Timber charring can achieve the same level of fire resistance as other building materials
Mass Engineered Timber (MET) is a building material growing in popularity in Singapore, and comprises engineered wood products with multiple benefits. MET is environmentally sustainable, lightweight and durable, and is highly fire-resistant. As a form of DfMA (Design for Manufacturing and Assembly) technology, MET allows for modular construction through offsite construction, facilitating custom designs and greater on-site productivity through faster assembly.
Mass Engineered Timber is primarily manufactured from sustainable softwood species in Europe. It comprises both CLT (Cross Laminated Timber) and Glulam (Glue Laminated Timber), for use in the construction of various types of developments, such as commercial, infrastructure and institutional buildings.
Mass Engineered Timber has garnered rapid acceptance, both in Singapore and across the globe for constructing both low and medium-rise buildings. It is loved for its high structural integrity as well as a classy aesthetic. As an engineered product, it can also be crafted to specific design requirements, ensuring better quality control through precise and automated manufacturing processes. It is also prefabricated offsite, achieving significant time savings as well as reduced dust and noise when commencing onsite construction.
In addition, Mass Engineered Timber offers respectable fire resistance, making it ideal for commercial construction in Singapore, which is why it forms a key component of SHEVS IFT’s fire safety engineering designs.
MET is a category of timber product which comprise of multiple wood panels glued together to provide exceptional strength and stability.
As an alternative to concrete and steel, there are 2 common types of MET:
Cross Laminated Timber (CLT)
CLT comprises of at least 3 to 7 glued layers of laminated timber stacked perpendicularly to each other. These layers are bonded with structural adhesives.
CLT is commonly used for prefabricated wall, floor and roof panels.
Glued Laminated Timber (GLULAM)
GLULAM comprises of many small sections of plane timber boards bonded together with structural adhesives. These layers are aligned with the timber grain in the same direction.
Due to its strong mechanical properties, GLULAM is commonly used for structural beams and columns.
Early Involvement of Contractors and MET Specialists
Early engagement of the MET specialists and the main contractor during the design stage of the project is very important to ensure a smooth delivery of any MET project.
The Stakeholders for any MET project consist of:
MET Specialist’s Inputs
With MET specialist’s inputs during the early design stage, a more effective technical MET solution can be achieved in terms of prefabrication, delivery, coordination and installation.
It is also critical for the consultants and builders to consult the relevant regulatory authorities early prior to the final fabrication of the MET products.
Compliance With Fire Safety Requirements For MET Buildings
Like concrete and steel buildings, MET buildings must comply with the fire safety requirements in the prevailing fire codes.
Conventional structural elements like concrete and steel are considered as non-combustible materials. As MET is a combustible material, additional fire safety requirements are mandatory to use MET for building construction.
For the Singapore Chapter, the additional fire safety requirements are:
Habitable height limit < 12m
The habitable height of any occupancy in an engineered timber building shall not exceed 12m, including mezzanine levels.
All MET buildings must be protected with sprinkler system.
Performance-based Approach for MET Buildings
In any case that the habitable height of the building exceeds 12m, the MET building design must be submitted to the AHJ via the performance-based approach.
Relevant design codes and guidelines:
Behaviour of MET when Exposed to Fire
When MET is exposed to fire at elevated temperatures between 200°C and 300°C, a process called pyrolysis occurs where gas emissions from combustible components burst into flames. This pyrolysis process gradually spreads across the timber surface resulting a charred layer. The charred layer then acts as an insulating layer, preventing the inner core from further heating. Unlike concrete and steel which are non-combustible, the charring nature of the combustible timber can naturally protect itself with excellent fire resistance.
Fire Resistance Rating of the MET
Fire resistance is defined as the ability of a material or their assemblies to prevent or retard the passage of excessive heat, hot gases or flames under conditions of fire.
A fire-resistance rating is defined as the period of time that a building element, component or assembly maintains the ability to confine a fire (separating function), and/or continues to perform a given structural function.
Timber charring offers fire performance.
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