Hemp Building Materials

Hemp Building Materials

Building materials

Sources:  Hempcrete (HC), hemp lime spray (HLS), hemp tank (HT), East Yorkshire Hemp Company (EYHC), Thermafleece, Harrison Spinks, ISOHemp (ISH)


Hemp construction uses renewable crop-based materials which have absorbed carbon dioxide (CO2), providing an opportunity to capture and store CO2 in the fabric of buildings. It is claimed that hemp and lime can lock up approximately 110 kg of CO2 per m3 of wall. (EYHC  https://eastyorkshirehemp.co.uk/)


A whole range of sustainable building products are currently being made from all parts of the hemp plant for use in restoration and new build projects. Hemp construction uses renewable crop-based materials which absorb carbon dioxide (CO2) as they grow, providing an opportunity to capture and store CO2 in the fabric of buildings. Hemp fibre is made into 'user-friendly' recyclable loft insulation which does not contain harmful ingredients and compressed hemp shiv is used to make a fibre board but by far the most exciting development is Hempcrete, a material that can be used for construction. (EYHC)


Hempcrete provides carbon neutral, low energy, highly insulated structures and is suitable for both new build or refurbishment. (EYHC)


  • Low embodied energy - low energy used in production HemShiv for Hempcrete.

  • High embodied carbon - Large amounts of carbon locked up in Hempcrete buildings.

  • Very good thermal insulation properties

  • Good noise insulation properties

  • Breathes, helps to prevent condensation

  • Non-flammable and Self draining

  • Resistant to rodents, insects, fungi and bacteria

  • Flexible and crack resistant

  • Visually attractive - any shape can be constructed with Hempcrete.

  • Light weight

  • Improves with age

  • Recyclable

  • Sustainable - Hemp is grown every year (EYHC)

Hemp-lime composite materials absorb moisture vapour and allow it to pass through the fabric of the building; This effect is known as 'breathing walls'. Structures built from non-breathable materials can trap moisture, which is very likely to cause mould growth, particularly if there is insufficient ventilation and high levels of condensation. Breathability also helps to protect the fabric of the building, particularly against decay in the timbers. (EYHC)


Hemp is a fast-growing, low-impact plant crop that produces fine fibres suitable for insulation.  Thermafleece NatraHemp is a medium density insulation rich in home-grown hemp fibres and is a safe, efficient and durable alternative when plant fibre is the preferred choice. (Thermafleece https://www.thermafleece.com/)


We always get a few raised eyebrows when we talk about our hemp crops, but its resilience and durability make it the perfect natural fibre for our mattresses. Our hemp and flax crops produce super absorbent fibres, that help to absorb moisture from the mattress while you sleep, keeping you cool and dry. (Harrison Spinks https://www.harrisonspinks.co.uk/our-story/the-farm)


Using Hempcrete in your building creates healthy (chemical-free and damp-free) indoor environments. It is a “better-than-zero-carbon material”, locking away more atmospheric carbon for the lifetime of the building than was emitted during its construction (HC https://www.ukhempcrete.com/)


Hempcrete is a “better-than-zero-carbon material”. More atmospheric carbon is locked away in the material for the lifetime of the building than was used in its production and use. The construction industry is responsible for around 60% of the UK’s total carbon emissions, both through energy used in the construction phase and by the occupants of the building (“energy in use”). In an effort to counter the effects of climate change, the last few years has seen a ‘commitment’ by the UK government, the construction industry and its regulatory framework, for all new homes to be “zero-carbon” by 2016. (HC)

Embodied carbon is a measure of the total carbon emissions associated with a material, product or service, taking into account its extraction from raw materials, manufacturing process, transport, application, and the energy used in recycling or replacement of the material at end of life. (HC)

Because the hemp plant absorbs a very high level of atmospheric CO2 as it grows, and because the production and application of hempcrete is quite a low-tech process, the end result is a material which, even accounting for the production of the lime (a relatively high embodied carbon material), transport, and the energy use during construction, still locks away a net 110 – 160 kg of CO2 per m3 of hempcrete for the lifetime of the building. What is more, hempcrete walls have a much better thermal performance than conventional or lightweight insulation constructions, meaning that the energy used by the occupants of the building is dramatically reduced compared to conventional construction. (HC)

Damp Free:  It is “breathable” (vapour permeable) and hygroscopic: hempcrete walls and the lime or clay plaster finishes will passively “buffer” the levels of humidity inside the home, absorbing moisture from the air into the wall during times of high relative humidity and releasing it again when humidity levels drop. This eliminates condensation on the surface of the wall, preventing the conditions for damp spores to grow, and keeps internal humidity levels within the 40-60% range which inhibits the growth of viruses and bacteria. All of this is achieved without the need for mechanical ventilation systems. (HC)

Chemical free:  Because of the lime binder which coats every particle of hemp in the hempcrete mixture, hempcrete achieves good ratings for fire-, rot-, and pest-resistance, without the need for additional treatment with potentially harmful chemicals. The fact that the structural frame is set within the hempcrete wall allows for untreated softwood to be used, further reducing the need for chemicals in the home. (HC)

Staying warm and cool without costing the earth:  The extraordinary thermal performance of hempcrete – brought about by the combination of insulation and thermal mass (heat store) within the same material – means that the interior of hempcrete buildings remains at a near constant temperature with little demand on heating or cooling systems. Warm in winter and cool in summer, hempcrete homes are comfortable and healthy to live in, and help to reduce the financial impact of fuel bits on their occupants. (HC)

Hempcrete can be used as a replacement for concrete to build carbon negative, non toxic homes. The growth of hemp and the process absorbs carbon compared to concrete which releases 1.5 tons of co2 per ton. (HT https://www.hemptank.co.uk/news/upcoming-projects/)


ISOHEMP (Belgium)

The hemp block naturally regulates the temperature of the building thanks to its excellent ability to diffuse the accumulated heat. This high inertia insulating block protects:

  • cold in winter by keeping the heat in the house longer 

  • hot in summer by avoiding overheating of the habitat.

As a real thermal buffer, it maintains a constant indoor temperature and significantly reduces the impact of heat variations between day and night. Thanks to its high permeability to water vapour, the hemp block acts as a water buffer and offer a constant and healthy indoor climate for the occupants. The relative humidity level is thus stabilised (from 50% to 55%). Its uses:

  • Renovation and insulation of old buildings, old brick or damp walls

  • Interior renovation to insulate walls on which wooden floors are resting, prevent  any condensation issues in the transition areas between materials to guarantee the excellent conservation of the building

  • Humidity regulation in commercial projects where humidity variations are high: archive rooms, museums, sports halls, swimming pools ...

Whether IsoHemp hemp blocks are used for your walls or interior partitions, external and ambient noise will be significantly reduced. In terms of sound insulation, the hemp block acts as a real sound trap and helps to dampen the majority of sound waves, protecting you from noise pollution. The IsoHemp hemp block complies with current standards and provides a simple and effective solution to your site problems, both for industrial or collective buildings (nurseries, schools...) and residential homes. With an excellent reaction to fire (class A1 for the coated block), it offers up to more than 2 hours of fire resistance depending on the finish and thickness of the block used. The hemp block meets the strictest requirements of sustainable development: it is manufactured according to a very low energy-consuming process, using 100% natural materials (limestone and hemp) that are sourced locally. A very positive carbon footprint, since a pallet of IsoHemp hemp blocks stores 100kg of CO². (ISH https://www.isohemp.com/en/hemp-blocks-naturally-efficient-masonry)

HempFlax produces high-quality construction materials from industrial hemp fibre. All hemp products are guaranteed free from harmful substances, cause little or no risk of skin and respiratory irritation during installation and are extremely durable. The basis for natural comfort (HF https://www.hempflax.com/en/applications/construction/)

Negative CO2, which is very good for the environment

Highly breathable: ideal for a comfortable and healthy living environment

Temperature and moisture regulating: comfortable and easy on your wallet

Highly insulating, thermal as well as acoustic

Light weight: requiring less rigid load-bearing structures

Prevents moulding

Extremely suitable and extra effective in 'vapour permeable’ building constructions

Does not cause skin or respiratory problems, making it healthy to work with (HF)


HEMPFLAX PLUS is a high-quality insulation material made from fibre of the industrial hemp plant. A natural (and sustainable) product with exceptional insulating properties. The unique thermal, moisture-regulating properties and acoustic effect of hemp fibre contribute distinctly to a healthy and sustainable living environment.


HEMPFLAX PLUS insulation products are suitable for thermal and acoustic insulation of roofs, façades and floors in new and existing constructions. This material is the wonderful natural alternative to synthetic and mineral insulation materials. Besides traditional construction techniques, our product is ideal for timber frame constructions. When HEMPFLAX PLUS materials are used in 'vapour-permeable' building constructions, the unique qualities of this natural product become even more enhanced.