The Recycled Interiors Podcast 007: What the Heck is Hempcrete?

Today on the Recycled Interiors Podcast, we are chatting with Greg Flavell from Hempcrete International, all about Hempcrete – what the heck is that you may ask? Well today you are going to find out!
Listen and subscribe on iTunes here and Stitcher here
Born 1959 in New Zealand, Greg Flavall graduated High School in Vancouver, Canada. Greg pursued a career in building, learning all facets of construction, later moving to California where he partnered with a friend to start a General Contracting company. 2005 saw a change of direction for Greg when he learned about the many benefits of Industrial Hemp and it’s applications, particularly in regard to construction, to reduce the CO2 emitted from mineral based building products and to increase indoor air quality.
In 2008 Greg co-founded Hemp Technologies (USA) Inc. in Asheville, NC, to build healthy, energy saving homes with Hemp+Lime. Greg is a qualified Chef, plays Scottish BagPipes and enjoys golf, tennis, fishing. and family time.
For those of you interested in alternative building materials, this is a fantastic episode. Enjoy!

Things you will want to remember from the episode

  • When we grow Hemp for these purposes it is the fibre only variety
  • It is separated and then you get a material like a wood mulch, or balsa wood chopped up, which is hydroscopic – which means it is breathable
  • Hemp is then mixed with lime – used on a house this is highly breathable which creates a healthier interior. Hempcrete is the hemp cellulose mixed with lime as a binder, which protects the vegetative cellulose from rotting down – basically coating the outside of the hemp cellulose
  • This is then cast around the structural frame of a house to create the thermal mass
  • It is cast in stiu – you have the structural membrane (timber frame) and you put up temporary shutters ranging from 250 – 300 mml thickness depending on the climate, the hemp/lime/water mix is then cast into the frame and when you take the shutters off, you do not see the frame anymore
  • Unlike concrete only a little water is used and takes less time to dry out
  • A render is then added to the outside and can also be used on the inside if you want to – note building codes will not allow you to leave it unrendered in many countries, including Australia – a layer of 12 – 20 mml lime plaster is generally used which is also breathable
  • The walls of the hempcrete and lime mix assist with the take up of CO2 produced in your home – the life cycle of the lime means it will absorb the CO2 in your home – it is a living breathing material, creating a better indoor air quality
  • Studies have shown that inhabitants had up to 70% reduction in health care and absenteeism from work
  • A brewery near London used 500 mml thick walls and a living roof, and they saved $600,000 US in not having to do any heating or cooling – maintains 15 -17 degrees Celsius to keep the beer cool!
  • Hempcrete is also moisture regulating – a car museum used it to prevent rusting of the antique cars
  • Australia building regs mean we need a cavity system for the walls as they are worried about moisture penetration – hempcrete is a solid wall system. There is no facade or air gap. This makes it tricky to get permission to build a hempcrete home
  • In NZ they have just got a permit to build a home, which is paving the way for more permits there. Similar challenges exist in Aust -a distributor in WA exists but they are having the same difficulty. However it is a matter of educating councils about the benefits of building in this way and demystifying the use of hemp
  • More than 25,000 products are made from hemp!
  • Fire rating is very high – the lime sweats as it gets hot and creates a self fire retardant. Fire testing at 300ml thick showed an hour and a half before setting. This means reduced fire insurance in the states and it is potentially going to be the same here
  • Termites don’t like lime – bonus!
  • If you want to start a project in Australia, you can contact Greg and he can help you take it from there
  • On average the costs of a hempcrete home are about 10-15% more expensive upfront but by the time you move in, it will come in at the same price as a traditional build
  • There are savings also because you do not need any heating or cooling (although many people still add depending on your climate – and often find they don’t use them). Reduced energy use is high – it is not just about the cost of the build but the ongoing savings
  • Builders are trained by Greg and his team – they do onsite training when a build is happening, owner builders can also do this – keep an eye on the website for any upcoming in Australia as this is going to increase
  • Also keep an eye on Grand Designs Australia towards the end of the year for a build Greg is doing at the moment!

Would you consider building a hempcrete home? Or have you been involved in a project? I would love to know your thoughts, and questions so please drop them in the comments. Also please leave a review on iTunes and Stitcher to help spread the word.
Thank you
x Helen


Hemp Technologies
Hempcrete Australia


  1. Terry Crawford on September 16, 2016 at 8:16 pm

    A first for Coolum maybe, Amanda Crawford ?

  2. Amanda Crawford on September 17, 2016 at 3:23 pm

    I’d like that dad! xo

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