Materials (Timber)
In keeping with overall sustainability strategies, ideally the choices of building materials are the most sustainable possible. In this article, we examine timber (and the many timber product variations) and look at the way forward for this very fundamental building material.
An important starting point in any consideration of building product is the need to understand why the material (in this case, timber/timber product) is being used. For example, is there a way of creating the design so no material is needed in the first place? Can the timber be used for several purposes in the design? Can timber be used in lieu of a man-made material?
Another critical question to consider is where was the timber (or engineered timber product) sourced and manufactured? Ideally, priority should be given to locally sourced materials. Suppliers and manufacturers should be committed to sustainability and making ethical choices. In all building materials choices, it is important to consider the sustainability credentials of the manufacturer and/or supplier. For example, do they comply with local and national industry standards? Do they support their local community? Is the timber or engineered timber product’s transportation from origin to site energy efficient? Is the packaging of the material recyclable?
At the same time, it is also important to consider how using timber or timber products can add value to the project. Will the building owners enjoy long-term value from using timber in their project? In adding timber to the project has the designed been enhanced in ways that could not have bene achieved if timber wasn’t used?
There are a number of timber and timber product options available today for use in building design.
Traditional Timber
Timber has a lower carbon footprint compared to other traditional building materials and indeed is one of the few renewable materials that can contribute to the reduction of carbon emissions. Trees actively take carbon from the atmosphere while growing, and when they are cut down for use as building materials, the carbon is ‘trapped’ and unable to escape into the atmosphere as carbon emissions.
Timber also has several other environmental advantages:
- Particularly where it is locally sourced, timber uses relatively little energy to convert from the raw material to a building product in comparison to other structural materials such as steel and concrete.
- Because it is lightweight and versatile, timber is typically easy to handle and install. This facilitates a faster and less disruptive construction process with reduced construction costs and energy consumption.
- As a naturally insulating material, timber can create a barrier between hot and cold. In particular, where focus is given to energy efficiency, the use of lightweight timber can greatly contribute to maximising comfort and minimising non-renewable energy use.
- Even though it is combustible, timber is slow, predictable and measurable in the way that it burns which means, compared to other materials, it actually performs strongly in fire events given its natural fire performance capabilities.
Where the timber is sourced from is very important. Ideally when choosing it is best to prioritise timber as follows:
- Australian recycled timber (great for building walls, cabinetry, decks, floors, beams, panels and other structures)
- Australian Forest Stewardship Council (FSC) and chain of custody certified timber (trees are renewable but forests are not)
- Australian Australian Forestry Standard (AFS) and chain of custody certified timber
Responsible forestry and sourcing of timber and timber products is an essential part of the solution to reducing harmful carbon emissions. Accordingly new timber sourced from non-FSC or AFS accredited forests should be avoided.
In addition to the source of the timber being used, other elements to consider include choosing to use mechanical fixings, avoiding adhesives and finishes that might create unnecessary maintenance issues. These choices also make it easier to recycle the timber at the end of the building’s life. Timber which has been glue-fixed can be almost impossible to later recycle.
Engineered Timber
There are a wide variety of engineered timber products available to be used across building projects. Typically an “engineered timber” product has been created from different types of timber and derivatives of timber combined with some sort of binding agent (as opposed to solid pieces of timber from a single source). The intention is to create a stable and economical product. Common engineered timber products include plywood, MDF, particle board, laminated veneer and cross laminated timber (CLT).
Many of these products can be an efficient use of natural resources. The manufacturing process can utilise otherwise unusable smaller cuts or lower grade timber and produce a product that is stable and strong.
In choosing engineered timber products it is important to choose locally manufacturing products or manufacturers that hold carbon neutral certification.
As is the case for traditional timber, it is important to avoid engineered timber products that contain timber sourced from locations where responsible forestry cannot be guaranteed.
In many cases engineered timber products have excellent strength and stability and offer decent fire resistance. Typically, because the panels arrive on site prefabricated, there is less waste on building sites.
Engineered timber flooring
Engineered timber flooring is made by fusing a thin layer of hardwood and bonding it to several layers of high-quality plywood with extreme heat. The end product is a strong, durable flooring option. Because the top veneer is solid timber, the product still has the look and character of solid timber flooring. Depending on plank thickness, scuffs and scratches can be fixed through sanded and resanding.
There are additional energy resources required to manufacture some composite timber products. Re-processing composite timber products is possible, however, the glues and other adhesives in the composition and fixing of composite timbers can hinder recyclability.
Timber and Commercial Projects
Timber has traditionally been considered primarily as a building material for residential projects. However, advances in design and technology have seen an uptake in the use of timber and timber products in commercial projects. In particular, the advent of CLT (cross laminated timber) has resulted in an increasing number of commercial developments choosing timber as a viable building material.
CLT is created by layering planks of sawn, glued timber, where each layer is oriented perpendicular to the previous. Because of the perpendicular angles, structural rigidity for the panel is obtained in both directions, similar to plywood but with thicker components; giving the product tensile and compressive strength. It is this strength that means CLT can be used, in certain cases, as an alternative to concrete and steel for all or part of a building’s construction.
Current issue - Social sustainability
PEFC, the Programme for the Endorsement of Forest Certification, is an international non-profit, non-governmental organization, dedicated to promoting sustainable forest management through independent third-party certification.
As a direct response to the aggression against Ukraine, PEFC has declared that all timber originating from Russia and Belarus is ‘conflict timber’ and therefore cannot be used in PEFC-certified products. This also applies to all timber originating from occupied Ukrainian territory.