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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.

Using the woody core of the hemp plant with a lime binder to make a biocomposite called Hempcrete, that can be cast or sprayed into the walls of newly built houses. Hempcrete is a non structural wall infill to be used in conjunction with timber frame structures. Hempcrete walls provide all the insulation the building needs. Floor and roof insulation can also be achieved with the hemp lime biocomposite.

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

Hempcrete is also a very good choice for renovating many old buildings with poor insulation where a layer of Hempcrete can be applied to the interior of the building providing some insulation and eliminating drafts. In some circumstances the Hempcrete can be applied to the outside of the building to achieve the same results.

The process of turning hemp into houses is not at all complex. Hempcrete is simply hemp shiv combined with natural lime and water as binding agents. This creates a creamy mix which is then poured into removable wooden shuttering and lightly tamped down to produce a 300mm wall cast around a timber frame which provides the load bearing structural stability.

Hempcrete buildings have many good properties some are listed below:

    Low embodied energy - low energy used in the production of 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 making it virtually earth quake proof.

    Visually attractive - any shape can be constructed with Hempcrete.

    Light weight.

    Improves with age.

    Recyclable.

    Sustainable - Hemp crops can be grown up to 3 time every year.

How is it better for the environment?

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.

Breathability

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.

Hemp and lime masonry construction is unique because it provides a method of building which is structurally sound, can provide thermal and acoustic insulation, thermal mass and storage but can also be used as the external skin of a building. It is extremely simple to construct, using just one method to meet many very different requirements for walls, floors and even the roofs.

The characteristics of hemp concrete provide great health benefits. Hemp, unlike other materials such as wood sawdust, does not release dust, so it does not come into contact in the air and therefore, does not produce allergies.

As it is a transpirant material, it does not retain moisture, it releases both water and water vapour, and makes sure the rooms are continuously recycling the air and expelling moisture and odours.

Unlike other materials like wood, hemp does not contain proteins, so the animals do not attack it. In addition, hemp has a protective effect against electromagnetic radiation from cell phones and masts.