The provisions of Part B of the building regulations deal with different aspects of fire safety with the following aims:
- Ensure the satisfactory provision of means of giving alarm of fire and achieving a satisfactory standard of means of escape for the occupants in event of fire.
- Limiting the spread of fire over internal surfaces in the building.
- Ensuring the stability of buildings in the event of fire. Ensuring the satisfactory standard of fire separation within buildings and between adjoining buildings. Inhibiting the unseen spread of fire in concealed spaces in buildings.
- Ensuring that external walls / roofs have adequate resistance to spread of fire over the external building surfaces.
- Ensuring a satisfactory provision for access for fire appliances to buildings together with the provision of facilities in buildings to assist fire-fighters in saving lives.
Means of escaping / warning
With regard to achieving a satisfactory standard of means of escape for the building occupants the following issues are the salient points:
- Routes to be provided of sufficient number and capacity which are suitably located to enable persons to escape to a place of safety in the event of fire.
- Routes to be sufficiently protected from the effects of fire by enclosure where necessary.
- Routes to be adequately lit.
- Exits from the building to be suitably signed.
- Appropriate facilities provided to either limit the ingress of smoke into escape routes or to restrict the fire and remove the smoke.
- Sufficient means of giving early warning of fire provided for the people in the building.
The above points relate to the construction of new buildings and alterations / extensions to existing buildings.
They assume that in the design of the building reliance is not to be placed upon external rescue by the fire service.
All guidance is prepared on the basis that in an emergency the occupants of the building should be able to escape safely without any external assistance.
The planning of the means of escape / fire safety design in these buildings is more involved.
The fire hazard of a particular type of building / contents and the kind of occupants together with their likely state of awareness have to be appreciated in the design.
The behaviour of a fire happening anywhere in the building and the response from the people put at risk has to be anticipated.
Although it is difficult to achieve a consistent standard of safety for buildings, which vary in size, location, usage, facilities and design similar initial approaches in achieving safety for the occupants apply:
- Horizontal escape design - the provision of satisfactory escape routes and final exits based upon travel distances, level of fire protection and maximum occupancy of the building.
- Vertical escape design - the number and protection of staircases based upon the building height/type and the maximum occupancy of the building.
As a general rule, in order to avoid occupants being trapped by fire / smoke there should be alternative escape routes provided from all parts of the building, except for circumstances where travel distances and / or occupancies can be restricted thereby allowing single routes of escape.
Lighting of escape routes - all escape routes should have adequate artificial lighting but many routes in buildings must also have escape lighting which illuminates the route of escape if the mains supply fails - this includes staircases, corridors, occupied rooms without windows and toilet areas.
Fire alarm / detection - the type of fire detection/alarm system to be provided is dependent upon the building type, type of occupancy, any sleeping risk and the means of escape strategy. The system must be designed to BS 5839: Fire Detection and Alarm Systems for Buildings.
Automatic fire detection must be installed in institutional / hotel buildings. In all other buildings, it is often strongly recommended as a compensatory feature to assist the means of escape design; as part of the operating function of fire protection systems; and / or as an integral part of the management / fire strategy for complex buildings.
It is essential that fire detection / warning systems are properly installed and maintained, therefore commissioning certificates must be provided to Building Control as evidence of quality, reliability and safety.
It is important that appropriate fire design layouts of the project are submitted to Building Control as part of the Building Regulation submission for new buildings and for major alterations / extensions to existing buildings - indicating means of escape strategy, fire separation, automatic fire detection provision, emergency lighting provision and fire alarm details.
Use of alternatives to the guidance in the approved document for Part B of the Building Regulations
A building's fire precautions may be designed in line with the recommendations of the appropriate part of BS5588 "Design of Fire Precaution in Buildings", the NHS Health Building's "Firecode" documents or "BS9999".
An acceptable fire precaution design must be one that is "holistic" for a given building and designers may not mix "Part B" guidance with "BS5588" or other documents guidance recommendations without taking great care.
New European standards and updated codes of practice for fire safety
During 2002 to 2004, there was a large scale updating and changeover to common european standards in fire safety testing within the European Union.
The UK made construction materials will increasingly be marked as tested to (BS) EN "numbers" rather than just BS "numbers".
There is no increase intended or change proposed in the actual technical performance requirements of Part B of the Building Regulations. But rather a major effort to open up the construction product supply market across Europe.
The Building Regulations aim to maintain safety - so all fire test and fire safety standards for building materials and systems will be tested against a common single standard.
The means of escape from typical 1 or 2 storey houses are relatively simple to provide with the specified provisions being:
- Suitable means provided for emergency egress from each storey.
- Adequate means of giving warning in event of fire provided.
Two storey houses
- Habitable rooms on the upper storey to have an emergency egress window with an unobstructed openable area of at least 0.332m² ie. 740mm x 450mm positioned not more than 1100mm above the floor.
- Habitable rooms (not kitchens) should open directly on to a hallway leading to the final exit or they are to be provided with emergency egress windows (size as above).
- Rooms which open only through another room (inner rooms) could cause problems for persons if a fire starts in the outer room - this situation arises in open plan layouts. This design is only acceptable for kitchens, utility rooms, bathrooms / toilets and rooms on ground and first floor levels with emergency egress windows.
Emergency egress windows / doors should allow people escaping to reach a place free from danger - preferably away from the dwelling but in some cases a large garden area can be considered.
Means of early warning
The installation of smoke alarms or automatic fire detection / alarm systems can significantly increase the level of safety by giving an early warning of fire to the occupants.
Smoke alarms to be mains operated on a dedicated electrical circuit with a secondary power supply.
Smoke alarms to be positioned in circulation areas between sleeping spaces; in places where fires are most likely to start such as kitchens or living rooms, to pick up smoke in the early stages of a fire. They should also be close enough to bedroom doors to be effective when people are asleep.
One smoke alarm per storey.
- If more than one alarm is used - they have to be interconnected so that detection of smoke in one unit operates the alarm signal in all units.
- Smoke detectors to be sited in circulation areas within 7.5m of doors to all habitable rooms.
Heat detectors are recommended in kitchens.
- Detectors to be ceiling mounted and at least 300mm from light fittings.
- Not to be fitted near heaters or air conditioning units.
- Not to be fitted in bathrooms, garages where steam or fumes could give rise to false alarms.
- To be positioned to make maintenance easy and safe - maintenance is the responsibility of the occupant.
Attached garages - they are to be separated from the house by half-hour fire resistant construction.
Doors giving access from garages to the house must achieve the same level of fire resistance and be self-closing - the door must be a minimum of 100mm above he level of the garage floor to prevent any leakage of petrol vapour into the house.
Windows situated in the wall between the garage and house must also afford the same degree of fire resistance.
The passage of any pipes or ventilating ducts through the walls or floors separating the garage from the house must be encased in fire resistant construction to prevent any fire spread.
Many households choose to extend into their loft space.
This provides specific problems in relation to fire. Please refer to the guide to extending your home.
Flats and maisonettes
Planning means of escape from flats and maisonettes involves a number of inter-related aspects which must be considered as a whole and not in isolation.
- Planning and protection of escape routes leading to safety both horizontally and vertically allowing people confronted by fire to turn their backs on the problem and make their safe escape without outside assistance.
- Fire resistant separation of escape routes.
- Segregation of risk areas.
- Means of detection of fire.
As there is a high degree of compartmentation in blocks of flats - the spread of fire from one dwelling to another is unusual.
It is therefore no longer assumed that in the event of fire it is necessary to evacuate the whole building, whole floors or even houses next to the fire.
However occupants of other dwellings in the building on fire may feel a need to escape especially if they live in dwellings close to the affected one. This is why the same emphasis is placed on the safety of escape routes outside of the dwellings as is within the flats.
Means of escape in the flat
A fire starting in the dwelling must not prejudice the escape of the occupants of the same dwelling.
It is essential, particularly in open plan dwellings, that kitchens are located remote from the flat entrance door so that occupants when escaping can turn their backs to the fire in these areas.
Main design features are:
- Protected entrance halls / private stairs in maisonettes.
- Limited travel distances in entrance areas.
Means of escape from flat entrance door to final exit
The aim is to make sure that a fire in any one dwelling will not obstruct the escape route of the occupants of any other dwelling.
This is achieved by providing fire protected stairways / corridors to make sure that fire / smoke does not spread to this part of the escape route.
In design, consideration has to be given to:
- Number of stairways.
Level of fire protection to the escape route.
- Travel distance from flat entrance door to the staircase.
- Risk areas.
- Emergency lighting in the shared escape routes.
- Smoke clearance in the staircase enclosure.
Means of early warning
The provisions indicated for single family dwellings all apply to flats with the following additions.
- No provision of detection in common areas.
- No requirement for the interconnection between installation in separate flats.
- Maisonettes to be treat similar to two storey houses.
Fire spread / compartmentation in flats
The spread of fire within these buildings can be restricted by dividing them into compartments separated from one another by fire resistant walls and floors.
The object is two-fold:
- To prevent rapid fire spread which could trap the occupants of the building.
- To reduce the chances of the fire growth.
This applies to every wall and floor separating individual flats from each other and also from other unoccupied parts of the building.
Careful consideration has to be given at both the design and build stages to maintaining the fire separation around the individual dwellings by:
- making sure that there are no weaknesses at the junctions of all fire compartments and
- making sure that all openings in fire resistant walls / floors for services to pass through are adequately sealed.
Many households choose to extend into their loft space.
This provides specific problems in relation to fire.
Please refer to the guide to extending your home.