As a Chartered Quantity Surveyor, Linda Lodetti has spent most her life providing construction cost advice in South Africa, the United Kingdom and New Zealand. She is also the author of New Zealand’s first Costing Timber Guide, which looks at the benefits of mass engineered timber and the factors impacting on cost in mass engineered timber projects.
Innovations around the world have resulted in new manufacturing and processing techniques delivering a range of engineered timber products, including Laminated Veneer Lumber (LVL), glulam, Cross Laminated Timber (CLT) and cassette flooring systems, to name a few.
The strength and performance of these products can depend on tree species, thickness, manufacturing process and application, and means construction costs may not be certain. This can potentially lead Quantity Surveyors to provide overly cautious budgets for new mass timber solutions – something that has been recently criticised in the industry.
“For Quantity Surveyors, assessing project risk in the absence of historical cost data or benchmark projects can lead to contingency factors being included in the project budget,” says Linda. “These allowances can often bump the price up substantially, and may even have the potential to kill the viability of a project. The Costing Timber Guide attempts to avoid this happening by exploring the factors impacting on cost and building greater understanding of the value of engineered timber.”
During the preparation of the guide, Linda says it became evident that timber manufacturers also needed to understand Quantity Surveyors’ estimating and pricing processes.
“I developed a two-fold agenda explaining how Quantity Surveyors approach costs per m2 of GFA (requiring historical data), elemental analysis of the proposed construction project, and trade costs based on developed detailed drawings. With a more transparent view of how QSs come up with their costs, timber manufacturers can better understand the areas where further information is required to assist with compiling appropriate budgets.”
The guide explores key aspects of mass timber, including ‘When is mass timber appropriate to use?’ and ‘The value propositions of timber solutions’. Linda says one of her favourite examples is where underlying soil conditions are poor.
“At 1/5th the weight of concrete and less dense than steel, mass timber presents a solution for projects where the soil isn’t ideal for traditional solutions. For example, construction work at a popular Christchurch backpackers was initially not financially feasible using traditional piling and steel, but timber piling and CLT panel structures presented a viable option. A retirement village in Christchurch was another project where preloaded gravel and concrete floor slabs with CLT panel structures avoided the expense and risk of traditional piling foundations.”
As more projects are completed using mass timber, more cost information for different project types will become available – arming QSs with the historical data they need to form accurate budgets.
Collaboration is key
Linda worked with Martin Bisset of QV Cost Builder to include extracts from the paid on-line service, which provides trusted analysis and cost data.
“With extracts from QV Cost Builder, we were able to show what level of information cost plans are based on at the Concept Design stage, as well as what cost data looks like when the measures move to Elemental Analysis as the design develops, then finally at the Detailed Design stage. It’s ultimately collaboration with all parties involved that led to a successful outcome.”
Why support mass timber solutions?
Linda is clear that the guide does not suggest steel and concrete don’t have a place in design solutions. Instead, it highlights when mass timber is appropriate to bring to the design table.
“The value of timber goes beyond bottom line costs. Experienced QSs will know that you need to look at the big picture, and this can only happen through collaboration around buildability issues with all those involved – from the design engineers and suppliers to the proposed (ECI) contractors. When considering mass timber solutions, quantity surveyors need to be challenged to assess what this innovative product can bring to the table, what the cost drivers are, and where other costs may be reduced as a result.”
Right now, Linda says direct comparisons of traditional steel frames with structural timber show mass timber as the more expensive option. Unravelling that means looking at the full picture:
- Can timber result in reduced foundation loads and costs?
- Can costs be reduced due to shorter programme durations?
- Can scaffolding costs be reduced due to site methodologies?
- Can waste removal be reduced on site?
- How much is early occupation worth to the client in potential earlier income?
What about our carbon footprint?
Timber is the only truly renewable construction product, and using timber from sustainably managed certified forests offers a real solution to reducing our carbon footprint.
“Timber’s stored and sequestrated CO2 properties are far greater than that of steel – the production of which is destroying our air quality,” Linda explains. “Timber is also not as demanding on our water resources as concrete production. All of this adds to the merits and value proposition of mass timber.”
In July 2020, the Ministry of Business, Innovation and Employment (MBIE) launched Building for Climate Change: Transforming the Building and Construction Sector to reduce emissions and improve climate resilience. This programme aims to help the Government achieve its Carbon Zero goals by 2050, and will require changes to the Building Code and consent requirements – targeted for implementation in October 2021. “A key part of reducing our carbon footprint must be careful consideration of the construction products and methodologies we use. It’s time to have that difficult conversation about how the construction industry can contribute to the future of our planet – and I believe it will see mass timber become the preferred building product.”
Linda is also the author of the ‘Costing Timber Guide’ – sponsored by the Wood Processing Manufacturing Association and one of the many technical guides published by NZ Wood Design.