Hemp Building Workshops at Mountaintop

A series of hemp building workshops are being hosted by Auntie Liz Johnson at Mountaintop, N.S.W.

Auntie Liz on-site at Mountaintop

Klara Marosszeky is teaching people from around the country how to mix and build with hemp and a lime based binder, with participants working on a building for an Aboriginal Cultural Field Study Centre. She has been working with hemp for 11 years as a licensed researcher and grower and developed this Australian hemp-lime building material at the University of New South Wales where it underwent testing at the Centre for Construction Innovation.




Klara at recently completed Billen Cliffs hemp home.
www.hempmasonry.com

  The two women work together as teachers at TAFE as well, and these workshops are about sharing information about building healthy homes and the opportunities for communities to grow industrial hemp for housing.

Industrial hemp farming takes up about 10 tonnes of carbon from the atmosphere per hectare in about 4 months and hemp houses lock that carbon up, through a process called carbonation. The fibre of the hemp plant and the lime based binder react together to form a masonry product which gets harder and harder over time.  No kiln baking is needed. So compared to most other building materials which use a lot of energy to produce, hemp building is not energy intensive.

Hemp construction is being used  for social housing projects in England. The main thing holding back the industry in Australia at the moment, is that there is still a shortage of hemp available as its a very new industry.


Two workshops have been held so far at Mountaintop. The first was for people from around NSW and Queensland who had been on a waiting list for a hemp building workshop to be run. The second was for Aboriginal builders and labourers.

During the day the focus was on building and in the evening there was a session on the licensing system for the hemp industry and how to apply for a licence and on farming and processing  hemp for building materials.

Workshop participants learnt about how to mix the materials and operate a pan mixer. 

They also learnt about putting up the formwork around a pole or stud frame and how to fill it to get lightly tamped or packed walls.

On the Saturday of the first workshop a hemp floor was put down.

 The floor was laid onto a gravel base that was boxed in with blocks that had been core filled.

Hemp floors are commonly used in hemp buildings in the U.K. This floor is a research project based on the U.K models. As far as we know it's the first hemp home in Australia with a hemp floor. It will be monitored over time, and data will be collected.

Tamping the hemp floor

On Sunday formwork was set up for the walls. The hemp mixture is tipped into the space between the formwork and tamped down gently to build the walls. The first layer was built all the way around the building, leaving space for doors.

On Monday the formwork was removed from the walls, allowing the carbonation process to begin.

This photo shows how the material is packed around a doorway ready for installing the door jamb.

The floor and walls turned out looking great.

This floor has not yet been fully laid. Once the walls are completed any loose material will be removed, re-mixed with binder and sand and re-placed. The existing floor will be then be slightly dampened and hemp will continue to be laid in 50mm layers and tamped until it is level with the small deck. The likely finish is a sand lime screed.