Hempcrete Factsheet

Posted on by Tom Abbott

Hempcrete is a combination of chopped hemp shiv and binder comprising of natural hydraulic lime and a small amount of cement. It is firm and self insulating. Hempcrete is suitable for uses such as timber frame infill,
insulation and, with the addition of aggregate, floor slabs. Hemp is a renewable biomaterial and lime is an abundant quarried material.

Hempcrete regulates the temperature and humidity of a building; in some cases completely eliminating the need for heating and cooling systems, resulting in huge energy savings. Hempcrete is carbon negative and the obvious choice for buildings aiming to achieve a low carbon footprint and the highest sustainable building code levels.

Hemp has been grown in East Anglia for hundreds of years. The carbon trapped in the hemp offsets the carbon not only of the hemp production but also the residual carbon from the lime production after re-absorption of carbon as the lime cures.

Being breathable, hempcrete is ideal for use in historic buildings and modern buildings using natural materials. Breathable buildings bring benefits for the health and comfort of the occupants.

Our team regularly batch and place 20m3 of hempcrete in a day. Our specialist reusable plastic shuttering can be stripped from walls the following day to allow the hempcrete to dry and cure. In fair weather conditions we apply lime based render after 4 weeks and top coat 2 weeks later.

Facts and Figures

We are very grateful to Lime Technology Ltd for allowing us to use this data for Tradical® Hemcrete®

Density 275kg/m3
Flexural Strength 0.3-0.4 N/mm2
Thermal conductivity λ=0.06W/m.K
Heat Capacity 1500-1700 J/kg
Mean Acoustic Absorption Coefficient 0.69 NRC
Air Permeability 0.75 gm/m2/mm hg
Vapour permeability 24.2 gm/m2/mm hg
μ Vapour Diffusion Resistance 4.84
Fire Rating 1 hr BS EN 1365-1:1999
Carbon capture 130kg CO2/m3
Airtightness <2m3/m2.hr@50pa

Applications

  • Walls – Timber frame infill
  • Insulation – Retrofit against existing walls
  • Floor slab

29 thoughts on “Hempcrete Factsheet”

  1. I am involved in light weight steel frame construction in South Africa and believe that this is an alternative option for outer cladding or off shutter infill using the steel sub frame as the loading carrier
    Has this done before ?
    Are there any building methodology statements ? Or alternative certifications that have been tried
    I would love to participate in taking this to market or researching further

    Find it extremely interesting and would like to do further investigation
    Can we get into conversation ?

    1. We would need drawings and elevations to understand the scale of the job. Please get in contact via email.

  2. Here in the US, the are sometimes homes with brick siding instead of full brick exteriors. Would there be a hempcrete version of that, and can your available products be used here in the US? Is the hempcrete usable on exteriors or on outdoor projects, such as brick garden wall or raised garden bed? It just seems like this product would be more environmentally friendly than traditional bricks.

    1. Hempcrete can be used for insulation of walls or for the actual whole wall itself. The walls are reliant on timber frames and therefore may not be so useful for garden projects.

  3. Recently, DEA/Customs allowed the importation into Kentucky of 250 lbs of industrial hemp seed for experimental farms under academic supervision. Congress has pending bills allowing cultivation of Cannibus Savitia L. I see industrial hemp as a great fiber. There is a UK company whicy makes a retting machine. Can you furnish me a lead to find this company? Thanks.

    Jim Mioler

  4. I would like to build a mobile mini eco hempcrete house on a trailer like many others taking there homes on the go. Do you think I can build a mobile home from hempcrete that’s light enough for a car to pull. Side note I’d like most of the house to be enviromently friendly and sustainable. This means useing the hempcrete for countertops or bathtub and in the green house. Maybe even change the house shape to reduce air drag. Thanks for reading!

  5. Your technique is marvelous. My thoughts have run parallel to the other iquirer. Steel frame and hempcrete seems to be well suited for each other. Is there any chance you may venture to add a division in the US?

  7. We are a community land trust group, self building 14 post and beam, straw bale wrap affordable homes with a district heating system on Dartmoor National Park. We are looking for an economic and eco slab to house underfloor heating and support the frame and bales.
    Is Hempcrete the answer?
    Can we use recycled concrete as sub structure for the hempcrete and reduce the expensive amount of Formglas or Leca blown clay needed?

    1. Sorry for the late reply. Limecrete flooring would be more suitable for this and the best form of insulation is the Glapor foamed glass. Please email us if you would like a quotation.

  8. hi there/
    can hempcrete be used in cavity walls as insulation?

  9. i am in dental school and i wanted to know if there could be applications in the dental setting we use alginate and hard plaster stone to make models and cavity preparations and i was just wondering if anything like that is possible or being tested?

    1. We are unaware of any applications for limecrete or hempcrete in the dental setting. I am not sure it would be economically viable on such a small scale.

  10. What standardised amount of hempcrete is used to to get the results of the different ‘facts and figures’?
    Thanks!

    1. You would need to spray metal protecting paint; red oxide primer before spraying hemp to stop any corrosion.

  12. I live in south west France and have a timber framed external wall infilled with hempcrete. The wall was completed in February this year, but we are unlikely to be able to have it rendered before winter. Can you tell me if the hempcrete is likely to be damaged by frost and if so, what measures can we take to minimise this?
    Thanks

  13. how structural is it. I’m a former brick/block mason for 16 years, now in rolled in college.You don’t build buildings with brick, brick is just curb appeal.The block that’s layed behind the brick and that has re-bar running verticaly and horizontally through it, is the strength of the building along with the concrete footing..And the brick you show is a standard brick, has no holes, is pretty much good for nothing.

  14. Can you lay a screed over the hempcrete and would you introduce a VCL instead of a DPM at all?

  15. Six years later and this article’s information is still accurate. The only difference is now the awareness of hempcrete / hemplime / limecrete as a building material has significantly increased.

    We are located in the United States and there is a real want and need for building with hemp. Unfortunately, we are so far behind Europe and we are lacking the proper accreditation and build code standards to really see the material take off within our green building niche.

    My hope is that consumers continue to educate themselves on the amazing benefits and start asking for their homes to be built with it. As a result, the ASTM and ICC would feel a bit more pressure to come up with certification and standards.

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