Indicative detailing - The Hempcrete Topic: Designing and Building with Hemp-lime - page 577

In detailing a hempcrete building there are four main themes that the building designer
must understand, as discussed in the previous chapter. These are: the limits of the material,
in terms of its performance and structural integrity; the nature of the material, in terms of
its key characteristics; how it behaves during and after construction; and how it will behave
in the context of the particular site. The chance to visit a hempcrete building site during
the construction phase, including seeing some unfinished but set hempcrete, will give the
designer a real sense of the material and will provide a much more thorough understand-
ing of the issues than a topic could ever hope to convey. While this is not always possible
currently, it should be much easier as hempcrete builds become more commonplace.
Some essential questions to ask when detailing and designing for hempcrete are:
Does the design make sense within the structural limits of the material?
Can it be constructed easily?
Is the softwood structural frame safe from water ingress?
Can all the materials and fixings used withstand the alkaline environment?
Is vapour permeability maintained?
Is airtightness maintained?
Does the design reflect the demands of that particular building, on that specific site?
We recommend that, wherever possible, designers avoid complicating additions to the ba-
sic wall design, as the real beauty of hempcrete is in its simple, low-tech approach, with a
minimum of specialized technical solutions required. Even in the use of permanent shutter-
ing boards, for example, something intangible is lost. There is true elegance in the simpli-
city of the basic monolithic hempcrete wall with a central timber frame, and a lime render
and plaster finish.
Once the key issues are understood, the process of designing a hempcrete building should
be a relatively straightforward and rewarding one. The materials and methodology are low-
tech and the process of building is simple. Architects who are involved in designing sus-
tainable buildings and want these to be realized in a truly low-impact way, as well as those
who are influenced by the traditional vernacular and seek the beauty of a simple, natural
finish, will find much of value in hempcrete.