The Regulatory Reform (Fire Safety) Order 2005 (RRFSO) charges the responsible person(s) in control of a non-domestic building or the shared / communal areas of houses in multiple occupation (HMOs) with the safety of everyone, whether working, visiting or living there. The HM Government entry level guide to the RRFSO, “A short guide to making your premises safe from fire” (June 2006), notes that “the responsible person, either on their own or with any other responsible person, must as far as is reasonably practical make sure that everyone on the premises, or nearby, can escape safely if there is a fire”.
Fire separation and compartmentation are key to containing fires and protecting escape routes; the following is an extract from the local government LACORS publication “Housing – Fire Safety: guidance on fire safety provisions for certain types of existing housing” (see pp 19–21):
“19.1 In addition to providing a protected escape route, it is necessary to restrict the spread of fire and smoke from one unit of accommodation to another. This is termed compartmentation. Fire-resisting construction enclosing each unit of accommodation creates a compartment that will contain fire and smoke within it for a period of time, leaving adjacent units free from the effects of fire during that time.
19.2 The recommended standard of fire separation in the types of premises of normal risk covered by this guide is generally 30 minutes… Where the fire risk assessment identifies specific higher risks then a higher standard of fire resistance may be required (usually 60 minutes) or additional fire safety measures should be installed… Attention should be paid to any ductwork that passes through the separation. This will require protecting to the same standard of fire resistance as the partition itself.”
Passive fire protection (PFP) is a fire rated means of ensuring that the smoke, flames and hot gases of a fire are contained for a period of time that is long enough to enable not only the safe evacuation of the occupants but also the arrival of the fire services. It also acts to reduce the spread of the blaze to make the building as safe as possible should fire fighters have to enter it. So much of fire safety protocol revolves around the swift and safe evacuation of the occupants of a building but it is also of vital importance to consider the risk to fire fighters who have to confront the blaze when everyone else has escaped. PFP measures can therefore be seen to fulfil the duty of care of the responsible person(s) to everyone in a fire situation, including members of the emergency services.
Government guidelines note that there are several methods and products available that will achieve the required standard of fire resistance, some of which may be more appropriate than others for the existing construction of your premises. If there is any doubt about how your building is constructed, then it is important to ask for further advice from a competent person (Fire safety risk assessment: sleeping accommodation, May 2006, p 122). In respect of new build, extensions, structural alterations, etc, all work should be carried out in accordance with The Building Regulations 2010, Fire Safety, Approved Document B.
It is interesting to note that, in respect of the structural aspect of fire safety, the approach of the regulations in Volume 1 (Dwellinghouses) and Volume 2 (Buildings Other Than Dwellinghouses) is very similar. This is because PFP measures are implemented with the purpose of containing / compartmentalising / retarding the spread of fire, a guiding principle that extends across all buildings, regardless of their use and function.
PFP and the Building Regulations
In respect of internal fire spread (structure) The Building Regulations 2010 stipulate the following (Requirement B3):
• Where reasonably necessary to inhibit the spread of fire within the building, measures shall be taken, to an extent appropriate to the size and intended use of the building, comprising either or both of the following –
(a) sub-division of the building with fire-resisting construction;
(b) installation of suitable automatic fire suppression systems.
• The building shall be designed and constructed so that the unseen spread of fire and smoke within concealed spaces in its structure and fabric is inhibited.
Fire Safety, Approved Document B, Volume 2 – Buildings Other Than Dwellinghouses: p 67
In respect of compartmentation, Section 8 of the Regulations states (p 71) that the object is twofold:
a. to prevent rapid fire spread which could trap occupants of the building; and
b. to reduce the chance of fires becoming large, on the basis that large fires are more dangerous, not only to occupants and fire and rescue service personnel, but also to people in the vicinity of the building.
In respect of the protection of openings and fire-stopping in order to inhibit the spread of fire, 10.2 of the Regulations states (p 85):
If a fire-separating element is to be effective, every joint or imperfection of fit, or opening to allow services to pass through the element, should be adequately protected by sealing or fire-stopping so that the fire resistance of the element is not impaired.
The Building Regulations then proceed to identify two main types of opening that could compromise the integrity of a fire resistant structure: openings for pipes (10.5); and ventilation ducts, flues, etc. (10.9). At 10.17, additional provisions in respect of fire-stopping are detailed as follows:
a. joints between fire-separating elements should be fire-stopped;
b. all openings for pipes, ducts, conduits or cables to pass through any part of a fire-separating element should be:
i. kept as few in number as possible; and
ii. kept as small as practicable; and
iii. fire-stopped (which, in the case of a pipe or duct, should allow thermal movement).
PFP product overview
As noted above, as well as internal doors, every service that is installed in a building, such as water pipes, electrical sockets, cable trunking and lighting units, can compromise the fire resistance of a compartment / room by creating openings in its walls, floor and ceiling. The role of PFP is to seal the gaps these penetrations create should the worst happen and fire break out. All products designed to fulfil this criteria are fire rated, i.e. certified to resist fire for a specified length of time, which can be anything from 30 minutes to 4 hours. They all include an intumescent material, which remains dormant, or passive, during normal conditions but swells to many times its original size when exposed to the heat of a blaze.
Although it is not possible to review every type of product in this article, a few examples are given below to illustrate the way in which PFP fulfils the requirements of the RRFSO and Building Regulations.
Fire doors, whose purpose is to contain a fire / protect a designated fire escape route, should be fitted with intumescent fire and smoke seals, either around the edges of the door leaf or the frame. These seals are an integral part of a fire door structure and ensure that, not only is the spread of fire prevented, but also and more importantly the ingress of cold smoke in the early stages of a fire. Smoke is known as the silent killer as it can overwhelm the occupants of an enclosed area long before the heat and flames of a fire are sensed.
The hot gases of a blaze can also move swiftly around a building, undetected at first, for example through air conditioning ducts. Intumescent air transfer grilles, which are typically 30 or 60 minute fire rated, allow air to circulate freely around a building under normal conditions, but the intumescent material swells and creates a barrier to restrict the passage of hot gases in a fire situation. They are suitable for use with both fire rated doors and compartment walls.
Intumescent pipe wraps and collars are designed for use on plastic pipes that pass through masonry floors and walls; the intumescent material expands inwards in a fire situation to squeeze the collapsing pipe until the opening is completely sealed.
Intumescent downlighter covers and fire hoods / canopies for recessed light fittings prevent fire from penetrating the ceiling void and thus preserve the fire resistant integrity of the ceiling; they are typically 30 or 60 minutes fire rated.
Electrical sockets in walls and skirting boards are another vulnerable point in a fire rated compartment; intumescent socket box inserts / covers expand to fill the electrical box in a fire, preventing the spread of flames, smoke and hot gases.
When choosing PFP products, it is important to ensure that they have been tested to the relevant, current British standard: for example, BS476-20: 1987 “Fire tests of building materials and structures: method for determination of the fire resistance of elements of construction (general principles)”.
It is also recommended that CERTIFIRE approved products are used. CERTIFIRE is a national certification body that specifically operates in the field of PFP. Its quality mark reflects, not only compliance with the minimum regulatory requirements for CE Marking, but the additional requirements of ISO9001:2000 certification and independent audit testing. The technical specification against which certification is awarded is known as the Technical Schedule, which describes the design and performance features a particular product must exhibit in order satisfactorily to fulfil its fire protection function.
Existing buildings: what if an upgrade is impractical?
Although it is best practice to upgrade an existing building in terms of its fire resistance, this approach may not always be feasible. In such cases, it will be necessary to adopt compensatory measures, in respect of which the Local Government Association publication “Fire safety in purpose-built blocks of flats” (May 2012, p 72) offers the following guidance:
“As a benchmark, the minimum levels of fire resistance for compartment walls and floors for existing blocks of flats should be:
• Three-storey – notional 30 minutes fire resistance
• Four- and five-storey – full 30 minutes fire resistance
• Six-storey and above – 60 minutes fire resistance
In certain situations, in existing blocks where these periods of fire resistance are not met or cannot readily be achieved by upgrading, compensatory fire protection measures may need to be considered. These measures might include one or more of the following:
• Improving the means of escape by providing an alternative escape route or upgrading protection to the enclosure of escape routes to current benchmark design standards, e.g. FD30S doors
• Provision of an automatic fire detection and alarm system to compensate for the reduced levels of fire protection
• Provision of a sprinkler, or other suitable fixed automatic suppression system”