The benefits of passive fire protection

Devising a firestopping strategy that can help contain and control the spread of fire is an essential part of most construction projects and one that can greatly benefit from collaboration with specialist product manufacturers. In this feature we look at how specifiers can take a more active approach to passive fire protection.

When you think about ways to protect a building from fire, chances are you may think of smoke alarms, fire blankets, extinguishers, sprinkler systems – all extremely important pieces of equipment but all examples of what is known as active fire protection. Put simply, these all require a degree of action or motion to work and are critical to alerting occupants to the outbreak of a fire and helping to extinguish it.

An important part of passive fire protection is firestopping and compartmentation. This can relate to a wide range of materials used within a building, such a fire doors and fire-resistant walls and flooring but also specialist products that help restore the fire resistance of walls and floors disrupted by linear seals, cavity barriers or penetration services. Such passive fire protection is designed to ‘activate’ once a fire has already taken hold and is essential for helping to contain and control it within defined compartments. Not only is passive fire protection important in reducing the potential damage a fire can cause to a building but, above all, it can help save lives by preventing fire spreading to increase the time that people can be safely evacuated.

Contain and control

Unlike active fire protection, some of the most effective firestopping or passive fire protection products are those that building occupants may not even be aware of. However, just because they can’t be seen doesn’t mean that they aren’t an integral part of the building fabric. In fact, passive fire protection is required in nearly all public use buildings across the hotel, leisure, healthcare and education sectors, as well as in residential and commercial high-rise buildings, transport infrastructure such as airports, large-scale shopping centres and industrial facilities. 

Most buildings like these are naturally interspersed with multiple utility and network services such as cables, cable trays, pipes and ventilation ducts, and this results in countless penetrations through which flames, smoke and heat can quickly spread. To protect adjoining rooms and areas and to prevent further fire propagation throughout the entire building, it’s essential that measures are taken to stop fire in its tracks. This is where specialist products such as silicone sealants, acrylic sealants, PU foams, fire boards, pipe collars, load-bearing compounds, pipe wraps, and backer rods should be considered. 

Where to start with firestopping systems

In terms of compartmentalising fire, the potential ‘weak spots’ in a building fall into three key categories: linear joint seals, cavity barriers and penetration seals.

Linear joint seals can be found in walls, floors and in so called ‘head of wall applications’, which are the joints between a wall and ceiling or a wall and floor.

Linear joint seals are passive fire protection systems designed to maintain the required building fire resistance across a separating element, whilst also being able to accommodate a defined degree of structural movement.

Cavity barriers are passive fire protection systems which are similar to linear seals but are, in most cases, wider than standard joints. Typically, cavity barriers can be found between floor slabs and curtain wall facades or in wide gaps within a building. Such cavity barriers are designed to avoid the spread of fire from one floor to the other, which is one of the major threats when high-rise buildings catch fire.

Service penetration seals are passive fire protection systems designed to maintain the fire resistance of a building element or section, either a wall or floor, where services such as cables, cable trays, pipes or ventilation ducts pass through them. One of the key challenges of sealing around penetrations is that certain services (e.g. combustible pipes) will melt in the event of a fire, which results in even larger openings that must be closed immediately. For this type of application, expanding intumescent materials are usually a very effective solution.

Fire reaction and resistance 

As well as being aware of the areas within a building which can benefit from passive fire solutions, it’s important to understand what level of protection is required and what the different ratings and standards mean. It’s also vital that specifiers and specialist passive fire protection product manufacturers can work together to make sure that the correct firestopping products are used in the correct place, and in the correct way.

Fire testing is, quite rightly, a very complex process that is difficult to summarise but there are a number of frequently used terms that specifiers should be familiar with. It’s particularly important to understand the difference between ‘reaction to fire’ and ‘resistance to fire’.

‘Reaction to fire’ describes how a material contributes to the development and spread of a fire. Typically, reaction to fire is determined for a single material or product such as a wall covering or joint sealant, and not for a system or section, such as a wall including the linear joints and any penetrations. Reaction to fire can be determined according to various standards but EN 1366 is the most relevant in Europe and can be considered as the baseline.

‘Resistance to fire’ considers the ability of a building element to prevent the passage of heat and flames from one side to another. Typically, such building elements are walls or floors including any joints and penetrations such as windows and doors. This means that it’s not only a specific material or product but an entire system or building section that has to be tested.

Fire resistance is tested in relation to a building element’s level of integrity (referred to in tests by the letter E) and insulation (similarly, referred to by the letter I). Integrity focuses on the building element’s capability, when exposed to fire on one side, to prevent the passage of flames and hot gases to the unexposed side. Insulation looks at how well the building element can limit the amount of heat transference when exposed to fire on one side. Fire resistance is therefore based on the time it takes for either heat, smoke or fire to compromise the integrity and insulation of a system and this is often shown in minutes from 15 to 240.

Technical support

Many factors can influence the fire resistance and classification of a building element, and many buildings will require a bespoke passive fire protection strategy. This is why supply chain collaboration is so important so that specifiers can tap into the expertise of manufacturers. 

At Sika, we can provide detailed technical evaluations to assist with the correct specification of passive fire protection products for linear joints and seals, cavity barriers and penetration seals. Here we would consider factors such as the building materials involved (concrete, steel etc.), orientation (walls or floors), the thickness of the element, the joint dimensions (width and depth), the joint configuration (single seal exposed, unexposed, double seal etc.) and expected joint movement. 

We understand the importance of protecting all buildings from the devastating effects of fire and ensuring the safety of all building users, which is exactly why our offering extends much further than just our products. We have also invested heavily in the training of our technical team so that we are qualified to advise and assist our clients in devising and implementing a robust passive fire protection strategy. 

For more information, go to www.sika.co.uk/passivefire