Restoration and retrofit - The Hempcrete Topic: Designing and Building with Hemp-lime - page 477

As it has a good amount of thermal mass, hempcrete complements the original solid walls
perfectly, working in the same way but adding insulation. In terms of thermal performance,
it is better to cast such insulation externally, as the thermal mass of the original wall is
wrapped inside the hempcrete insulation. This also minimizes disruption inside the prop-
erty, and doesn't subtract any of the living space inside the building. However, casting ex-
ternally is not suitable for all situations: buildings where the original façade is of historic
or aesthetic importance, for example, are usually best insulated internally. Also, casting ex-
ternally usually involves some small extension of the roof overhang, in order that it covers
the top of the hempcrete.
Hempcrete solid-wall insulation at a thickness of
70-100mm, with lime plaster applied.