Sprinkler Facts

Sprinkler systems have demonstrated their value in protecting life and property in industrial and commercial buildings for many years. The advent of sprinklers that operate at an earlier stage in the development of a fire have led to the introduction of residential systems designed for domestic dwellings.

A correctly designed and installed sprinkler system can detect and control a fire at an early stage of development and activate an alarm. Operation of the system will rapidly control a fire and reduce the rate of production of heat and smoke, allowing time for the occupants to escape to safety.

Residential sprinklers can offer a broad package of fire protection for householders, which protects not only lives, but has the added advantage of reducing property and contents damage. Sprinklers can help to reduce the overall expenditure on fire, by minimising the cost of ‘after care’ for fire victims provided by Health Authorities and Social Services and achieve this by adding to the quality of protection the Fire Service provides.

Residential sprinklers are a relatively new concept in this country. This module is therefore designed to explain what residential sprinklers are; what they do; where it might be appropriate to install a system; and answers some commonly asked questions.

How residential sprinklers operate:

A residential sprinkler system is a series of pipes (plastic or copper) and water spray heads designed to detect, intervene and suppress/control a fire when activated.
Residential sprinklers are individually heat-activated. They are connected to a network of piping which in turn is filled with water under pressure. When the heat of a fire raises the sprinkler to its operating temperature, usually between 57°C-79°C, a fusible link or glass bulb will activate only that sprinkler over the fire, thereby releasing water over the source of heat and walls, reducing the fire-size temperatures and levels of toxic gases within the room of origin.

The result is to keep a fire from reaching potentially dangerous and life-threatening proportions and giving early detection. Residential sprinklers operate automatically in the event of a fire, even if the householder is not home, releasing water directly over the source of heat and sounding the alarm. They help to extinguish a fire, but should this not happen the system will control the fire and slow its growth and reduce smoke and toxic fumes. This means that the fire service will be faced with a less severe fire and much less damage caused to the property. Most importantly the householder will have had time to escape.

British Standard for residential sprinklers:

The British Standard BS9251 gives recommendations for the design, installation, components, water supplies, commissioning, maintenance and testing of fire sprinkler systems installed for life safety purposes with additional benefits for protection in residential and domestic occupancies.

The scope of the BS9251 covers residential and domestic occupancies. For residential occupancies these include: apartments, residential homes, houses of multiple occupancy, blocks of flats, boarding houses, older people’s homes, nursing homes, residential rehabilitation accommodation and dormitories. For domestic occupancies these include: individual dwelling houses, individual flats, maisonettes and transportable homes.

The British Standard BS9251, the residential and domestic sprinkler specification can be obtained from: British Standards Institute, 389 Chiswick High Road, London, W4 4AL or Tel: 020 8996 9000

Experience of sprinklers
The vast majority of fire deaths and injuries happen in the home. About 35 years ago the United States started to use specially designed domestic sprinkler systems to save lives in dwellings. The results have been encouraging.

Although sprinklers are now commonplace in US dwellings, the US Government continues to support a nationwide campaign – Operation Life Safety – to encourage their installation. In one town in Arizona, all new homes have been required to be fitted with sprinklers for the last 25 years. Sprinklers now protect 40% of the dwellings in Scottsdale.

Earlier this century Scottsdale published a 10-year report, which showed:
• No fire deaths
• 80% reduction of fire injuries
• 80% reduction in property damage
• 95% reduction in water usage for fire control

It would be misleading to mention the American experience, however, without noting that many US homes are far more remote than most in the UK. In the US, firefighters may not arrive for some time in the event of a fire, so sprinklers are all the more important.

What role can sprinklers play in reducing dwelling-fire deaths and injuries?

The installation of residential sprinklers should be regarded as part of the overall Community Fire Safety package. The provision of a sprinkler system does not negate the need for other fire precautions or practical measures, which may include smoke alarms, escape routes and safe housekeeping practices. These are all key messages that brigades should continue to promote.

One of the most effective weapons in the Community Fire Safety armoury in recent years has been the smoke alarm. Since the Home Office and the fire service began promoting the greater use of smoke alarms in the mid-1980s, we have seen a steady fall in the number of dwelling-fire deaths. The smoke alarm is effective because it gives those vital few minutes’ warning of a fire to the occupants allowing them to escape before the fire really takes hold. However, the decline in the number of fire fatalities has not prevented an increase in the number of non-fatal casualties.

With properly installed and working smoke alarms, occupants are provided with an early warning of fire. Whilst this is the case for able-bodied and fit people, it is not necessarily so for the very young, disabled or mentally disadvantaged. These vulnerable groups in society may require additional protection from the devastating effects of fire, and burns.

Where might residential sprinkler systems be installed?

Although there is no requirement for sprinklers to be installed in domestic dwellings there are a number of scenarios where it may be advantageous for householders, local authorities or builders to consider fitting a system to ensure a greater protection from fire. These might include:

  1. where access to the premises may be more restricted than recommended in the Approved Document B of the Building Regulations, resulting in difficulties for fire-fighting appliances gaining access to the building and delaying firefighters in tackling a fire;
  2. in isolated areas where it would take the fire service some time to arrive at the scene of a fire;
  3. in multi-occupied premises, such as houses in multiple occupation (HMOs) and bedsits;
  4. extensions to existing properties, eg where it is planned to occupy what was originally roof space;
  5. in major refurbishment developments of social housing;
  6. as a trade-off for passive fire resistance in certain circumstances;
  7. sheltered housing;
  8. in residential care premises – in particular converted, older properties;
  9. housing for special needs and at-risk groups: the elderly and infirm, the physically disabled, people with a history of having fires.

Cost-benefit analysis

Brigades will need to be aware that justification for installing residential sprinklers may be required through a cost-benefit analysis. Issues to be considered may include highlighting the benefits to society of reducing the cost of ‘after care’ to fire victims provided by health authorities; reducing re-housing costs to local authorities for fire victims; reducing cost to the environment, etc.

Additional information can be obtained from the Residential Sprinkler Association.


Frequently asked questions

There are many misconceptions relating to sprinkler systems. Although no specific research has been done into the general public’s view of residential sprinklers, we know anecdotally that people are concerned about installing sprinklers in their homes.
Concerns range from sprinklers being an ugly addition to the home, to sprinklers malfunctioning and activating when there is not a fire. This section provides answers commonly asked questions on the use of sprinklers in a domestic environment.

Do sprinklers go off accidentally?
It is possible for a sprinkler to discharge accidentally but it rarely happens. In fact, if a sprinkler is not subjected to freezing, overheating, or mechanical damage, statistics from the USA suggest only 1 in 16,000,000 sprinklers per year will open accidentally.

What about water damage?
Concerns over water damage due to fires in sprinklered buildings are often exaggerated. The amount of water which is put on a fire by fire brigade hoses in an unsprinklered building is nearly always 10 times more than that which sprinklers would have discharged. It is also true that if the fire is not controlled in its early stages, then greater damage will be done by the fire and the extinguishing of the fire by the fire brigade. During a fire, only sprinkler(s) closest to the fire activate, limiting the total amount of water needed to suppress a fire.

Aren’t sprinklers ugly?
Owing to advances in sprinkler technology, sprinklers generally blend into the décor of a room. As with central heating, the pipes can be concealed behind ceilings, out of sight until needed to extinguish a fire. Sprinkler heads are also available in a range of colours and sizes.

Will special tanks and pumps be required?
Sprinklers are increasingly less demanding in terms of water flow. In most instances they operate from the domestic water supply and do not require any special water supplies or pumps. However, where water supplies are particularly poor, additional features such as water tanks and pumps may be necessary.

What about maintenance?
It has been argued that homeowners will be incapable of maintaining sprinklers to an acceptable standard and that pipes may burst in the winter if allowed to freeze. The same is true of domestic central heating systems, which are considerably more complex, and homeowners seem to be able to look after their pipes and have their boilers serviced.It is true that sprinklers are more at risk since they contain static water which is not ordinarily in use, so a frozen sprinkler pipe will be less likely to be discovered and more likely to burst. However, if a sprinkler system has been properly installed to the recognised standard for domestic sprinklers, with a built-in maintenance regime, it will be protected from freezing. But no system is fool-proof and risk-free and homeowners may need to be prepared to accept this slightly increased risk as a reasonable cost of improved fire safety.

What about installation?
The installation of a residential sprinkler system is arguably less complex than that of a conventional domestic plumbing system. A basic concept of sprinkler protection is that sprinklers must be installed throughout all areas of the building. Fitting a system to existing or new buildings can also be made easier by the use of PVC plastic piping.

How much does a sprinkler system cost?
The cost of a system is dependent on the size of the property and whether the system is installed during the construction stage or is retrospectively fitted. Generally a system for a new property would be 1-2% of the total build cost. To fit a sprinkler system to a house that is already built will cost a greater amount due to the difficulty of access for retro-fitting equipment.