The prevention of fire and the control and elimination of it in the event of an outbreak are two of the most important considerations for anyone working in the construction industry. The safety of anyone inside a building and their secure route out is the top priority, and there are stringent regulations in place which are intended to cover every eventuality.
All new and refurbished commercial and domestic buildings are required to incorporate fire prevention to meet these regulations, and at the completion of a project, the designs are inspected by Building Control and tested for compliance.
The go-to material for fire prevention was, of course, asbestos, the dangers of which we have covered in our recent blog, The UK’s biggest workplace killer. Now that asbestos is banned, there is a raft of different fire prevention and protection solutions which we’ll explain below.
Fire resistant materials
Fire resistant materials used in construction include plasterboard, concrete, gypsum, cast iron and natural products which have been treated with flame-resistant chemicals. Nothing is entirely fireproof, but these materials can stave off fire for long enough to enable people to escape or be rescued. Intumescent paint, which is a type of fire-resistant coating which swells or ‘intumesces’ when heated to over 120 degrees celsius, can also be applied to structural steel columns and beams as well as louvres and cells for doors. It will usually give an hour’s leeway before a fire takes hold. The chemicals within the paint create a mass of small bubbles forming a thick layer of insulation over the surface below, which protects the structure from the fire and can also prevent collapse of load-bearing steel.
Intumescent paint is also regularly used for protected areas within large developments such as staircases, which are crucial as a route to safety in the event of a fire, and also as a route for firefighters to access the blaze.
Disabled refuge areas
If a building has more than one floor, it’s required to have a disabled refuge area, where a disabled person who can’t access a fire escape or other means of escape can wait until rescued. It’s worth noting that a small business with no disabled employees might not see the necessity of this, but other people, for example pregnant women and people with temporary injuries such as a broken leg, might also find an escape route impossible. The refuge should be large enough for a wheelchair user and should contain a special foldable wheelchair which makes descent of the stairs easier for rescuers. The refuge area should also contain a control panel with a button which a user can press to alert firefighters of their position, a speaker and a microphone.
Firebreaks and fire control methods
A firebreak is an intentional gap within the structure of a building which helps to slow or stop a fire and consists of a solid wall from floor to ceiling so smoke and flames can’t get through a gap. It can be one or more rooms, spaces or mezzanine levels which have built-in fire resistance, commonly between one and two hours before eventual ignition.
If a mezzanine level is inserted as a firebreak, it can be covered with intumescent paint, or lined with fire-resistant plasterboard instead of a grid of ceiling tiles, to create a sterile void to starve a fire.
Fire collars and fire dampeners are both effective means of fire control. A fire collar is a device which is used where plastic pipes have to pass through fire compartment walls and floors. The collar, usually made of stainless steel and containing intumescent material, is fitted around the pipe and attached to a nearby wall or floor. When a fire takes hold, the plastic pipe will begin to melt, whereupon the collar expands, and seals the hole left behind, preventing fire and smoke spreading through to the next area.
Fire dampeners are utilised in heating, ventilation and air conditioning ductwork to prevent the spread of fire inside the ducts. They can be linked to a fire alarm, and when it’s activated, or when they detect unusual heat, they automatically close up. Many commercial developments have substantial quantities of ducting within which fire can advance rapidly, so dampeners are a vital firefighting tool.
A fire curtain, such as one you’ll see lowered in the interval at the theatre, is a flexible fire-resistant barrier which is stored in a ceiling void and activated to block a large opening in the event of a fire. Other types of fire barrier can also be inserted which hold back fire for up to four hours, preventing spread and helping fire services to contain a blaze, and fireproof cloth containing a densely packed mesh can also be utilised. Lighting fire hoods are protective covers made from intumescent material which are installed over downlights to retain the fire-resistant integrity of the ceiling.
Hidden voids within a development can help fire to spread; an ablative-coated fire batt is a useful solution. Fire batt is a fire-resistant board used to seal the spaces around services passing through fire compartment walls, floors and ceilings. Ablative coating is a fire-resistant coating which chars and fuses together at high temperatures, forming an insulative barrier, and can be applied by spraying or brushing.
Fire doors and fire escapes
Property owners are required by the Regulatory Reform (Fire Safety) Order 2005 (RRO) to fit all premises, apart from private homes, with appropriate fire doors. These are usually rated FD60, meaning that they give 60 minutes of fire resistance. They are built with fire-resistant hinges and intumescent strips (sometimes combined with smoke seals) round the door which close up the joint if heated. Fire doors have automatic closure in all but a few circumstances. For these, a fire door with magnetic holdback is suitable; this keeps the door open normally using a magnetic mechanism, but closes it in the event of a fire alarm being activated. Fire doors should have fire-rated ironmongery for door handles etc, and this should always match the fire rating of the door. Fire ratings can range from 30 minutes to 120 minutes of fire resistance.
In a building with more than two stories, fire escapes should be fitted in accordance with RRO regulations. They should be designed for the correct volume of people within the building, as well as allowing for visitors. Building owners should calculate the occupancy for the size of the premises and ensure the numbers are not higher than the maximum number an escape route can accommodate. If the number of occupants in a building increases beyond the original calculation, fire doors may have to be widened and additional fire escapes put in.
Sprinkler and smoke extraction systems
In buildings three or more stories in height, basements exceeding 2550 sq ft in new buildings and all new commercial buildings 5000 sq ft or larger, the insertion of a sprinkler system is mandatory. Refits on existing buildings which increase the square footage to over 12,000 sq ft also need to have them. A mist sprinkler system uses compressed gas which is pumped through the sprinkler pipe, creating a heat absorbent mist vapour when water is released through the sprinkler head. As the mist is very compact, it cools the room and removes oxygen which is fuelling the fire. Mist sprinklers are popular because they cause less damage to the building and its contents if activated.
Basements need particular fire safety attention and smoke extraction systems, which remove smoke, heat and chemicals caused by combustion, and are an effective means of fire protection. They use duct systems which extract smoke through grilles on the ventilation ducts.
Fireman’s switch
When a fire has broken out in a building, it’s crucial for the fire brigade to be able to disconnect power from high-voltage devices which could prove dangerous. A ‘fireman’s switch’ is usually sited by the main entrance of a building. This is a simple on-off switch which can be operated on arrival by firefighters and can also be used to turn on high-powered basement extractor fans to draw smoke out. In this event, lighting can switch over to a battery-operated back-up in order to help people trying to leave the building.
Fire and smoke alarms
All commercial buildings must be fitted with fire alarms and smoke alarms, and tenants must ensure fire extinguishers are in place. Fire regulations also cover building sites where a new build or refit is being undertaken. A person must be nominated to manage the key issues such as risk assessment, means of warning, means of escape and means of fighting the fire. An alarm system must be fitted within the development, or if it’s at an earlier stage, an air horn or electronic sounder must be to hand.
The subject of fire alarms could probably take up another blog, as there are so many regulations to comply with and decisions to be made. There are eight individual fire categories set out in BS 5859 – fire detection and alarm systems for buildings. Five of these are in category L, which stands for Level, with L1 being the most comprehensive.
L1 – Maximum life protection
This is typically installed in large and complex buildings such as high-rise developments, hospitals, hotels, care homes and major industrial facilities, where a major degree of protection and control is required. An L1 system features detectors in all areas of a building, linked to a central alarm system which alerts everyone in the building in the event of a fire. It will usually include smoke detectors, heat detectors, sprinkler system monitoring, alarm control panels and notification devices such as sirens to warn occupants of the danger.
L2 – Additional life protection
Alarm systems in this category feature smoke detectors in all rooms which form part of an escape route, including corridors, plus all high-risk rooms such as kitchen, boiler rooms and plant rooms. It is usually installed in medium-sized commercial premises, schools and smaller factories, and could include smoke and heat detectors, manual pull stations, control panels, alert appliances and sometimes basic suppression system monitoring.
L3 – Standard life protection
This features detectors in all escape routes and rooms that open onto them, to ensure all inhabitants have enough warning to escape. It’s mostly utilised in smaller offices and commercial buildings containing stairs.
L4 – Modest life protection
This will just have detectors in escape routes and is suitable for buildings with ground floor rooms only.
L5 – Localised life protection
This is a system which is installed for a specific area of a building which might pose a particular fire risk, such as the storage of combustible items.
There is also the option of a manual system for small premises, which relies on the building’s occupants alerting everyone in the event of a fire and manually activating an alarm, usually by a break glass unit.
Want to know more?
All aspects of fire prevention and protection must be detailed in a building’s schedule of works, as well as in the owner’s manual.
At Oakwhite, our many years of experience in fit outs and refurbishments means there’s nothing we don’t know about fire prevention and protection. Ensuring the safety of all future occupants is arguably the most important part of any development. If you’d like to have a chat about your fire safety compliance, why not contact us by email or call us on 01403 586062 – we’d be happy to help.