Fire safety is a hot topic
Design and material specification can play an essential role
Design and material specification can play an essential role in curtailing the spread of fire and smoke in buildings. By Yamurai Zendera
Thomas Bohlen, chief technical officer for the Middle East Centre for Sustainable Development (MECSD), argues that the rapid spread of flames at Al Barka and Al Tayer towers this January and May, respectively, was unfortunately aided by the type of cladding used on the facades.
A professional architect, Bohlen says both incidents have focused minds in the UAE on ensuring that tower-block exteriors are constructed with greater fire-resistant materials to prevent buildings from burning so fast that occupants are not able to escape safely.
“One of the issues that have cropped up in the UAE in the last couple of years is the metal panels on the outside of buildings. The metal cladding panels are insulated.
The low fire-resistive styrene installation is what is burning fast, so when these façades catch fire, for whatever reason, the flames quickly and completely engulf the entire façade like a roman candle.
It does not give time for people to get out of the building because it’s spreading rapidly. Fortunately no one was killed in either one of these tower fires but they displaced hundreds of families. A lot of people lost everything in those burned out apartments,” he says.
“Soon after these fire events, the Dubai Municipality and other emirates issued some tougher rules on specifying and approving the use of fire-resistant panels on building exteriors, which hitherto had not been recognised as a problem.
There are several types of panels available on the market with differing fire resistance and ratings, and from now on the façades on the new buildings will have a greater fire resistance.”
But Bohlen, whose job at MECSD involves working with clients through LEED certification process, says there is still the “looming problem” of who is going to retrofit the large number of existing commercial buildings in the UAE that may have low fire-resistive cladding.
And, as he makes clear, there is no point talking about green sustainability if buildings are susceptible to burning down in an instant.
“There is an estimation of about 500 buildings across the UAE that still have these low fire-resistant panels on the façades, and so that is a looming problem out there – that, if these buildings do catch fire, they are going to burn very fast. So that is something that is not easily fixed or remedied at this point without great effort, a lot of time and much cost.”
Jean-Philippe Kayl, a fire-testing manager at consultant Thomas Bell-Wright, which claims to have the only fire testing laboratory in the region, sees manufacturers come to validate new product designs that will be used in their buildings.
“There are two main areas of fire testing: resistance to fire testing and reaction to fire testing. The aim of fire resistance is to measure in minutes or hours the time duration of a full-size assembly (such as door, wall, partition, curtain wall, ceiling, penetration seals, dampers, etc.) while physically engaged in a theoretically-reproduced fire scenario in accordance with international standards. Based on the test results, the assembly receives a fire rating,” he explains.
“Unlike resistance to fire, which is suitable for full-size assemblies, reaction to fire testing is rather dedicated to single materials. The test measures the combustibility properties of the material to understand how it will contribute to the growth of the fire within a building.
In addition to the testing of products and systems, product certification is a necessary part of the process to ensure that everyday production meets the continued performance of the tested sample.”
Jason Hird is a technical development manager for Saint-Gobain Gyproc Middle East, which provides passive protection for the spread of fire through a whole range of fire-resistant plasterboard systems.
The three main areas it is concerned with are: walls/partitions, wall linings and ceiling systems. The firm either fully fire tests every system it makes, or it has them assessed by an approved and accredited third-party company, it states.
Hird says that, in the UAE, the traditional method of building wall partitions is with blockwork. However, he points out that awareness needs to be raised about the many extra benefits of using fire-resistant plasterboard systems.
“Blockwork is very time-consuming, slow and messy to install, and it puts a lot of extra weight into the building. We design and manufacture plasterboard systems to meet particular performance criteria that easily provide up to three hours’ fire resistance.
“As well as partitions, we also look at ceiling systems, again for fire resistance, because sometimes there is a need to protect the area or the space, sometimes called the plenum, above the ceiling lining.
Gyproc ceiling systems can provide you up to two hours’ fire resistance to the plenum. We also do wall lining systems. If you have got blockwork, we can also provide you with systems that line those walls to increase acoustics, fire resistance or the aesthetic appearance of the system.
Hird says that, when it comes to fire-safe construction, one of the most common building solutions for passive fire protection is ensuring that compartmentalisation is specified correctly and is in line with local government requirements.
These ‘separating elements’, such as partitions and walls, are typically graded by their fire resistance, which is normally made up though integrity and insulation, and for some constructions load-bearing capacity may also be a requirement.
Fire resistance is stopping the passage of flame and heat and, in addition, smoke from one area to another. Failure is flaming coming through a hole, gap or fissure caused by the fire, which flames for ten seconds.
Integrity is how long the separating elements stay in place and stop the passage of flame. Insulation is about keeping the temperature of the unexposed face of the separating element from getting too hot; typically, the failure is 180°C above the starting temperature.
The best way of protecting structural steel in a fire situation of is to box out the steel in plasterboard. Steel typically loses its strength, or load-bearing capacity, at around 550°C. Gyproc plasterboards, including the Glasroc range, provide up to three hours’ fire protection.”
Afschin Soleimani, director: fire and risk engineering at consultant Ramboll Middle East, says fire engineers are often faced with questions on how a certain required fire rating can be achieved. A fire separation could be structural or a fire compartment wall or floor.
“In case the fire separation is required to function as a compartment wall or compartment floor, the fire separation in question will be required to maintain its integrity during a standard fire-rating test.
In addition, any such fire separation will be required to provide sufficient insulation on the fire side, in order to avoid an excessive increase in temperature on the non-exposed surface. If the fire separation serves as a structural wall or floor, it would also be required to provide a load-bearing capacity to resist collapse as a result of a fire.
“In order to meet the above design criteria, it is not enough just to utilise non-combustible materials or to increase the thickness of a wall or floor. In fact, a combustible wall or floor such as a wood floor or wall could also meet all three design criteria.
In order to qualify, the entire wall or floor assembly has to be tested as an assembly in order to determine if such assembly meets the design criteria for the duration required by the applicable building or fire codes. Any wall or floor assembly to be utilised as a required fire-rated fire separation should be listed and published by a recognised testing laboratory.
“In case of a drywall assembly, every detail of the proposed wall has to be in line with the specifications of the listed assembly. These specifications include the type and thickness of the gypsum wallboard, type of material used for closing wallboard joints, details of screws and details of the steel studs and any other specifications listed.”