What Is Fire Load, and Why Should You Care?

When assessing fire risk in a building, most people think about alarms, extinguishers, or escape routes. But one of the most critical, and often overlooked, factors is fire load.

If you’re responsible for fire safety in a building, whether as a business owner, landlord, or facilities manager, understanding fire load can make all the difference between a routine fire and a rapidly escalating disaster.

What Is Fire Load?

Fire load refers to the total amount of combustible material in a space, expressed in terms of the amount of heat it would release if it all burned. It’s usually measured in megajoules per square metre (MJ/m²).

It includes:

• Furniture and fixtures (desks, chairs, shelving)

• Packaging and stored goods

• Electrical equipment

• Paper, textiles, plastics, and wood

• Flammable liquids or chemicals (where applicable)

In simpler terms, fire load is a measure of how much fuel a fire has to burn in a given area.

Why Does Fire Load Matter?

The greater the fire load, the:

• Hotter the fire can get

• Faster it may spread

• Longer it may burn

• Harder it is to control or extinguish

These factors directly influence how you design a fire protection strategy. A high fire load demands:

• More advanced detection systems

• Higher-rated fire-resistant walls or compartmentation

• Specific suppression systems (e.g. sprinklers)

• Adjusted evacuation strategies and times

 

Examples of Fire Load in Different Settings

Even two identical-looking spaces can have wildly different fire loads depending on what’s inside them. That’s why fire load is a crucial factor in site-specific fire risk assessments.

How Is Fire Load Calculated?

Fire load is calculated by:

1. Listing all combustible materials in the area

2. Determining their calorific value (how much heat each material gives off)

3. Multiplying that by the quantity and density

4. Dividing by the floor area to express in MJ/m²

While exact calculations are usually carried out by fire engineers or qualified assessors, knowing the concept helps you understand the reasoning behind certain fire safety measures.

Fire Load and the Law in the UK

Under the Regulatory Reform (Fire Safety) Order 2005, the Responsible Person must take general fire precautions “to the extent that it is reasonable and practicable.” That includes considering how easily a fire could start and spread, and that’s where fire load plays a key role.

The Fire Risk Assessment must consider fire load when:

• Evaluating escape times

• Selecting fire-resisting construction

• Specifying suppression systems (e.g. sprinklers or gaseous systems)

• Deciding compartment sizes and wall ratings

• Assessing emergency lighting and signage needs

If you fail to account for high fire loads, your fire strategy may not be robust enough to protect life or meet legal compliance.

Reducing Fire Load: Practical Steps

While not every fire load risk can be eliminated, here are steps to reduce it:

• Declutter storage areas regularly

• Use fire-retardant furnishings where possible

• Store flammable liquids in approved cabinets

• Keep paper stock away from ignition sources

• Avoid unnecessary accumulation of packaging materials

• Limit the use of large quantities of plastics or foam materials in display or seating areas

 

Fire Load Isn’t Just Technical, It’s Life-Saving

Fire load might sound like a technical term, but it’s a key driver behind how fast a fire spreads and how severe the damage can be. Understanding it allows you to make better decisions during your fire risk assessments and ensures the safety systems you have in place are fit for purpose.

If your building has a particularly high fire load, it’s worth speaking with a fire safety professional to review your evacuation times, fire resistance levels, and whether you may need enhanced detection or suppression systems.

For expert advice on fire protection and prevention measures, contact Martyn Young Fireproofing Consultancy on 07585 896648