Building Control ...
Fire Safety
- Introduction
- Means of Escape/Warning
- Dwellings
- Loft conversions - Guidance on existing bungalows and two storey houses
- Flats and maisonettes
- Commercial/Industrial/Non-Residential Buildings
- Management of Premises
Note – The new Approved Document B : Fires Safety was introduced in April 2007 –
Volume 1 - Dwelling houses
Volume 2 - Buildings other than dwelling houses
Introduction
The provisions of Part B of the Building Regulations deal with different aspects of fire safety with the following aims:
- Ensure that 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 Escape/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.
Dwellings
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 dwellings
- Habitable rooms on the upper storey to have an emergency egress window with an unobstructed openable area of 740mm x 450mm positioned maximum 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 enable 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.
Loft conversions - Guidance on existing bungalows and two storey houses
Loft conversions have become a very popular way of extending domestic properties. Experience, however, shows that this seemingly simple concept can cause major problems in complying with the Building Regulations.
Before embarking on any building work, including loft conversions, it is advisable to obtain professional advice from an Architect, Surveyor and/or Structural Engineer. North Tyneside Building Control have staff on hand to discuss the proposals prior to making a Building Regulation application.
Below is a brief guide to areas of construction which will require particular attention when planning the actual conversion works:
Roof
The construction of the existing roof will be a major factor in deciding what is achievable in changing the loft area into a ‘liveable space’.
These alterations will inevitably mean adapting the structure to form either dormer windows or roof lights. It will generally be necessary to provide an engineer’s design to show how the additional loadings on the roof or supporting structure will be maintained.
A further consideration is the placing of insulating materials within the roof slope and the precautions necessary to prevent damage from condensation in the void area.
Floors
The existing ceiling joists are unlikely to be able to support the additional loads from a new floor for domestic use.
The new floor elements must have adequate support and should be sized and spaced according to the spans involved.
This new element of construction within the dwelling will need to be afforded an adequate level of fire resistance to ensure its stability in case of fire.
Walls
The new floor must be supported by load bearing walls adequate to carry the new loads and must have a suitable foundation. A full structural appraisal by an appropriately qualified professional is therefore recommended.
Fire resistance of the walls, both new and existing, is again of major importance and expert advice will again be needed.
Depending on the layout, the new doors will have to be fire doors or in some cases existing doors ‘fitted with’ self-closing devices.
Generally any existing glazing contained in the walls of the stairway enclosure must be replaced by fire resistant glass.
In the case of the walls to a dormer window it will be necessary to ensure they are suitably weatherproofed and insulated. If the dormer is close to an adjoining property it will be necessary to provide additional fire protection to this element from both inside and outside.
Stairs
The preferred access to the new room should be via a traditional straight flight of stairs with landing top and bottom. Spiral staircases, fixed ladders and alternating tread stairs are considered in special circumstances, however only where there is insufficient space to accommodate a standard stair.
Suitable guarding and handrails must be provided to the stairs and adequate headroom maintained, usually measured at two metres vertically above the flight.
Escape in case of fire
The principal route of escape is provided by the staircase, which must discharge to a suitable final exit, normally a front or rear door. The staircase should be fully protected for its full height for 30 mins - including doors to habitable rooms.
Where an 'open plan' layout exists at ground floor level it may be necessary to provide a new partition to enclose the escape route.
NB. Your attention is drawn to the section on Fire Safety guidance. Recommendations contained within this section regarding mains operating smoke detectors should be followed to ensure early warning of an outbreak of fire.
Dwellings with more than two storeys
In dwellings of increasing height above ground level more complex provisions are required because emergency escape from upper windows becomes increasingly hazardous – this entails either designing the staircase as a protected route of escape or by providing an alternative stair.
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.
- At least 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.
See BS5839-6: 2004 Fire Detection And Fire Alarm Systems For Buildings for detailed guidance.
Risk areas in dwellings
- 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 the level of the garage floor or the floor laid to fall away from this door to allow any fuel spills to flow away from 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.
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 enabling 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 dwellings adjacent 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 within 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 back 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 ensure 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 ensure 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 installations in separate flats.
- Maisonettes to be treated similar to two storey houses.
See BS5839-6: 2004 Fire Detection And Fire Alarm Systems For Buildings for detailed guidance.
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:
- Ensuring that there are no weaknesses at the junctions of all fire compartments and
- Ensuring at all openings in fire resistant walls/floors for services to pass through are adequately sealed.
Commercial/Industrial/Non-Residential Buildings
The planning of the means of escape/fire safety design in these building 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 occurring 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 but in all other buildings 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 Fire Strategy reports and fire design layouts of the project are submitted to Building Control as part of the Building Regulation submission for new buildings - indicating means of escape strategy, fire separation, automatic fire detection provision, management responsibility emergency lighting provision and fire alarm details.
MANAGEMENT OF PREMISES
The Approved Document has been written on the assumption that the building concerned will be properly managed.
Building Regulations do not impose any requirements on the management of a building. However, in developing an appropriate fire safety design for a building it may be necessary to consider the way in which it will be managed. A design which relies on an unrealistic or unsustainable management regime cannot be considered to have met the requirements of the Regulations.
Once the building is in use the management regime should be maintained and any variation in that regime should be the subject of a suitable risk assessment. Failure to take proper management responsibility may result in the prosecution if an employer, building owner or occupier under legislation such as the Regulatory Reform (Fire Safety) Order 2005.
