Hemp Architecture—Beautiful, Eco-Friendly and Fire Resistant

Figtree Hemp House near Byron Bay, by Balanced Earth Architects
Photography: Andy Macpherson

A striking red oxide wall, created by the clients shows off the exposed, coloured hempcrete.
In the sub-tropical climate, the breathable material counters the humidity and any mould.
There is natural cross-ventilation and no air conditioning.

Building with hemp is growing in popularity, from public buildings in Tasmania to private homes in Byron Bay, with architects looking to more sustainable materials in one of the world’s most carbon intensive industries. With the ability to capture more than twice its own weight in carbon, purported insulation, moisture- and fire-proof qualities and now with a hempcrete building winning a National Architecture Awards nod, the eco-material is cementing its place in modern construction.

Hempcrete is carbon negative. Hemp takes just 100 days to grow. It has regenerative benefits for soil and is used in a range of industries, from building to textiles. Once the crop is harvested, the stem – known as hemp hurd – is processed (also known as retting), leaving woody fibres that are shredded and crushed to size. To build, it is most often mixed with lime-based binder and packed into the timber wall frame.

Hemp is most commonly built “in situ”, packed into the wall frame, but opportunities are also arising for it to be used in prefabricated blocks and panels, pre-packed and delivered to site. It can eliminate the need for timber studs (part of a wall frame), bulky insulation and often synthetic wall linings. Lime render is added, as well as a sealant, to ensure waterproofing.

At the Australian Hemp Masonry Company, the Managing Director, Klara Marosszeky, promotes the possibilities of the material to architects, builders and owner-builders. “It’s really quite light to work with, and it is owner-builder friendly” Marosszeky says. “The expense in building hemp houses is generally in the labour component of it, much more so than in the material”. As specialists are typically required to install hempcrete walls, new projects such as the University of Tasmania’s forestry building and the Lithgow Women’s Shed, a community-led project designed by Envirotecture and using hempcrete for it’s walls, are proving the material has some traction.