What is fire compartmentation?
Fire compartmentation is a built-in fire safety strategy that divides a building into separate fire-resistant compartments to prevent the uncontrolled spread of fire and smoke. Each compartment is designed and constructed to resist a fire for a given period.
The aim is to stop a fire engulfing an entire dwelling within a very short time. By isolating distinct sections of a building, compartmentation slows the spread of fire and smoke, allowing residents time to evacuate and giving the fire services a window to put the fire out.
Compartmentation is one part of a wider fire safety system. It works alongside fire detection and alarm systems, emergency procedures and fire escapes.
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What is a fire rating?
A fire rating states how long a fire compartment will keep performing its function under fire conditions, usually in minutes. It describes the compartment's resistance to fire penetrating it and its ability to contain a fire within its boundaries.
The rating allocated depends on factors such as the type of construction, the materials used and how critical the compartment is.
What does Approved Document B require?
Approved Document B, also known as fire safety, is the building regulations guidance in England focused on fire safety. It sets out the provisions to follow when designing buildings, to lessen the risk of fire-related incidents and provide effective means of escape.
It applies to new construction, alterations and extensions for residential, commercial and mixed-use buildings, and covers the technical measures needed for adequate fire safety, including compartmentation.
Fire resistance between dwellings and common areas
There needs to be substantial fire resistance between a dwelling and the common parts such as stairways or lobbies. The fire resistance required depends on the type of building.
This provision is intended to give occupants a high chance of escaping before fire breaches the compartment.
Which regulations and standards cover compartmentation?
In the UK, British Standard 9999, British Standard 9991 and Approved Document B set out guidance on fire compartmentation. By regulating and standardising fire-resistant materials and compartmentation strategies, they bring uniformity and predictability to fire safety measures.
Who is responsible for fire compartmentation?
Under the building regulations, responsibility predominantly lies with the building owner or the person carrying out the work.
Contractors and architects implement the measures during construction or renovation, but the ultimate responsibility rests with the building owner. Homeowners, landlords and property managers should therefore check that appropriate fire safety measures are in place and maintained.
What are the risks of poor compartmentation?
A dwelling without appropriate compartmentation can suffer catastrophic outcomes in a fire.
- Fire spreads swiftly, endangering lives.
- Significant damage is caused to the property.
- In severe cases, neighbouring buildings can be affected.
What to do next if compartmentation is inadequate
- Engage specialists to identify the fire safety shortcomings.
- Reinstate fire-stopping, the sealing of gaps and openings that would let fire pass between compartments, as Approved Document B suggests.
- Incorporate fire doors where necessary.
- Have the work rectified to the mandated standards.
- Keep fire doors and escape routes regularly inspected, and repair any damage promptly.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition of a property. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
When buying a property, a building survey can highlight fire safety shortcomings, including visible breaches in fire compartmentation that could prove disastrous in a fire.
- Visible breaches or gaps in fire-separating walls and floors.
- The presence and visible condition of fire doors.
- The visible condition of escape routes and common parts such as stairways and lobbies.
However, there are limitations to what a survey can determine without intrusive investigation.
- The actual fire rating of walls, floors and doors.
- Fire-stopping hidden within walls, floors and ceiling voids.
- Whether the building meets the full requirements of a fire risk assessment.
Where higher-risk indicators are identified, further specialist or intrusive investigation may be recommended.
Frequently asked questions
What is compartmentation in a house?
It is the division of a building into areas, or compartments, separated by fire-resistant walls and floors to prevent the rapid spread of fire.
How is fire resistance measured?
By a fire rating, usually in minutes, stating how long a compartment will keep resisting fire penetration and containing a fire. The rating depends on the construction, the materials and how critical the compartment is.
What is Approved Document B?
It is the building regulations guidance in England on fire safety, setting out provisions for design, compartmentation and means of escape in new buildings, alterations and extensions.
Who is responsible for fire compartmentation?
Predominantly the building owner or the person carrying out the work. Contractors and architects implement the measures, but ultimate responsibility rests with the building owner.
How is poor compartmentation put right?
Typically by reinstating fire-stopping and fitting fire doors where necessary, with specialists engaged to identify shortcomings and rectify them to the mandated standards.
