FIRE RESISTANT BOARDS, AN ULTIMATE GUIDE*
When fire develops in a building, it is important that the fire stays where it is. In fact, fire reminds us that it is important to distinguish between the right materials. Fire retardants such as calcium silicate boards are designed to slow down the spread of fire. Those fire boards are used in construction projects to meet fire safety standards and codes. They reduce the burning rate as a result, and prevent flames from spreading. Depending on the manufacturer and chemical composition, they appear under many names such as Monolux 500/800, Masterboard, Supalux, Promat PROMATECT L500, Cembrit FR, Y-wall, Glasroc F, Magply, STS, Densglass or Knauf fire panel. To make things more complicated, fire-rated boards are also called: calcium silicate board, non-combustible board, fire-resistant plasterboard, fireproof board, fire board, fire-retardant, pink plasterboard and so on.
There are many different types of fire protective boards here in the UK, with different production technologies and compositions. Some boards rely more on thermal insulation values, and some more on heat absorption, but in the end they all aim to maximise the temperature reduction on the cold side compared to the fireside. Some boards are lighter and easier to cut when others don't offer "score and snap' cutting technique. While manufacturers create boards with different properties, all of them have one thing in common. They are designed to save lives by increasing fire protection for drylining, wall lining & ceiling systems.
In this article, we will be reviewing the specific fire resisting properties of common building fireproof boards. You will find out which manufacturer offers the best fire board and which one offers the best performance.
TABLE OF CONTENTS
FIRE RESISTANT BOARDS, AN ULTIMATE GUIDE
FIRE BOARDS THERMAL CONDUCTIVITY
FIRE BOARDS MANUFACTURERS | PRODUCTS
FIRE RESISTANCE REI MARKING | 15 | 20 | 30 | 40 | 60 | 90 | 120 | 180 | 240 | 360 | MIN
FIRE BOARDS DETAILS
Fire resistant boards are engineered products designed to help inhibit fire spread by doing just that: 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 load bearing structures. The protection panels are also designed to withstand wet and humid conditions as well, in which the boards can be installed during the early stages of the construction.
Fire board is suitable for drylining, wall lining, shafts and partitions. They can be used either in the construction of electrical and mechanical ductwork enclosures, fire rated bulkheads, walls or ceilings where space is limited. Boards are suitable for a variety of applications offering from 30 up to 240 minutes fire resistance and supplied in the most common UK sizes: 2400x1200mm (8x4) and 2440mm x 1220mm. Common thicknesses available on the UK market are: 6mm, 9mm, 12mm, 12.7mm or 15mm. Fireproof boards are lightweight and can be processed with traditional wood tools. They can be cut, drilled and ground, which greatly facilitates the construction process.
FIRE BOARDS TIMING
When choosing fire boards, their most important feature to consider would be the ability to stop the fire as long as possible. These boards come in many types and grades and offer variable degrees of safety from fire: some types can resist fire for 60 minutes while others can resist fire for 240 minutes. The fire resistance is always expressed in minutes, usually in classes that are multiples of 30 minutes. Simply, this means how elements either in combination or individually stop a fire spreading, how they resist temperature rise and how the element's load-bearing capacity is maintained.
Before you choose your fire board, it’s important to choose the board with the highest number expressed in minutes. By looking at the above table you can distinguish products such as Supalux, Monolux-500, Monolux-800, Promat Promafour. Those boards guarantee the longest time needed for evacuation. We all know that in the case of fire, every minute counts. The shortest time is offered by Promat Masterboard, Glasroc F and Knauf fire panel. Factors that play a key role in this material could include the composition of the core material and water contained in it, as well as density and shrinkage. Generally speaking gypsum based boards can provide up to 120min of fire resistance protection for building assemblies and calcium silicate boards up to 240min.
WHY TIMING IS SO IMPORTANT?
The speed at which occupants of a building can evacuate in the event of a fire is critical.
FIRE BOARDS DENSITY
There are other characteristics of the fire resistant material that also play an important role in determining the time during which the boards are able to provide some level of fire protection. Perhaps the most important characteristic is density (mechanical properties). The board density can provide a first level approximation of the available water mass contained within the boards. Lowest density boards from manufacturers effectively represent the lowest likely performing boards that are available in the UK. Although board density is only one of the parameters, it is probably the key parameter that dictates the delay in the failure of the fire board when subjected to a fire source. It is therefore critical to ensure that minimally compliant material is used in establishing generic complying assemblies for regulatory purposes.
Here, the best performance is achieved by STS, RCM Multipurpose, RCM Y-wall and Cembrit FR. Their minimum density is 1050kg/m3. Compared to the density of the Glasroc F or RCM Densglass (725kg/m3) it seems to be 25% more. Looking overall at the density values for all of the board types and manufacturers (table), it is clear that the density of the regular gypsum based board is substantially below 850kg/m3. This type of board demonstrates anywhere between 75% to 80% of the density of an equivalent calcium-silicate board.
FIRE BOARDS CUTTING
Fire rated boards are made from a mixture of fibers and chemicals like calcium carbonate that don’t catch fire, adding to the safety of a building. If you are about to fit your home or workplace with fire boards, you will need to know how to cut them in order to fit them. This is where our table above comes in handy. It turns out that not all fireproof boards can be cut with manual tools or the ‘score & snap’ method itself. There is a simple rule here - the more dense the boards are, the more complicated they are to cut. While some boards such as Glasroc F, Magply, Promat Masterboard or Knauf fire panel can be cut with scoring & snapping technique, others can only be cut with power tools like circular saw or jigsaw (Promat Supalux, Cembrit FR, RCM Y-Wall, Promat Monolux 500/800). Cutting may not be an important detail, but it determines the installation speed at the end of the day.
FIRE BOARDS THICKNESSES
Fireboard is a fire panel available in a wide range of thicknesses. The length of time that the fireboard can retard the fire will vary depending on thickness, but ultimately, the overall construction and materials of the building is what determines overall fire rating.
Fireboard is most commonly found in 12mm and 15mm thicknesses. There are companies such as Promat that offer additional thicknesses such as 19.1mm, 25.4mm, 31.8mm, 38.1mm or 50.8mm. There is a direct correlation between the fireboard thicknesses and the amount of them that they will retard the fire.
The thicker the board the more time the fireboard will hold up and not deteriorate in the event of a fire. For instance, a 15mm fireboard will last for up to 60min, 12mm will last 45 minutes, 9mm will last one half an hour, and so on. Remember, if there is a hole in the board to allow for wiring, this will eliminate the protection that the fireboard provides. When used in a partition or ceiling, two layers of 12.5mm fire plasterboard should provide up to one hour’s fire protection. In a partition where there are two layers of fire-rated plasterboard on either side, they will provide up to two hours of fire resistance.
FIRE BOARDS COMPOSITION
Fire rated boards slow the spread of a fire in two different ways. Firstly, a fireboard contains a higher concentration of water in its composition, so that in the event of a fire, the higher concentration of water in the material makeup of the board works, in effect, as a miniature sprinkler system.
Secondly, a fireboard has special fibers in its material makeup that helps to maintain the barrier longer in a fire, keeping the fire from spreading from one area of a home or building to another. Generally speaking, all calcium silicate boards when compared to gypsum base panels tend to hold fire for longer.
FIRE BOARDS THERMAL CONDUCTIVITY
In addition to flame retardant properties, thermal conductivity plays an important role when choosing a fire board. Thermal conductivity refers to the intrinsic ability of a material to transfer or conduct heat. The lower the thermal conductivity of a material, the better the thermal performance. On the other hand, materials with a higher thermal conductivity are good conductors of thermal energy.
Some fire boards will have different thermal conductivity values. For instance, best fire board in terms of thermal conductivity would be Promat Supalux (0.17W/mK), Promat Monolux (0.18W/mK), RCM Multipurpose (0.17W/mK) and Magply (0.19 W/mK). For comparison, Glasroc F offers 0.30W/mK, Cembrit FR 0.25W/mK and RCM Siltech 0.25W/mK.
FIRE BOARDS MANUFACTURERS | PRODUCTS
Fire protection boards are manufactured by leading brands and are suitable for use in any project where additional fire proofing measures might need to be taken. In terms of fire protection boards, Promat, Kemwell, British Gypsum, Rockwool, Vitcas and Knauf are the commonly recognised brands. There are three main manufacturers of fire-rated plasterboard in the UK; Knauf Drywall, British Gypsum and Siniat. These manufacturers have an excellent fire protection reputation. Knauf Fire Panel is a good value and reliable fire plasterboard to go with. Knauf Fire Panel is a high-quality gypsum based plasterboard with additives for fire performance that is suitable for Fire-Rated partitions and any other drylining application where fire rating is crucial.
MASTERBOARD
Masterboard is made by Promat and it is a Class O building board with limited combustibility providing up to 30 minutes fire protection. This board is also suitable for external use in semi-exposed applications, whilst adding its fire rating qualities.
SUPALUX
Supalux, made by Promat, is Class O fire rated for surface spread of flame as well as being a non-combustible, high performance board. Providing up to 240 minutes fire protection to any project, Supalux also provides moisture resistance in damp and humid environments. Supalux is commonly used for internal partitions, external walls, internal walls, ceilings and non-combustible linings.
CEMBRIT FR
Cembrit FR is a versatile, Class A1 fire rated internal lining board suitable for partition walls, ceilings and floors. Cembrit FR will provide up to 120 minutes of fire resistance when used on the structure with insulation or 60 minutes when used without insulation. Cembrit FR building boards are lightweight and robust, making them ideal for offsite construction.
Y-WALL
Y-wall made by RCM, it is a non-combustible cement/calcium building board that can be used for applications that require a slightly lighter board with improved fire properties. Y-wall offers very similar properties to that of cement particle board, however due to the calcium additives, it offers a much greater fire resistance. This fire protection board has a smooth surface on the front and rough face on the back.
GLASROC F
Glasroc F FireCase fire protection board is made by British Gypsum and it is a highly versatile, non-combustible, Class A1 and Class 0 glass-reinforced gypsum based plasterboard used mostly as part of the FIRECASE frameless structural steel encasement system, giving up to 120 minutes fire protection and in the GypLyner ENCASE system, achieving up to 180 minutes fire protection.
MONOLUX-500/800
Promat MONOLUX (MST-500) is a robust low thermal conductivity rigid fire protection board specifically formulated without asbestos and mineral fibres for use in constructions and insulation linings. Monolux 500/800 High Performance Board is a tough and durable, resistant to impact damage fire panel providing up to 240 minutes fire resistance. While its 500 version can withstand temperature up to 900°C, Monolux 800 is classified and able to hold temperature up to 1000°C.
KNAUF FIRE PANEL
Knauf Fire Panel is a high-quality gypsum based plasterboard with additives for fire performance that is suitable for Fire-Rated partitions and any other drylining application where fire rating is crucial.
ENVIROBOARDS
Enviroboards Fire Board is a high quality cheaper alternative to Promat Supalux, Masterboard, Glasroc F and many other fire resistant boards. ENVIROBOARDS Fireboard is a strong and versatile magnesium oxide fire resistant board suitable for use both internally and externally.
TIP
Fire-retardant materials should not be confused with fire-resistant materials. Fire-retardant materials are designed to burn much more slowly.
FIRE RESISTANCE REI MARKING | 15 | 20 | 30 | 40 | 60 | 90 | 120 | 180 | 240 | 360 | MIN
Fire protection classifications are normally reported in terms of a period of fire resistance. For example, a fire protected load-bearing steel structure that can withstand fire for at least 90 minutes. The resistance to fire is the ability of a structure or an individual compartment (external wall, beams, doors, and fire barriers, etc..) to resist a determined amount of time to its stability, integrity and isolation capability. Expression in minutes (15, 20, 30, 40, 60, 90, 120, 180, 240, and 360) about the nominal fire curve. Simply, this means how elements either in combination or individually stop a fire spreading, how they restrict temperature rise and how the element's load-bearing capacity is maintained.
A range of solutions have been tested for use in a variety of fire-resistant applications, providing fire resistance periods ranging from 30 to 240 minutes to assist the design of safe buildings. For the classification of the elements not meeting the criteria R, it is automatically sufficient as long as E and I are met. The REI marking identifies the fire-resistance rating of a structure and consists of the following elements:
R - Load-bearing. The ability of a construction element to preserve its mechanical characteristics and the relevant load capacity during a normal fire.
E - Integrity. In other words, the structures ability to NOT allow the passage or production of gas or vapor to the area NOT exposed to the fire.
I - Thermal Insulation. To clarify, the ability of a structure to reduce within a temperature limits the transfer of heat to the unexposed (cold) side. The temperature limit is usually 140°C.
FIRE RATING CLASSIFICATION
Before you choose your product, it’s important to understand the classification process and what each level means in terms of fire resistance and protection. The BS EN 13501-1 classification comprises three ratings.
EUROCLASS RATING
The first is the main Euroclass rating, which will be the letter A1, A2, B, C, D, E or F. A1 is the highest level of performance, while F is the lowest. Flooring materials are followed by the abbreviation ‘fl’ (for example, A1fl). Linear pipe thermal insulation products are followed by the abbreviation ‘L’ (for example, A1L). A1 products are classified as non-combustible. A2 products are classified as limited combustibility, and B to F are classified as combustible in ascending order.
SMOKE EMISSION
The second classification relates to smoke emission during combustion. This is indicated by a rating of s1, s2 or s3, from highest to lowest performance. Smoke emission classifications are not provided for products with an E or F overall rating.
FLAMING DROPLETS
The third classification relates to the level of production of flaming droplets/particles during combustion. This is indicated by a rating of d0, d1 or d2, from highest to lowest performance. E-rated products receive a d2 flaming droplet classification.
F-rated products receive none.
A1-rated products are not given smoke emission or flaming droplet ratings, on the assumption that they make no contribution to fire growth or spread.
Occasionally, a building insulation product may focus on a Class 0 or Class 1 rating. However, these classifications do not indicate the combustibility of the product, referring only to limited surface fire performance characteristics. Class 0 is a rating defined in Approved Document B of the Building Regulations 1991. It combines two tests in the British Standard BS 476. The first assesses a surface’s contribution to fire propagation (BS 476-6) and the second assesses the spread of flames across a surface, including distance and time (BS 476-7). Class 1 is a limited classification based on the test in BS 476-7 only. It is important to recognise the limited application of these classifications.
EUROCLASS SYSTEM VS CLASS 0
The Euroclass system defining the fire performance of building products came into existence in the year 2000. It was introduced by the European Union (EU) to remove trade barriers between individual member states. Before the introduction, manufacturers had to test building products in individual countries. All of them had their own unique testing methods to define the fire performance of a product. For instance, a company from Germany which wanted to sell facade cladding panels in the UK and France, had to get their products tested in both countries in order to obtain approval to enter these markets.
The EU solved this situation by introducing a classification system that applied to all member states. However, this created new problems in streamlining existing national regulations with this Euroclass system. In the UK Building Regulations on fire safety (1991), a classification was introduced for materials used in wall and ceiling linings to determine the surface spread of flames, with Class 4 being the worst and Class 1 being the best (the least distanced and slowest spreading of flames). Class 0 indicates a Class 1 spread of flames and also takes into account the (limited) amount of heat released from the surface of a product. When the Euroclass system was introduced, countries such as the UK faced a transition period where both the existing national standards were referred to alongside the mandatory harmonised European classification. In UK building regulations, although only meant to be a transition period, both systems were used alongside each other, a situation that exists still to this day. This causes serious problems, because Class 0 simply does not indicate the same performance as the Euroclass system does.
Generally speaking, non-combustible simply means that a material does not contribute to a fire. Combustible materials have a higher calorific value than non-combustible materials and can therefore contribute to the spread of a fire. In the Euroclass system, classes B to F are combustible. The Euroclass system, which is the leading standard in Europe for fire safety classification of building materials, consists of the levels A1, A2, B, C, D, E and F. Levels from B to F are for combustible materials, although there is quite a wide variety between them. The gradation of non-combustibility is determined by the Euroclass system, where classes A1 and A2 are non-combustible and B-F combustible. A1 and A2 classifications can be given on the basis of a successful non-combustibility test. The calorific value is defined here, which should be of a very low value. The Euroclass system is based on a stacked level of testing: with every class, there are more strict rules to comply with. In class F, either nothing is tested or a product fails to achieve a higher level. Class E only tests with a small flame for a short time. For classes D to B, the method of SBI-testing is used. Lower classifications (Euroclass C to F) are even less fire safe. An F classification even means the material hasn’t managed to pass any of the tests for a higher class.
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