publications/an-in-depth-review-of-fire-related-fatalities-and-severe-casualties-in-england-2010-to-201819/an-in-depth-review-of-fire-related-fatalities-and-severe-casualties-in-england-201011-to-201819 [9] https://www.morganclark.co.uk/about-us/blog/uk-house-fire-statistics/




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