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Informative

Cost Engineering: Mass Timber vs. Concrete & Steel

12 minutes
November 17th, 2022

Cost engineering is a standard exercise of determining a project’s cost. It includes comparing the price of materials, among other factors, to establish the likelihood of a material being specified for use.

This is where mass timber construction comes in – being an alternative to replace conventional materials like concrete and steel. Thanks to technological advances and continuous improvement in manufacturing, mass timber solutions can be the most cost effective option.

As with any construction project, pre-planning and cost estimating is one of the deciding factors when it comes to material selection. WoodSolutions, an independent body that provides non-proprietary information about timber and wood products, developed a Cost Engineering Guide for Mid-rise Timber Buildings to help with cost estimating for engineered wood products (EWP).

The Wood Solutions Mid-rise Timber Buildings guide is based on the observations recorded from 26 significant projects and identifies the differences between costing of wood-based projects with respect to those using other systems. Read the full guide here.

Throughout the blog, you’ll learn why timber should be the most cost-effective option in different mass-timber building scenarios and how you can apply it in real cost engineering situations.

Cost Savings

Cost saving is one of the most important aspects of any build and can be broken down into a number of areas, from actual price to reduced labour to time and operational-related savings.

The Wood Solutions table below outlines the general cost savings of timber vs conventional materials, demonstrating a 7-storey office structure made of timber solutions, such as MASSLAM (ASH’s range of mass timber columns, beams, floor and roof structures), offer the largest cost effective options with a saving of $1,141,485.

Derived from the Wood Solutions guide, we have listed ways in which timber-based options can save time and budget, using MASSLAM as an example.

Differential value

Due to the high strength to weight ratio of mass timber, and in particular, MASSLAM, cost effective elements are possible when optimising designs. With smaller sections due to better strength, MASSLAM can increase the net sellable and rentable areas by facilitating more usable space. Highly attractive structures also boast a higher rental yield.

ASH’s processes also mean fewer variations and defects in the product and our Hundegger CNC typically machines to within +/- 1mm accuracy to the parameters in the 3D model. This results in better accuracy and reliability than alternatives.

Being the structure and the aesthetic, mass timber is a more responsible use of material which helps toward a more cost efficient solution to achieving some green building targets/schemes.

450×450 MASSLAM columns in the University of Tasmania Burnie Campus.

Improved Safety

Site safety is an ever-increasing priority when determining cost. Using timber instead of alternatives means you typically use larger working platforms, pre-installed edge protection and simpler anchoring for safety harnesses.

Due to the prefabricated nature of mass timber, the material is easier to handle and fix with lighter tools, and no hot works or welding on site. The outcome means 90% less waste during the structure stage and reduced waste in the finishes.

Faster Delivery

Faster delivery equates to less down time costs. Follow on trades can start much sooner because the floors are readily stable and load-bearing, and a higher number of members per truck leads to accelerated install programs.

Manufacturers typically provide BIM-ready shop drawings to ease of instalment. Below is an example of a MASSLAM loading plan that demonstrates the precision planning from a mass timber manufacturer during production.

Lower Preliminaries

Overall preliminary costs can be reduced from timber and create a positive flow on effect. Wood products are a lighter material than conventional options like concrete, which means lifting is quicker and can be achieved with smaller cranes and/or shorter equipment rental times. The result is shorter on-site programs with limited scaffolding, smaller and more organised storage areas and less site accommodation due to smaller crews.

Reduced Labour

Another benefit from engineered wood products are the lessened costs from reduced labour through time savings. The less time it takes to build, the shorter the labour timeframe.

Outlined in the Wood Solutions guide, approximate time savings were found for various follow-on trades based on 26 projects:
• services (MEP) – about 30-50% faster
• dry liners – about 20-30% faster
• window & door installers – about 20-30% faster
• insulation installers – about 20-30% faster
• cladding installers – about 20-30% faster

Reduced Foundations

MASSLAM columns and beams have some of the best weight-to-strength ratios, which creates a lighter above-ground structure with respect to reinforced concrete. This reduces the foundation size and significantly improves designs in solid and vertical extensions over existing buildings. Some projects even experienced higher build volumes.

This is where engaging with mass timber suppliers during the design stage is imperative and can result in major cost savings across a multitude of areas.

560×65 and 560×85 MASSLAM beams in the Hope Anglican Church.

Lower Impacts

In addition to direct cost savings, projects using engineered wood products experience less noise, dust, vibrations and truck movements.

Other intangible advantages include gaining credits for CO2 storage as the timber members are a carbon sink and renewable materials are often applicable for additional accreditation like Green Star. Exposed timber elements also have demonstrated benefits to occupants’ health and wellness as detailed here, which may justify higher rental fees for commercial and multi-residential builds.

EWPs are also typically cut to a tolerance of 1mm and sealed with tape during their assembly, meaning that, where used as external walls, they can deliver an airtight envelope to the building (subject to good window and door fittings).

Price changes

Over the past few years, the impact COVID shifted the demand for building materials exponentially, with shortages experienced worldwide due to an increased number of projects and more need for local products both in Australia and internationally.

These changes led to shipping volatility and a price increase of 30% for steel & aluminium, 50% increase in imported timber and only a ~5% increase in MASSLAM YoY. Supply risk is also overcome when using MASSLAM because ASH produce our own timber. We produce from log to finished product. If we have your project committed to production, timber supply is guaranteed.

 

All construction materials require unique consideration of their advantages and limitations to maximise cost efficiency. MASSLAM can be the most cost effective of all systems but this may not be the case if you design for concrete or imported mass timber and hope to compare price. This is why it is imperative to talk with a MASSLAM specialist early in the design stage to ensure the best cost outcome.

Learn more about mass timber by watching this DfMA GLT Members Seminar.

View MASSLAM projects here