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Selecting Appropriate Fire-Retardant ACP/MCM for Façade Cladding

By: Nikhil Joshi, Emerge Metal Industry LLC

Façade, better known as fascia, means “FACE” in reference to the front part or exterior portion of the building. The façade of a building is often the most important aspect from a design point of view, as it sets the scheme for the rest of the building. Façade is also of great importance due to its impact on visual appeal and energy efficiency.

The outside walls of contemporary high-rise buildings are frequently suspended from the concrete floor slabs. Precast concrete walls and curtain walls are two examples. When two buildings are very close to one another, for example, the façade may occasionally be required to have a fire rating to reduce the risk of fire spreading from one building to another. Many materials are recently used in covering the façades to give aesthetic looks and functionality also. Cladding is a material used in construction to give structures a certain amount of thermal insulation, weather protection, and aesthetic appeal. There are a variety of materials that can be used to make cladding, including wood, metal, brick, vinyl, and composite materials comprised of aluminium, wood, recycled polystyrene, and wheat/rice straw fibres. A type of weather cladding called rainscreen cladding provides both thermal insulation and protection from the elements.

As a control element, the cladding does not necessarily need to be waterproof; it simply needs to be able to properly divert water or wind away from the building structure to manage runoff and avoid water intrusion. Cladding might also act as a noise control measure, either for entering or escaping noise. By design or construction, cladding can provide a fire hazard but can be prevented with the right selection of material. Commonly used material for cladding is metal and its composite material comprises aluminium, zinc, copper, stainless steel, etc. depending upon the requirement of the project. The most easily available composite material is aluminium composite material.

Aluminium composite material (ACM)

Generally called aluminium composite panels (ACP), are flat panels consisting of two thin coil-coated Aluminium Sheets bonded to a non-aluminium core. Core composition keeps on changing as per the final usage of the product. ACP is mainly used for external and internal architectural cladding. However recently with new technology developments, it is also used for partitions, false ceilings, machine coverings, container construction, etc. ACP is also widely used within the signage industry as an alternative to heavier, more expensive substrates.

ACP has been utilised in a building as a thin but incredibly strong material. Innovative design with greater rigidity and durability is possible thanks to its flexibility, low weight, ease of forming, and processing. Polyvinylidene fluoride (PVDF), fluoropolymer resins (FEVE), or polyester paint can all be used to coat aluminium sheets. Any colour may be painted on aluminium, and a vast variety of metallic and non-metallic hues, as well as designs that resemble other materials, such as wood or marble, are made for ACPs. low-density polyethylene (PE) or a combination of PE and mineral material or non-combustible material with fire retardant qualities is frequently used as the core material. For better understanding let’s divide the product into more segments and study each segment step by step.

BASIC CONFIGURATION OF PRODUCT

• Protective film is to protect the paint applied to the aluminium coil.

• Paint is PVdf/Feve in case of exterior application use and HDPE/PE in case of interior uses.

• Coil of aluminium can be of 1XXX, 3XXX and 5XXX Series Alloy

• Adhesive film used to laminate top coil to core should be of reputed brand

• Core can be low-density polyethylene in case of signages or non-combustible mineral filled in case of exterior application

• Adhesive film used to laminate the bottom coil should be of a reputed brand

• Bottom coil is either mill finish or with service coat in some cases depending upon end usage

There is a warranty for products given by the manufacturer which generally ranges from 10 – 30 years depending upon the raw material used.

TERMINOLOGY

Understanding the distinction between “Fire Resistance” and “Reaction-to-Fire” is crucial. Even, though paper used in daily items has a fire rating, but it’s very low. Will you accept this? The answer is no. The term “Reaction-to-Fire” applies better to the materials. It addresses flammability, ignition, the spread of the flame, the production of smoke, burning droplets, and toxicity. Since we are talking about ACP/MCM, which is a façade material, “Reaction-to-Fire” rather than “Fire Resistance” is the proper phrase to use when choosing ACP/MCM. Fire resistance relates to a building’s ability to compartmentalise systems like walls, doors, ceilings, etc.

Operating terminology “Fire Resistant” is not pertinent to ACP/ACM, “Fire Retardant” is the correct terminology. Hence, Fire Rated/ Fire Resistant/ 2-hour Fire Rating terminology is not relevant for ACP/MCM. The appropriate terminology is “Fire Retardant ACP/ MCM”. As previously stated, the “Reaction-toFire” of façade materials is crucial to both carrying out rescue operations and containing the spread of fire. Smoke and toxicity, not necessarily fire alone, are the main causes of human loss in structure fire accidents.

Combustibility, Ignitability, flame spread, and burning droplets are crucial factors to take into account while addressing the spread of fire. However, smoke development and toxicity are the most important factors for occupant safety as well as for fire brigade rescue operations.

SELECTING THE APPROPRIATE FIRE RETARDANT ACP FOR USE IN THE FAÇADE FOR CLADDING

Building fire safety starts with the planning phase. It has become more difficult and complex to reduce fire danger, especially in areas with a lot of people traffic, like large athletic venues, public transit hubs, hospitals, schools, and high-rise structures. A crucial aspect of façade design is the Fire Engine’s height restriction so that it can access the upper floors.

Recently, several high-rise structures in India have mandated the use of fire-resistant materials for building façades. However, there is still a great deal of uncertainty when selecting suitable materials because of the consideration of inappropriate or insufficient information while purchasing these components. Regardless of the rules, it is crucial for users to pick building materials of the proper quality to minimise harm to both people and buildings.

To reduce the risk of a fire, it is important to employ the appropriate products, systems, and environment. Suitable fire retardant FR material must also be used. If fire result retardancy is prescribed at the correct performance level, “real” FR material must be shown by passing a difficult system test with a multi-story setup.

WHAT CONSTITUTES A FIRE RETARDANT CLADDING SOLUTION’S PERFORMANCE?

• The extent of smoke and droplet emissions.
• The amount of lateral and vertical fire propagation.
• The amount of self-extinction of the fire on the panel.
• Applicable to all system components such as insulations, framework, fire barrier, smoke seals etc. used for installation

When it comes to ACP cladding, it is advisable to use systems without sealants or, if necessary, sealants that are fire retardants.

TEST METHOD FOLLOWED

Commonly followed standards and test methods are the American Standard of Testing Methods (ASTM), British Standards (BS), European Nations Standards (EN), and Deutsches Institu Fur Normung e.V. (DIN).

Therefore, NFPA 285 or BS 8414-1 in addition to EN 13501-1 and ASTM E-108 must be passed by the ACP/MCM for optimum Fire-Retardant ACP/MCM. It can be concluded that ACP/MCM is a very versatile, lightweight and long-lasting material with good benefits if the right selection of ACP/MCM make is done. It is recommended to use a product that is certified by various testing agencies, government bodies and proper in-house laboratories for a consistent product. Hope this article would be useful to you in the long run and for any further information about ACM or cladding you can get in touch with me by email.