By Paolo Lavisci, WoodSolutions
While many risks are common across all building materials and systems, it’s important to understand how Engineered Wood Products (EWPs) may be different and what you should be aware of when assessing a timber project.
One of the perceived risks for timber mid-rise construction is fire safety. However, timber construction achieves the required performance under the National Construction Code’s Deemed-to-Satisfy (DTS) solutions for fire-protected timber construction up to an effective height of 25 metres.
EWPs in fact, have a very predictable and well-documented fire behaviour and maintain their strength and stiffness when temperatures rise. Understanding and designing for these factors is critical to demonstrating that a performance-based fire strategy will meet building code requirements and has successfully been done in several cases.
Construction safety, speed and quality
Using EWPs has been demonstrated to enhance site safety. Significantly high levels of construction safety are the major driver for both efficiency of installation, and absence of defects. But quality cannot be controlled, if it hasn’t been designed, therefore it is important that design resolution and clash detection are completed before shop drawings and production. This is an easy task with EWPs because of their accurate dimensional tolerances, while minor on-site adjustments are very simple to carry out, if required.
While structural elements are fabricated off-site, on-site activities centre around the assembly of the structure and the rate at which they can occur. Analysis of the 26 projects within the WoodSolutions database shows the following “average project” data: the wood carpentry for a 7-storey building, with a gross internal area of approximately 8,000m2, is installed by a crew of 7 at a rate of 92 m2 per day. Of course, installation rates can vary and are very project-specific, but in general terms they are significantly faster than with other materials.
Quality Assurance is a simple task with EWPs, because highly automated processes are normally used, in which all the materials are tested, recorded and tracked throughout the production line. As with any other products, it is important that all elements installed are compliant with the specified design.
As for the financial risks, when the level of off-site manufacturing increases, suppliers may require a substantial deposit well in advance of delivery. But for EWPs this may be balanced by the time savings that, in most cases, mitigates this risk.
EWPs have historically shown less price volatility than other materials and, although this is a hot topic at the time of writing, there are already signs of a decrease in the future price indexes. Most analysts expect that the associated supply crunch will soon start to progressively ease, while the industry is already investing to improve its capacity.
As wood-based projects require design to be largely resolved before the elements can be produced, projects often experience fewer variations than is common with other materials that have larger tolerances and require more site work.
In general terms, significant advantages can be found in a fast and predictable building process, where the accuracy of EWPs plays a major role.
The WoodSolutions Fact Sheet #17 on Mid-Rise Insurance is a useful reference you can download.
For more information, expert advice, case studies and technical design guides head to the WoodSolutions website https://www.woodsolutions.com.au
Images 1 and 2 - La Trobe Student Accommodation
Multiplex completed the 624-bedroom LaTrobe Uni Student Accommodation in Bundoora. Architect: Jackson Clement Burrows
Photographer: Glenn Hester
Image 3 AVEO Bella Vista
The AVEO Bella Vista building, completed in Norwest, Sydney in 2018, breaks the mould of the typical mass timber designs for residential buildings we have seen internationally over the past decade.
Architect: Jackson Teece
Photographer: Brett Boardman