The hempcrete wall: an overview - The Hempcrete Topic: Designing and Building with Hemp-lime - page 207

There are several ways of using hempcrete within the structure of a building, but its
'standard' use, which is probably the most familiar to those who have seen or
worked with the material, is the construction of solid (monolithic) walls to form the
thermal envelope.
This chapter describes the principles of construction and the typical construction method
for a cast-in-situ hempcrete wall. There are other ways of using the material in walling,
depending on the specific application and the specifications of the architect or building de-
signer, but the basic principles are the same.
Later chapters in this part of the topic provide an expanded discussion of the methods used
and skills involved at each stage of wall construction. Other than the information given
in this chapter on services, all topics relating to the wall build-up are covered more thor-
oughly in the rest of Part Two. The purpose of this chapter is to give a broad overview of
the entire walling system.
Hempcrete wall construction principles
A hempcrete wall is built with natural materials and provides a very high level of thermal
and acoustic insulation and is 'breathable', so provides moisture buffering - passive regu-
lation of humidity, which is beneficial both for human health, because it improves indoor
air quality, and for the fabric of the building. Different levels of insulation can be achieved
by casting different thicknesses of hempcrete, but a standard thickness in new build would
typically be 300mm or 350mm. The thermal performance achieved varies according to the
exact materials used.
As a monolithic cast-in-situ walling system, hempcrete effectively minimizes the chance
of thermal bridging, by forming a continuous sheet of insulation material all around the
building. The wall build-up, in its simplest form, uses only two or three different materials
(lime, hemp, timber), which adhere closely to one another, and it contains no cavity, thus
minimizing the risk of interstitial condensation.
More information about the benefits of using natural insulation materials and the thermal,
moisture management and other properties of hempcrete can be found in Chapters 4 and 7 .
Hempcrete walls are cast around a structural timber frame, as they are not strong enough
to be load-bearing. Although they have some strength in compression, this is not enough