Cross Laminated Timber Trend | Progressive Materials WA

What is mass timber?

Mass timber or ‘massive timber’ is a generic term used to describe any building or structural system that uses wood, other than ‘light’ wood or ‘stick-framing’. It is composed of layers of wood joined together to form strong panels or beams. There are different types of mass timber such as the glue-laminated (glulam) beams and laminated veneer lumber (LVL) but the most common and most familiar product used in the construction industry is cross-laminated timber (CLT). With the industry shifting away from concrete-based construction, cross-laminated timber (CLT) panel products are considered as economic and more sustainable alternatives to traditional materials.

Advantages of Cross-laminated Timber

Similar to plywood, CLT is an engineered wood product that is comprised of layers of timber glued together with the grain running in opposite 90⁰ angles. It has been praised in the construction industry for its sustainability, efficiency, strength and durability.

3 main benefits of using CLT in combination with steel and other building materials:

Strength
Despite being five times lighter than concrete, CLT’s perpendicular layers make it stable and strong in two directions. CLT panels have comparable strength per weight ratio to concrete which has enabled an increase in high-rise all-timber constructions.
Additionally, they offer excellent thermal, seismic, fire, and acoustic performance, adding exceptional protection and dependability.

Versatility
CLT can be used in several applications, from walls to floors and roofing. It can be used in conjunction with other building materials such as steel and concrete to offer additional support and allow for creative and flexible architectural designs.

Sustainability
CLT has a low environmental impact since it is made out of renewable wood. Compare to other commonly used building materials, it sequesters carbon and does not require the burning of fossil fuels during production, it also produces very little onsite waste and any waste that is produced can be reused or recycled for other purposes.

Engineered timber is commonly used in combination with steel and concrete materials in many of the high-res buildings all over Western Australia on a commercial scale, as well as for residential projects. Most mass timber projects have hybrid structural systems, which contribute to their cost-effectiveness. Projects often combine mass timber floors and ceilings with light-wood-frame walls or steel seismic frames for greater economy or introduce steel-and-concrete core elements where they make sense for cost and structural efficiency.

Passive Fire Protection (PFP) Systems for CLT Buildings

While not always recognised as a viable structural material, structural timber has inherent fire-resistant properties and when used in compliance with the NCC requirements, it becomes a good material for both mid and high-rise buildings.

Australia’s National Construction Code (NCC) guidelines define performance requirements for buildings exposed to fire. All building work (new construction, additions and alterations or change of use of a building) must comply with these requirements to facilitate the safe evacuation of building occupants and minimise the damage to other properties. There are specific requirements that Australian architects and specifiers must bear in mind when designing timber-structured buildings:

Fire penetrations and C3.15 – All service openings in walls and ceilings must be sealed to prevent the fire from spreading through the building. Each CLT manufacturer requires a suite of testing that is specific to their CLT product. Fire stopping materials to seal service penetrations of the building such as fire pillows, fire batts, fire mortar, fire mastic, fire collars and other fire sealant products are essential to a complete passive fire protection plan in timber structured buildings.
Fire protection system for CLT floor plates and structural elements. Floor plates are required to be tested to AS 1530: Part 4, and depending on the required FRL might incorporate fire rated plasterboard to achieve higher FRL’s. CLT structural elements often have steel connection plates- these also need to be tested to AS 1530: Part 4 and AS4100 in relation to the protection of steel structures – Structural steel frames (columns and beams) used in combination with cross-laminated floors must be protected from fire to preserve the structural adequacy of the steel structure.This can be achieved using intumescent paint, spray coatings (vermiculite spray) or fire rated boards systems.