What structural measures can prevent the spread of fire?

Construction projects, be they commercial or residential, must involve fire protection specialists from the outset. They can advise on what structural measures are required to prevent the spread of fire.

Investigators into the Grenfell Tower fire revealed multiple structural failures. Upon review, the building’s cladding was found to have a range of flaws. According to fire safety engineer Barbara Lane, this created “multiple catastrophic fire-spread routes.” This reinforces the fact that it takes more than alarms or sprinklers for a building to be protected.

What do we mean by structural measures?

The term ‘structural measures’ defines the ways in which fire protection is incorporated into the construction of a building. If a fire were to occur, they ensure a building preserves its structural integrity for as long as possible.

The main purpose of structural fire protection is to prevent fire and smoke from spreading throughout the building. This helps to contain the damage, and ensure there is an ample window for the building’s inhabitants to be safely evacuated. The Building Regulations for England and Wales have provided guidelines for how long a building must maintain its structural stability in the event of a fire:

• A building less than 5 metres tall must remain stable for 30 minutes
• A building between 6 and 18 metres tall must remain stable for 60 minutes
• A building between 19 and 30 metres tall must remain stable for 90 minutes

This article will outline several structural measures that can stop a building from being fully consumed by fire. When implemented correctly, these measures can save lives and reduce financial losses.

Intumescent Coatings

In the event of a fire, steel will lose its load-bearing properties once it reaches a certain temperature (this can vary between 350° and 750°). Therefore, steel structures must be insulated using an intumescent coating. This increases the amount of time before the steel collapses, giving firefighters more time to evacuate a building.

When exposed to temperatures of up to 250°C, multiple chemical components inside the intumescent coating will react. This causes the coating to increase in density, creating a fireproof layer to protect the steel. These intumescent coatings can be applied in a variety of ways, from thin filming coatings to spray-applied paint.

Intumescent coatings are easy to apply both on and off-site. They are also suitable for not only steel but concrete, timber, and composite elements. As well as this, applying an intumescent coating doesn’t affect the material’s mechanical properties. This means that the coating is essentially ‘neutral’ unless exposed to extreme temperatures. This makes intumescent coatings both an efficient and effective fire protection measure.

Compartmentation

Compartmentation involves dividing a building into a series of ‘cells’. These cells are then separated using fire-resistant materials and structures. Fire can quickly engulf a building due in part to the ‘chimney effect’. This is when the airflow between floors and rooms ‘pushes’ flames throughout a structure. Compartmentation reduces this effect, containing the flames and smoke to a specific cell.

There are multiple ways to compartmentalise a building, such as fire walls, doors, and cavity barriers. Cavity barriers inhibit the spread of smoke through open spaces in roofs and between floors. These barriers can be made from a variety of materials, such as concrete, gypsum or masonry.

There is no doubt that in principle, compartmentation is an effective way to hinder the spread of fire. However, there are times when compartments can be breached due to building maintenance. This leads to our next structural fire protection measure.

Firestopping

Sometimes when plumbers, electricians, and contractors work on a building, they can inadvertently compromise structural fire protection measures. Say an electrician drills holes and runs wires through a fire wall. No matter how small this hole may be, the wall no longer offers effective fire protection. Fire can penetrate the smallest gaps and ignite almost anything that lies in its path. Therefore, these gaps must be filled as quickly as possible. This process is called ‘fireproofing.’

Successful fireproofing requires the use of specific fire-resistant materials. Any breaches in fire compartments must be filled using an intumescent sealant. when exposed to high temperatures. This fills any gaps and prevents the passage of smoke and flames.

Any openings between compartments, such as doors, windows, joints, pipes, and ducts, must be fireproofed. It is vital that in the event of a fire, there is no opportunity for fire to break through a compartment.

Construction professionals must realise that it takes more than investing in structural measures. Firstly, these measures must be implemented in compliance with industry regulations. Secondly, they must be reviewed regularly, with any breaches or material degradation swiftly rectified.