Forms of Hemp lime construction have been used for centuries. The hemp hurd or shiv when mixed with a lime binder forms a light weight aggregate. The lime is antiseptic and antibacterial and the highly insulative composite material is fire retardant.
The material’s flexibility allows it to be used in a number of ways in addition to new construction. For example retaining the frame but replacing poorly insulated composite external walls can be a good option in retrofitting for energy efficiency.
A lighter form of the insulative walling material can also be used for roofing and subfloor insulation.
Buildings made of hemp:
store the carbon from a renewable biomass throughout the life of the building material
create a vapour-permeable construction envelope that ensures healthy indoor air quality
provide excellent thermal insulation and some thermal mass
avoid thermal bridging and provides good airtightness with simple detailing
are simple to construct. Hemp building requires care but the skills are easy to learn.
reduce the load on foundations because it is light weight material
can have zero waste, as previously mixed material can be reintroduced in controlled proportions to new mixes.
For optimal durability once dried, exterior hemp walls should be finished with a Hemp lime, Lime or other natural render or breathable finish. Other than this hemp lime needs no unusual protection from the elements.
As with all lime based construction materials, to ensure a quality build Designers, Contractors and Owner Builders require a high level of understanding of the product. AHM offers formal training and hands on experience through regular Hemp Building Workshops.
Source: Hemp Masonry