Let’s Talk About Hemp & Other New Environmental Building Materials.
Updated: Oct 28
It’s Time to Look at Alternative Building Materials
Australia is in the middle of a building materials shortage, the likes not seen for some 40 years. Although steel, cement, kitchen materials, paints and some electrical components are running low, timber is causing the most headaches.
Australia, like many countries, centred on the construction industry for economic recovery during the pandemic, so international supply chains were strained. And, while pandemic stimulus packages increased demand, incessant bushfires throughout the country impacted our local timber supply, destroying thousands of hectares of softwood plantations. That will impact the local market for the next 12 months or longer.
So it’s a good time to talk about alternative or new products that are emerging in the building design industry, that make for a sustainable and environmentally friendly future for the industry.
From recycled plastic and reclaimed wood through to bamboo, cork, hemp and more, there’s a whole raft of products and materials that are increasing in uptake for sustainability of the builds and the industry.
Let’s Talk About Hemp
Cannabis sativa or hemp is one of the oldest plants on earth, having been discovered by archaeologists in fabric traces originating from Mesopotamia in 8,000BC. It’s believed that Christopher Columbus’ ships' ropes and sails were curated from the fibres, and Rembrandt and Van Gogh used hemp oil paints and hemp canvases.
In architecture, hemp was found in the mortar of a stone bridge from the 6th century, in the area now known as France, and the Romans used hemp fibres to reinforce structural mortar.
Hemp is one of the most durable raw materials, requiring little water to thrive around 50 times faster than a tree. It’s a magic plant with many uses.
So what’s not to like right?
Hempcrete – aka hemp masonry – is a composite material of hemp hurd (the inner woody part of the plant’s stem), lime binder and water. Sand is sometimes added to the mix to reduce the lime binder and add some thermal mass.
It’s gaining popularity in the building and design industries, because it ticks so many boxes as a building material:
It’s extremely lightweight – so reduces the load on foundations
It regulates temperature – so is energy efficient
It absorbs moisture (hygroscopic) – so regulates humidity and prevents mould
It offers acoustic control
Hempcrete is completely bio-based – so can offer zero landfill, and offers a zero carbon footprint
It is durable and long-term crack free – so while a little more expensive than bricks and concrete, offers investment value
Is fireproof and termite resistant.
It’s not suitable for structural bearing elements, but due to its thermal benefits is a perfect solution for walls and roofing.
Its eco-friendly footprint, value and versatility should see it become a staple of modern housing and building solutions in Australia for the future.
Bamboo is strong. Tests have shown that it has better tensile strength than reinforced steel, enabled by the tubular shape which is wind and earthquake-resistant.
Bamboo has traditionally been used for centuries as a structural material where it grows natively. It’s still in use as scaffolding and for housing in areas of Africa, Oceania, South America and Asia, and there’s increasing interest in it for Australia’s tropical areas.
It’s also cheap, pliable, harvestable in four years and grows in places that other plants don’t, so it doesn't need to encroach on crop-growing areas.
It offers efficiency and sustainability, which means a shift to bamboo composites replacing steel in structural reinforcement can reduce the carbon footprint of the building industry.
Bamboo’s flexibility can also enable strikingly beautiful results with the right design team.
Outside of being the humble bottle-stopper, cork is also steeped in history; ancient Egyptians, Romans and Greeks used cork for building insulation, footwear and for floating their ships and fishing nets.
Cork oak tree bark is stripped every nine years – the trees aren’t cut down, and cork forest trees can live up to 300 years. It’s chemical-free, fire and water-resistant, sound absorbing, has antimicrobial properties, and it’s fully recyclable.
Outside of the obvious treatment of flooring, as a great insulator, it can also be used for cladding and in roofing.
Almost every building and home design project uses wood, so there’s no getting around it. While timber or wood is viewed by many as a renewable resource that stores carbon, it’s undeniable the damage deforestation is doing to the planet.
Recycled and reclaimed wood is the most environmentally friendly way to work wood into building design. Think salvaged wood planks from barns, flooring and beams from old houses and factories, old wooden fencing and driftwood.
Wood adds character and warmth to any space, and its applications are limited only by imagination; mantelpieces, door and window framing, exposed beams, ceiling panels, kitchen cupboards and benchtops, accent walls or a beautiful old barn door to separate spaces.
However, wood is susceptible to water and pests such as termites, so getting expert advice is recommended.
Around 400 million tonnes of plastic is produced globally each year – and only 9% is recycled. It’s virtually indestructible – naturally – in the environment and is causing catastrophic damage from the bottom of the oceans to the peaks of our highest mountains. Plastic is an unsustainable material.
So extracting plastic waste from the environment is a viable solution, and recycled plastic is a sustainable building solution in two ways: plastic waste can be used to make ‘green’ concrete, and it can substitute for high emission building materials like bricks and steel. The lightweight material equates to easier transportation, handling and installation, and it maintains its mechanical (strength) properties and has a durable shelf-life.
Europeans are already working with it in the building and construction sector, with almost 50% of their post-consumer recycled plastics applied in building materials for things like bricks, curbstones and fencing.
Green Building & Design is the Future
The bottom line is our planet cannot sustain the amount of waste and emissions that occur using traditional materials, particularly in the construction and building sector. Architects, builders and designers need to be more innovative in their approach to their craft.
Outside of embracing recycled and repurposed materials in your build, there are other considerations to designing a green home, such as energy and water efficiency, waste reduction, and indoor and outdoor environmental quality.
Reusing, recycling, and upcycling is not only viable, it’s necessary for the sustainability of the builds and the industry – but more importantly, for our health and the health of the planet.