Indicative detailing - The Hempcrete Topic: Designing and Building with Hemp-lime - page 531

detailing some of the more technical parts of the hempcrete building, and, where ap-
propriate, present some functioning solutions.
An important concept central to many detailing decisions when designing any building is
airtightness. Hempcrete buildings are no exception, and we therefore discuss the concept
of airtightness first in this chapter, and return to it throughout as we look in more depth at
detailing specific parts of the building.
Note: all the details described or shown in this topic are for indicative purposes only. They
should be considered as inspiration for your own specific building design, the actual de-
tailing of which should be undertaken by a suitably experienced or qualified designer, ar-
chitect or engineer. The overall design of any building, including individual details there-
of, remains the responsibility of the building designer. A building's design should be con-
sidered for appropriateness within its own site and climate. If your architect or engineer is
in any doubt about this, then seek specific advice from someone who is used to working
with hempcrete.
Airtightness
Airtightness has become the buzzword of the moment in the field of sustainable building,
as those people who want future-proof homes rush to seal themselves into plastic boxes in
the name of reducing energy consumption.
Airtightness is a key concept, and a certain level of airtightness is needed in order to stop
heat transferring out of the building via draughts in leaky buildings. The 'airtight line' is a
conceptual line drawn around the thermal envelope (see Figure 21 ) , along which all junc-
tions of different building elements are detailed to ensure that air cannot escape between
them. Where the building elements along this line are not in themselves airtight, they can
be improved with an airtight membrane. In effect, the conceptual airtight line ensures that
the building's designer has to consider the airtight envelope. Unfortunately, however, this
widely used concept of the airtight line around the thermal envelope is often taken rather
too literally.