Engineered Timber - Finances + Method
An interview with Paul Gardiner detailing the firms experiences working with mass timber construction methods
How does engineered timber stack up financially compared to traditional construction methods like concrete and block work?
Based on our analysis of the mixed-use project we are working on, these systems are about 8% cheaper overall for a typical development. However, it's not a simple equation because it's the effect on the whole building process that makes it cheaper. From decreased construction time, to how easy it is for the builders and subcontractors to work with the material. It's also about 30% of the weight of concrete, so footings are much cheaper because you've got less load on them. In our case, our site had contaminated soil that needed removal so the less contaminated soil removed, the better. All these measures save money, so we actually think it’s more like 5-10% cheaper. Even if it was the same cost, the use of engineered timber will still always give you a better quality outcome.
So it reduces financial cost. What are the other benefits of using engineered timber?
Engineered Timber is a carbon sink, when you offset that compared to the effect of concrete which is a high energy manufactured product, it saves on greenhouse gas emissions and works towards ameliorating climate change.
The reduced construction duration means the building can be leased or sold much sooner
What about during the process of construction? How does engineered timber change in comparison to traditional wet trades like concrete?
The use of engineered timber means the construction process really shifts into prefabrication. Panels are manufactured off site in a factory, then brought in on a truck and assembled together on site. This eradicates the need of formwork and props that are required with concrete, which hold up the building on each floor until the concrete sets. There are also savings in not using traditional wet trades like brick layers and concreters. So trades follow each other more quickly and in a safer worksite
Savings are often also found in the reduced need for scaffolding. The panels are brought in and assembled on site, the product becomes the barriers. The timber can also be clad in the factory so that the external walls go up complete, which is akin to inserting brick slips into concrete pre-cut panels. Companies such as Robinson Bricks and PGH are doing this at the moment and engineered timber suits this application.
Pre-Fabricated engineered timber panels being installed on site
Image credit: https://www.archdaily.com/903839/worlds-largest-clt-building-provides-a-model-for-high-density-urban-housing
What does this mean for the Australian construction industry, which is famously traditional, and hasn't evolved in a great way in the last 50-100 years?
It's helping the industry to adopt prefabrication as an idea. When you develop something in a factory the tolerances are much finer, waste is reduced, and the quality control is far higher. In our industry it also eliminates some of the subcontractors who have had a monopoly on the way we build which can hold up projects and can be overpriced. Doing this means that the construction process can be more controlled. Prefabrication also has implications for the construction unions and work force health and safety. Fundamentally, it’s a much safer way to build. Those working in the factory are in a more controlled environment, and those on site are doing much less dangerous work.
What do you think this new method of construction means for the role of the architect?
Our role changes as we’re now part of the procurement system, which means getting involved much earlier. There is earlier contractor involvement or engagement, so the architect is working with the builder much sooner to design how the panels are going to be manufactured. More decisions need to be made much earlier and manufacturing doesn’t commence until all the decisions are made.
The engineered timber, manufactured in a factory rather than on site creates new and interesting ways of thinking about the build. In many ways, it falls on the architects to make decisions at the start. You can't just say, "We'll work that out on site." It’s a positive way of working because it allows the design to happen in a controlled office environment, rather than on a chaotic building site. You have the builder involved in the decision making also. They may say, "let's not do the window detail that way, let's do it another way." Quality control is likely to change also as you don't need to check that a window is being flashed correctly because it's probably going to end up being done in a factory where it’s more effectively controlled and inspected.
Read more about engineered timber in Australia:
An Introduction to Engineered Timber in Australian Architecture & Design