Everything you need to know about fire compartmentation

Effective compartmentation is integral to any passive fire protection strategy. It should be incorporated into a construction project as early as possible so that buildings remain structurally sound in the event of a fire. Compartmentation is also crucial for compliance with fire protection regulations and industry standards. This article will introduce you to the main principles of compartmentation, as well as some of the rules and requirements that establish best practice.

What is compartmentation in fire safety?

Simply put, compartmentation is the process of dividing a structure into ‘compartments’ for effective risk management. Each compartment is reinforced by using fire-resistant materials and by installing protective measures such as fire doors or cavity barriers. By dividing buildings into fire-resistant compartments, it is more likely that a fire can be effectively contained and suppressed.

The official definition, found in Approved Document B, states that compartmentation is: “A building or part of a building comprising one or more rooms, spaces or storeys constructed to prevent the spread of fire to or from another part of the same building or an adjoining building.”

Where can you find fire compartmentation systems?

Walls and ceilings

Each wall and ceiling that defines a compartment must be reinforced using fire-resistant materials. That could mean using cavity barriers in voids between walls and floors, or detecting and remediating non-compliant service penetrations which could result in gaps that enable the passage of flames or smoke. Not only must these gaps be sealed, but walls and floors should ideally be insulated to prevent the spread of fire through heat transference.

HVAC systems

HVAC systems form an interconnected infrastructure throughout a building, which means they can also enable the spread of fire if not adequately protected. HVAC systems should be fitted with fire dampers that immediately close when exposed to heat, and appropriate fire stopping solutions should be applied to pipes and ducts. You can find out more about this in our guide to fire stopping for pipes.

The materials used in fire stopping are highly specialised, and the choice of materials used is dependent on the context of the building itself. They include fire-resistant board systems, intumescent materials that swell to fill cavities when exposed to heat, and fire collars that prevent pipes from becoming a weakness in the compartmentation system.

What is the main objective of fire compartmentation?

As mentioned throughout this article, the main objective of compartmentation is to contain a fire within a specific section of a building. This allows more time for occupants to safely evacuate a building and for fire services to extinguish the flames.

Whilst safety is always of paramount importance, another common objective of fire compartmentation is to prevent a fire from reaching parts of a building that are of particular value or contain hazardous materials. Common examples include modular plant rooms in industrial buildings or server rooms in commercial premises.

Fire evacuation procedures can vary based on a building’s purpose, size and any specific risks. For instance, buildings may utilise a ‘defend in place’ strategy, which looks to minimise the number of people required to evacuate a building. This strategy is often used in healthcare facilities, where staff may find it virtually impossible to evacuate highly vulnerable patients.

CLM Fireproofing has provided fully-compliant compartmentation for construction projects across the UK. A great example of this is One Crown Place, an exciting Hackney-based construction project. Take a look at our case study to find out more and contact CLM Fireproofing if you have any questions.

Fire compartmentation requirements

The most relevant and up-to-date compartmentation regulations can be found in Approved Document B. This document covers all regulatory matters relating to fire safety in and around buildings. To give you an indication of what the document covers about compartmentation (in non-residential buildings), we’ve listed some of the main points below:

• The minimum period of fire resistance for a compartment wall or floor can vary based on a building’s specific purpose as well as the presence of sprinkler systems. A comprehensive overview of minimum fire resistance periods can be found here.
• When a building is over 30m in height, each storey must be separated by a fully-compliant compartment floor.
• Any wall that is common to two or more buildings should be constructed as a compartment wall. These should extend to the full height of a building in a ‘continuous vertical plane.’
• Compartment walls should ideally be used to separate areas of a building that serve different purposes (e.g. storage or commercial operations).
• If a compartment wall is installed between two adjoining buildings, the only permitted openings are for fully-compliant fire doors and pipes. It is imperative that these pipes are appropriately firestopped, regardless of their diameter.
• While compartments should ideally be completely separated, there may be instances where they are connected by beams, joists or rafters. If so, any openings caused by these structural elements must be appropriately firestopped.
• Construction teams may look to install fire-resistant ceilings and cavity barriers as part of a compartmentation strategy. If so, these must be able to hold their structural integrity for a minimum of 30 minutes in the event of a fire.

Of course, specific requirements can be required above and beyond this, depending on the type of building and the presence of hazardous materials. With so many variables to consider, the interpretation of building regulations dealing with compartmentation requires specialist expertise.

There are compartmentation regulations covering everything from dwelling houses to flats and non-residential buildings. In every instance, the time frame during which compartmentation should contain fires is specified. This is usually 30 to 60 minutes. Despite the varied requirements for different types of buildings, the main objectives of compartmentation remain the same: containing the spread of fire to protect life, including the lives of firefighters, and property.

Who is responsible for ensuring that compartmentation is compliant?

In the wake of the Grenfell Tower fire, passive fire protection regulations have been scrutinised and revised at length. Accountability must now be assigned to a “responsible person” who will ensure that fire safety surveys are conducted by a competent person at regular intervals.

Following fire risk surveys, managers and landlords must prioritise any maintenance and repair works needed to maintain effective compartmentation. The responsible person (usually the building’s owner or manager) must keep detailed records of fire protection interventions in adherence to the ‘golden thread’ standards. This makes the information available to their successors and to the occupants of the building should they wish to review it.

This assignment of accountability makes passive fire protection, including the maintenance of effective compartmentation, an important part of the legal compliance duties of building owners and managers. If a fire should lead to fatalities, injuries, or property damage and there is evidence of negligence, courts may impose severe penalties.

Managing risks in compartmentation

Like any fire protection system, compartment walls and floors must be regularly monitored and maintained if they are to remain effective. This article has already delved into the risks of service penetrations, but another crucial risk in compartmentation relates to fire door maintenance.

Fire doors can also be considered part of a compartmentation strategy. However, they are often subject to either misuse or neglect. One of the most common examples is fire doors being wedged open to ensure easy access. This can cause what is referred to as the ‘chimney effect’, which is when the spread of fire is exacerbated by air moving in and out of a building.

It was estimated in 2018 that 64% of buildings visited by fire services had a fire door wedged open. Therefore, while a building’s occupants must be warned about the risks associated with misuse, property owners and commercial landlords must invest in regular fire door inspections and maintenance.

Fire risk assessments help building owners to mitigate risk, and should be carried out at intervals that may vary depending on the type of building, and the way it is used. If major alterations to the building are undertaken, involve fireproofing specialists so that compartmentation systems continue to comply with regulations.

CLM Fireproofing is the UK’s leading provider of passive fire protection services, including compartmentation. Working with clients across many different industries, we ensure that buildings (both residential and non-residential) are fully compliant with the latest fire protection regulations. If you’d like to know more about our services, please contact us today.