Fire Resistant Boards – Constructing Safer Buildings

Promat 04/11/2018

fire board
fire resistant board
fire resistance

Fire Resistant Boards: Stopping The Fire and The Heat From Spreading

Whenever a fire develops in a building, it is important that the fire stays where it is and that load-bearing structure remain in place for a time sufficient for people evacuation and rescue operations.

fire protection solutions using fire resistant boards
fire protection solutions using fire resistant boards

Fire resistant boards are designed to do just that: they are resistant against the heat and radiation of the fire. Thanks to their low conductivity and high heat absorption, combined with low shrinkage to keep their integrity, they make sure that on the other side of the board the temperatures remain low during a long period of time.

Thanks to these capabilities, a fire resistant board can be used for many applications, including the fire barriers for:

  • compartmentation of buildings
  • encasements or secondary linings for protection of the building's loadbearing structure
  • encasement of electrical cables
  • ventilation and smoke extraction ducts

In all these applications, the fire board fulfills the same function. On one side of the board there is the heat of a raging fire, on the other side the temperature remains low. 

By keeping the fire and heat locked up behind fire resistant boards, the fire does not propagate through the building and doesn’t increase too much the temperature on loadbearing structures. People have time to escape to a safe place, fire and rescue services can intervene, the building structure does not collapse, hot smoke can be extracted (essential to the safety of people) and safety-critical systems inside the building keep functioning.

  • R: Loadbearing function – ability of a structure to carry the loads without collapsing.
  • E: Integrity – ability to stop flames and hot gases from penetrating.
  • I: Insulation – ability to restrict the temperature rise on the cold side. In most cases, the temperature at the cold surface may not increase more than 140°C on average, or 180°C locally in case of local variations.

The fire resistance is always expressed in minutes, usually in classes that are multiples of 30 minutes. For example a fire protected steel structure that can withstand fire during at least 120 minutes will be “R120”, and a partition wall that keeps the flames out and temperatures low during at least 120 minutes will be “EI120”.


Reaction to Fire

If a material burns, it can contribute to the fire development. The behaviour of material when exposed to heat is called the reaction to fire, and is expressed in classes such as A1, A2, B, C etc. Class A1 and A2 are considered as non-combustible materials. Most Promat fire boards are non-combustible “A1”, which is the best (safest) possible classification.

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Types of Fire Resistant Boards

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There are many different types of fire resistant boards, with different production technologies and compositions. Some boards rely more on thermal insulation values, some boards more on heat absorption, but in the end they all aim to maximise the temperature reduction on the cold side compared to the fire side.

However thermal performance is not all that counts. Each type of board has its own behavior during fire. For example shrinkage, cracking or deformation while exposed to fire can reduce the effectiveness of a board. Promat boards are characterized by a high thermal stability, so they deliver fire resistance under the most severe conditions.

Within the Promat board range, different board types and a wide range of board thicknesses are available, each suited for specific fire safety applications. Apart from the fire resistance performance, the different board types each have specific advantages such as easy installation, resistance against impact or resistance against weather exposure.


Fire Resistant Boards - Always Part of a System

A fire resistant board alone cannot stop the fire. For the board to perform, it must be held in place with the correct types and distances of fixings, and the different boards need to be correctly joined so flames do not penetrate through any gaps. If a board shrinks or deforms more, more complex solutions are needed for the fixings and joints, such as mounting clips, metal substructures, joint fillers. This will show in the test reports and installation instructions of the board. If mounting instructions are not carefully followed, for example omitting or not carefully applying a required joint filler, using the wrong type of fixing or a fixing distance larger than allowed, the fire resistance will be drastically reduced.

As Promat boards are optimized for thermal stability and mechanical strength, in most cases the boards can be simply put in place and fixed with staples or screws, and no joint treatment is necessary. A stable board enables a simple system, which will be more reliable because it leaves little room for mistakes during the mounting. An additional benefit is obvious: a simple installation method saves time and costs.

The Fire Resistance Performance Depends on the System

The fire resistance performance is a characteristic of the system, not of the board alone. During a fire test the performance depends on a complex interaction of temperature flows and shrinkage and deformations. Therefore a fire resistance classification always needs to be based on test results for the given application, board type, thickness and installation method. The possibility to extend the scope by calculations is limited, because the complex behaviour during fire is hard to capture in models, and extrapolation of test results is generally not allowed.

Therefore when looking at fire resistant board solutions, being it a partitioning wall, structural protection, cable encasement or smoke ducts, always consider the system and not only the board, and rely on fire resistance classifications that have been determined by independent institutes.

Other Performances of the Fire Resistant Boards

We all hope that there will be no fire and therefore the board also has to perform well on other aspects. The board must be durable to resist relevant exposures during its working life in a building. For example exposure to heat, cold, moisture, direct or indirect weather exposure or mechanical impact can pose specific requirements to a board. This is where different board types have specific strengths. Relevant durability classification is done according to European Assessment Document 350142-0-1106 (previously ETAG 018-4). Most of Promat boards are classified for a durability of 25 years (the best possible result) for internal application and, in some cases, even for semi exposed application.

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Need help for your project?

contact Promat technical support

Considering the relevant fire requirements, board types and details of installation methods and other aspects such as durability, mechanical resistance, acoustics etc. is complex.

Please contact our technical department to help you choose the type of fire protective board or complete system fitting needs of your project and assuring about the realised fire safety level according to fire regulations.