What is Hempcrete?  Hempcrete is the term used for the lightweight, insulating and breathable material produced by mixing hemp shiv with a lime based binder and water. It can be cast around a load-bearing frame (such as a timber frame) within temporary form-work or can be spray applied. It is left to set, after which time a variety of finishes can be applied. Usually a breathable lime plaster or render is used, but other options include timber cladding and masonry cladding (using lime mortar). Varying the ratio of lime binder to hemp shiv varies the strength and other properties of the hempcrete allowing it to be used as a breathable solid floor, walling system or as roof insulation.

Cast around a timber frame, Hempcrete is unique in its ability to provide excellent thermal and acoustic insulation as well as thermal mass and storage all in a single structurally sound building system which can be used as the external skin of a building. Other modern methods of construction would require several different materials, products and assemblies to match its properties and meet the many different requirements for walls, floors and roofs.

Hempcrete creates healthy, breathable buildings, it can absorb and emit moisture vapour which helps to regulate internal humidity and prevent trapped moisture and toxic or black mould growth, ensuring a healthier indoor climate.

                        

Costs:  The costs of Hemp-Lime building are comparable to those of conventional construction and in many cases, due to  the lightweight structure requiring less substantial foundations, Hempcrete has been a more cost effective alternative. Visit our gallery page to learn about a kitchen extension where this was the case.

Advantages of using Hempcrete- 

  • Hemp transforms COduring its growth by capturing carbon and releasing oxygen. Using Hemp in construction locks up the captured carbon for the life of the building. Approximately 110kg of CO is locked away per cubic metre of Hempcrete.
  • Hempcrete is highly insulating with very low U values, resulting in an energy efficient building, ideal for meeting today's higher building standards.
  • Hempcrete is a way of providing thermal mass. This means that hempcrete buildings will change temperature more slowly and reduce heating loads compared with lighter weight building materials with similar U values.
  • Hempcrete can be sourced from within the UK using renewable UK grown hemp.
  • Hempcrete is natural and vapour permeable (or "breathable"), helping to facilitate healthier buildings.
  • Hemp can be grown in rotation with food crops to improve the soil and reduce weeds, it does not require agrochemicals in its cultivation and there is no need for pesticides or insecticides. The Hemp shiv used in Hempcrete is a low-value waste product of the hemp fibre producing industry.

Learn more about Hempcrete:

  • Purchase a copy of Hemp Lime Construction by architects Tom Woolley and Rachel Bevan or a copy of Tom's new book Low Impact Building which is a comprehensive guide to the designs technologies and materials that make truly sustainable buildings work.