A guide to passive fire protection: fundamentals and best practice

Perhaps Sir Walter Raleigh wasn’t directly referring to fire safety when he said that ‘Prevention is the daughter of intelligence’, but he certainly could have been. Whether it’s a small flat in a low-rise building or a huge shopping centre, people’s lives are at stake. Building owners and managers need to take both active and passive measures to ensure human safety in the event of a fire.

Grenfell Tower Inquiry Phase 2

The second phase of the Grenfell Tower Inquiry is scheduled to conclude at the beginning of 2022. The implications of the subsequent report will undoubtedly have a drastic impact on all building owners and managers across the U.K. Housing associations are, quite understandably, keen to understand how they will be affected.

While the exact ramifications are still unknown, it is clear that it will get tougher to meet compliance measures. Our current advice would be to do the basics well, such as carrying out a rigorous Fire Risk Assessment and writing a Fire Emergency Evacuation Plan. This will put you in a good position when the government passes new regulations—and make future compliance less costly.

What is passive fire protection (PFP)?

Like a vaccine, passive fire protection helps stop the spread of fire and reduces its severity. The term can include a wide range of products and practices, but it generally refers to materials built into structures that make them more fire-resistant.

The goal of employing PFP is twofold: to make a building safer for evacuation and, what’s even more significant, to prevent a fire from ever turning into a threat to life. 

Fire tends to spread from item to item and then from room to room. Certain products address the former, while intumescent materials address the latter. Regardless of what method is used, the fundamental goal of PFP is to delay or stop the spread of fire. 

What’s the difference between active and passive fire protection?

Active fire protection refers to equipment installed in buildings that start working when the equipment itself (or a person) detects a fire: a fire alarm, a sprinkler system, or a fire extinguisher, for example.

While all this equipment is essential, prevention is the best cure. It’s far better for a fire not to spread because a combination of passive measures has already stopped it.

But, of course, you don’t have to choose which method to use. A comprehensive fire protection plan will include both active and passive measures. Exactly which actions you choose depends on factors including the design, size, and purpose of the building and other considerations such as water availability in the area and the time established for evacuation.

Active fire protection is the first line of defence. And a plan to both defend and attack means people inside the building are as safe as possible.  

Why use a passive fire strategy?

Every building, no matter how large or small, should have an emergency fire strategy. A PFP is an integral component of that strategy as it is designed for three key reasons:

1. To limit the financial damage caused by the fire
2. To increase the time Fire and Rescue Services (FRS) have to evacuate a building
3. To save lives

And, it does this in three principal ways: 

1. By safeguarding the structure of the building 
2. By curbing the spread of fire and smoke
3. By protecting escape routes

How does passive fire protection work?

The pillar of passive fire protection lies in compartmentation. Walls, floors, and rooms are separated using different techniques (which we will discuss below) to divide the building into areas—or compartmentalised. This leads to improved safety for people inside buildings and gives them longer to evacuate.

The principles of passive fire protection

• Protecting escape routes by keeping safe waypoints
• Protecting building integrity
• Resisting heat conduction (insulation)
• Limiting the spread of fire, hot gases and smoke by containing it within a single zone or compartment

Load-bearing beams, walls, and floors have to be able to support their load under fire conditions. Doors, walls, glazed screens, and suspended ceilings have to stop fire ingress (flames and heat). Building services ducts need to be fire-stopped to ensure the ducting does not provide an easy route for fire. All fire resistance measures must be correctly designed, specified, installed, and maintained.

What are examples of passive fire protection products?

Fire doors

A fire door is fire-resistant or has a fire-protection rating. It reduces the spread of fire or smoke between rooms and acts as a protective barrier for people inside the building.

Fire dampers

Fire and smoke dampers are used in heating, ventilation, and air conditioning ducts to prevent the spread of fire inside the ductwork. They can sense if there is a temperature rise and automatically close. 

Firewalls

Firewalls are fire-resistant structures—usually made of concrete, concrete blocks, or reinforced concrete—designed to restrict fire spread through compartmentalisation. The key defining feature of firewalls is their structural independence. 

Coatings

Today, spray-applied epoxy intumescent and subliming are the most commonly used coatings. Other available types of coatings include phenolic foam, glass fibre, and elastomer rubber.

Additional products and systems

PFP products and systems can be installed in a building or be part of the fabric of a building. They should be installed by certified, competent parties and correctly maintained. Other examples include:

• Fire-resisting walls, floors, ceilings, and ducts
• Firestopping and fire protection for structural members
• Fire-resistant epoxy coatings that can be spray applied
• PFP sheets
• Fire-protective boxes or wardrobes
• Fire shutters
• Fire-resisting glazing
• Suspended ceilings
• Fire fighting shafts and stairwells
• Fire-resisting walls and partitions
• Fire-resisting ductwork
• Industrial fire shutters and curtains
• Linear gap seals
• Penetration seals for pipes, cables, and other services
• Cavity barriers
• Fire-resisting air transfer grilles (mechanical or intumescent)

What are fire protection best practices?

Firestopping

Firestopping is the sealing of any openings to prevent fire, smoke, and heat from passing through to different areas of buildings—either laterally or vertically. The building is made safer by creating fire resisting compartments.

Best practice should always be followed when a building is first designed and before its construction. If the building is extended or refurbished, firestops should also be included in the design.

BS 7671 is the national standard for electrical installations, and it requires any wiring systems to be correctly sealed to provide an efficient firestop. 

Fire Protection Surveys

The first step is to carry out a Fire Risk Assessment. You can either do this yourself or contract a professional fire safety consultant. Your Fire Protection Survey will use the findings to identify a plan of action to carry out in the building. It could include the following:

• Identifying equipment needed
• Making the escape routes clear
• Removing any potential hazards

Make sure to pay special attention to the type of people using the building—children, the elderly, or people with special needs, for example?

Whose responsibility is passive fire protection? 

In the U.K., the onus is on building owners, managers, occupiers, and designers to undertake regular fire risk assessments. These should include an evaluation of the PFP in the building and adhere to regulations, which state people must be able to safely exit a structure that will not collapse when on fire.

Regardless of whether the building is domestic or non-domestic, PFP provision is required in all buildings. In England, new builds, refurbishments, or extensions must adhere to The Building Regulations 2010, Fire Safety, Approved Document B. The regulation states that:

‘If a fire separating element is to be effective, every joint or imperfection of fit, or opening to allow services to pass through the element, should be adequately protected by sealing or fire stopping so that the fire resistance of the element is not impaired.’

What should a passive fire protection plan include?

A fire escape route

Key concept: People should have enough time to react to a fire and evacuate safely.

People’s ability to safely evacuate a building must be guaranteed. Due to external factors and confusion, people are likely to need more time to evacuate than might be thought sufficient. Regardless of what is happening in the rest of the building, the escape route must be able to resist fire for long periods.

Compartmentation

Key concept: Stop the fire from spreading throughout the building

It is easier for the FRS to fight a fire if it is contained within one area of a building. People are also more likely to be able to evacuate safely. Ensuring walls, ceilings, and floors can withstand the heat and installing some of the fire stopping products listed above will help the fire from spreading wildly throughout the whole building. 

Smoke extraction and ventilation ducts

Key concept: Remove smoke and slow down the fire from spreading

Toxic smoke inhalation kills more people than the fire itself. It reduces visibility, causing confusion and can lead to suffocation. Smoke also helps a fire to spread. For these reasons, a correct duct system to extract smoke is a crucial part of any passive fire protection plan. 

Structural protection

Key concept: Prevent the building from collapsing

When subjected to fire, a building’s structure can collapse. However, if the building’s load-bearing structure is safeguarded, it will be more able to withstand high temperatures. Fitting a building out with structural protection may also save the building after a fire. In addition, an efficient structural protection system will mean the building is more likely to be repaired rather than demolished. 

Conclusion 

Protecting people inside burning buildings is not easy. It requires the right mix of products, procedures, and systems. Getting it right depends on every building, as each one has its unique requirements based on size, shape, purpose, and materials used in construction. However, taking both active and passive measures will guarantee that every person stands a better chance of being safely evacuated from a building on fire.