Hemp masonry infill is a relatively light, non-structural material with excellent acoustic and insulation values but a relatively low structural strength. The AHMC construction method uses the hemp infill as a non-structural infill.
All vertical and lateral loads on the building itself are borne by the timber frame which must be built in accordance with “AS 1684.1 Residential framed timber construction” the timber framing code or engineered if the design deviates from the provisions of the standard. In this instance the building must be certified by a structural engineer.
The framework in hemp lime masonry construction can be timber, concrete or steel. Lime is an alkaline substance which does not corrode steel if kept dry and it also preserves timber protecting it from rot and insect attack. With steel framing, as a precaution a bitumen-type coating should be applied to the steel, as a corrosion bloom can occur if the galvanising is damaged in some way and the surface is exposed to rain consistently over a period of time. Design should at minimum reflect the light framing code.
Hemp lime construction can be used with the full range of timber framing options including stud construction, post and beam, or double stud construction. Unless there are exceptional circumstances, simple stud construction is recommended as it minimises the amount of timber resource used.