Mitigating the Risk of Fire Trough Cladding
Following cases of cladding materials posing safety concerns, most manufacturers and contractors have started shifting to cladding materials. Earlier cladding materials mainly focused on improving the appearance of the building and offer insulation against environmental factors such as rain, wind and the sun, but there was little concern about safety.
Fire is a potential risk in any building, meaning the material used should be a deterrent to its spread instead of fuelling it. Cladding fire protection capability mostly depends on the material chosen. Cladding materials that do not combust easily will protect the building structure by slowing down the fire spread. Some of the fire-resistant cladding materials include Brick, Steel /cement planks and aluminum.
Understanding the Problem
The spread of fire through the external cladding materials is one of the quickest ways in which fire can spread in buildings. The three most common situations that can lead to fire spread through the external surface are:
- Fire started by an element that burns in front of the external surface
- Fire from outside, e.g. from a nearby burning building or bush fires
- Fire that starts within the building but spreads outwards through the windows
Most cladding materials have a cavity between them and the wall where wain water runs down. The cavity can also contribute to fire spread by allowing the fire to spread up through the gap. These gaps act as a chimney in case of fires by drawing hot air up. With hot air moving up, the flames burn stronger and move all the way up from the origin of the fire to the top causing more damage.
External surface fire spreads are a challenge to fighting the fire as they undermine all the methods of control and protection that fire-fighters use when dealing with such scenarios. It is easier to fight a fire confined in a single story than when the rate of spread is high. Fire burning in the exterior is also a risk to the nearby buildings, especially if the cladding is flammable.
Solving the Problem
Most of the cladding materials used in buildings can enhance the spread of fire as seen in cases such as the Grenfell Tower fire in London and the Downtown Dubai fire in 2016. Following such incidences, people have started focusing on constructing houses in a manner that will prevent fire spread using fire-resistant materials.
No material is completely fireproof, but fire will take longer to affect fire-resistant materials giving enough time for rescue operations as well as fighting with the fire. Contractors are focusing on using a material that will slow down the spread of fire to the outside as a fire safety measure. Materials have been tested on how fire affects their structural capability. The effectiveness of cladding as a method of protecting buildings from fire depends on the fire resistance capability of the material used. Below is a ranking of cladding materials from best to worst.
Brick (Excellent Fire Resistance)
Brick is one of the oldest construction materials used all over the world due to its availability and strength. The material is considered as one of the best cladding materials due to low maintenance needs, it is recyclable, and it is aesthetically pleasing. The fire resistance capability of clay bricks is also an added advantage given that it can prevent a fully developed fire for quite a long time. The material is among the most trusted cladding materials in providing fire protection.
Fibre Cement Cladding (Excellent Fire Resistance)
Cement cladding adds a further improvement to the appearance of your home and provides a weather coat to exterior spaces such as composite decking. One benefit of using the material is its long service time and zero maintenance cost. Most of the manufacturers give a 10-year warranty against rotting and warping of the material, knowing that it can serve you for more than 60 years under extreme conditions. The maintenance cost is also low as it does not require regular painting or treating.
In addition to all the above benefits of fiber cement cladding, the materials’ most significant benefit is its resistance to fire. The material is leading in fire rating, meaning that it has low combustibility and produces less smoke in fires. Tests have also shown that fiber cement does not combust from direct contact with fire, and it does not fuel an existing fire.
Aluminum Cladding Products (Good Fire Resistance)
Aluminum is well known as a decking board and is also gaining popularity in the cladding. The main reason why aluminum is preferred in an outdoor environment is its durability as it can resist most of the harsh conditions of an outdoor environment. The metal is also very light and can also be fabricated into different shapes to fit cladding requirements and even in composite decking. The performance of aluminum in fire resistance is good but not excellent because installation requires other materials.
Timber Weatherboard (Poor fire Resistance)
Timber is a common cladding material for walls and also a composite decking board material due to its attractiveness and durability. Despite its attractiveness in exterior surfaces, timber cladding is not the best choice when it comes to safety. The major disadvantage of using timber cladding is its risk of spreading fire. Timber is a flammable material and is more likely to catch fire when it comes into direct contact with fire. Most wood claddings are painted or sealed, but that can never be enough for an uncontrolled fire common in most residential areas.
Plywood Sheet Cladding (Poor Fire Resistance)
Plywood sheet cladding is mostly used as a substitute for wood cladding due to its low price with the same features. The other advantage is that the material has increased strength and is lighter than wood while still maintaining the same appearance as wood. The main disadvantage of plywood is that it is not fire-resistant. Wood is flammable and is more likely to spread the fire from one part of the house to another, making it hard for fire fighting and rescue operations.
The incidents of fire spread by the cladding materials in several fire incidents around the world have led to a change in how contractors and house owners use cladding materials. Most of the engineers and contractors are changing their focus in cladding towards fire safety even if it costs more time and money. Most governments are also making regulations and building codes to be followed by contractors in regards to the types of cladding to use for specific kinds of buildings as well as the design.