The Whole Hemp House

by Warren McLaren, Bundanoon, Australia
hemp masonry cottage photo

All Photos: The Hemp Builder
The house you don’t need to render, plaster, paint or insulate. The house with the building material that you can grow on one hectare (2.5 acres) of land. The same building material you can process yourself with standard machinery available at your hardware store. The house whose walls lock away over 110 kg (240 lb) of carbon per cubic metre.
Impressive claims. What is this boastful house made of? Hemp. The whole hemp. We’ve talked before about hemp bales, and even hempcrete. But this appears to be something new.

Two years ago we wrote about Klara Marosszeky‘s ongoing research to produce an easily worked building material based on Australian hemp. At that time she was concentrating her work on the hemp hurd — the pithy centre of the stalk — but that proved too costly to separate from the bast — the tough fibrous sheath of the stalk, in a process known as decortication.
But now it seems Klara has hit on a way to use the whole of the stalk and mix it with lime plaster to create a hemp-based, building masonry material.
When interviewed in the Echo News earlier this year, Klara Marosszeky observed that, “Using hemp masonry to build also means you are using a low embodied energy product because you don’t have to fire them like bricks. You can effectively build a house in four days.”
From what we understand, the hemp/lime mixture is then pressed into formwork, as in-fill between a timber-framed structure. As it hardens it becomes a solid, yet ‘breathable’, insulative, masonry-like wall substrate, such as Klara is leaning against in the next photo.
Hemp House Klara photo
In order to promote this form of building material Klara has teamed up with Paul Benhaim to offer an electronic book called Build A House Of Hemp. Although the technology behind this new hemp material is no doubt very sound — Klara has been researching this for 10 years, and building her own house with it — the website promoting the book does lean towards the late night infomercial end of the marketing spectrum.
Klara and Paul are also planning to run a series of workshops on the topic, starting with one this week in Byron Bay, NSW. This is expected to be followed by workshops in Canberra, Sydney and Cairns in 2011. It looks as if Boulder, Colorado and Ontario, Canada are also on the workshop tour.
We can only hope this building methodology takes off, and Australia finally has a real economic pipeline for a local hemp agricultural industry.