One of the glorious benefits of wood is its flexibility to be used innovatively in building. Modified wood may not be a familiar term, but this durable building material is being used in homes, commercial and public buildings and external settings around the world.
The term modified wood describes wood products which have been modified through treatment with a chemical, biological or physical agent to enhance their performance.
What differentiates modified wood from traditional wood is how its modification increases durability, making it ideal for external cladding, decking, outdoor furniture and much more.
The most common species of wood used in the modifying process are radiata pine, ash, sycamore and poplar.
Accoya creates a durable, non-toxic, dimensionally stable material through the chemical modifying of plantation grown softwood such as radiata pine. It’s mostly used for external cladding and wood siding, external decking and joinery, but Accoya’s project portfolio showcases major achievements using this pioneering material including the restoration of a battleship!
Norway-based Kebony manufactures a sustainable and durable version of modified wood, also from species such as pine, replicating the characteristics of hardwood. It’s mostly used for decking and cladding but has also been used for swimming pools, at seaside properties and in countries facing harsh weather conditions such as its home country.
ThermoWood by Metsa Wood is produced by heat treating Finnish grown pine and spruce to temperatures in excess of 200 degrees centigrade. During the heat treatment, chemical and structural changes occur within the timber which alter and improve some of its basic characteristics. The resulting product is more durable and stable timber, an ideal cladding material for use in exposed areas such as external walls.
Tricoya, a product made by Medite Smartply, is a more durable and stable version of the traditional MDF panel. Tricoya can be cut, painted and wrapped without compromising its durability and stability. It’s mostly used on door skins and door panels, façade panelling, trim, fascias and soffits.
British-based Brimstone is created from fast-growing hardwoods such as ash, sycamore and poplar which are grown in Britain. It is made differently to other modified timber as it uses wood thermal modification technology, meaning that it is super-heated in a controlled, oxygen-depleted environment. This creates a stable and durable product, ideal for external cladding, decking and outdoor furniture.
The science behind modified wood has enabled it to break into markets that were often untouched by the timber market, lending itself to unlikely projects such as canal lining, a penguin bridge in an aquarium and an external climbing wall, all normally created with materials such as stone or concrete.
Modified wood provides extra strength, resistance to fungi and rot, and is indigestible to termites. It retains the warmth that traditional wood products contribute to harsh exteriors or features made from stone, concrete, brick or steel.
Building on wood’s natural pleasing aesthetic, the Shou Sugi Ban method produces charred versions of Accoya, Kebony and Yukari cladding – a modern form of the ancient Japanese art of charring wood. The traditional craftmanship is combined with modern techniques to ensure the wood is charred evenly. This creates a fire-retardant carbon layer and a striking aesthetic.
In addition to being a visual enhancer, modified wood brings many other benefits. It is a sustainable product, locking in carbon and contributing to the circular economy with most modified wood products using cradle to cradle design. This was the reason that Bangaroo House, a three-storey restaurant project in Sydney, Australia, chose Accoya modified wood. Sustainability was at the heart of the project and combined with Shou Sugi Ban, the outcome is a stunning piece of architecture. Should it ever need to be deconstructed, the modified wood can be recycled or reused, creating zero waste.
In its recent report “The Future of Sustainability in Design: Rising Trends in 2018 and beyond”, Kebony looks at smarter wood products and how modified wood has impressive longevity. Kebony states that “the desire to create more environmentally-friendly structures has naturally been affecting not just how homes or commercial building are designed, but also has prompted evolution in build materials themselves.” This reinforces the sustainable benefits modified wood can bring to the world of construction.
Alongside modified wood’s sustainable benefits are the health and wellbeing advantages. Wood is renowned for its calming qualities, a decreased perception of stress, a decrease in blood pressure, improved air quality and generally a heightened feeling of comfort. None of these advantages are lost in the modification of wood. Modified wood is also non-toxic, making it popular in nursery and school settings.
Wood is an ideal material to use to help reduce energy bills. A housing association in the West Midlands wanted to provide affordable housing for its residents and were concerned about the level of fuel poverty among their tenants. The architect, Architype, suggested building using Passivhaus principles to overcome this problem and they chose Brimstone to clad the homes. Not only is the cladding a hardwearing product, it assists in reducing energy bills and helps to make the homes more comfortable.
Modified wood is one example of how the timber industry is using science and engineering to keep refining this natural material. For this reason, modified timber has a dedicated chapter in Peter Wilson’s book, The Modern Timber House in the UK, New Paradigms and Technologies, published by Wood for Good in 2017.
Timber advocate and architect, Peter Wilson, explains the methods and benefits of modifying wood before exploring an array of incredible case studies that showcase using modified wood for affordable homes and private projects.
Download or order a copy of the book here.
How to specify modified wood products? Read our interview with Gordon Ewbank, Wood Protection Association.
Find more case studies on modified wood.
Images: Barangaroo House by Rory Gardiner