Planning the build - The Hempcrete Topic: Designing and Building with Hemp-lime - page 188

Clearly, it can be difficult to find a balance between being able to rely on the necessary
number of people turning up and having lots of extras wandering around that you don't
know what to do with. In our experience, it can be worthwhile (especially when volunteers
are looking at the experience as a training exercise) charging a nominal fee in advance, say
£10 per day to include all tea and coffee, lunch and provision of PPE: this can make the
difference between people turning up or not.
See also Chapter 5, page 73 , for more on using volunteer labour.
Drying times
Since hempcrete is a wet-mixed material, which takes several weeks to dry out sufficiently
for finishes to be applied, and because this time can vary depending on local weather con-
ditions during and immediately after the construction phase, obviously this can affect the
build in ways that need considering at the planning stage.
A common complaint, especially on commercial builds, is that the hempcrete is taking too
long to dry out and that the delay in applying finishes means that extra costs are being
incurred (usually because external scaffolding cannot be taken down until the render has
been applied).
This is a problem that can be anticipated and designed out, for example by the use of a
cladding finish with a vented air gap, which can be applied much sooner than a render fin-
ish, or by arranging the schedule of works to accommodate this drying stage.
If drying time is properly planned for in the schedule of works it should not be an issue,
and if necessary, after a few weeks finishes can be applied to the external face of the wall
and the scaffolding removed while the wall continues to dry to the inside. This needs con-
sidering at the design stage, since it would not be possible in certain situations, for example
if internal permanent shuttering board was used.
Good 'drying management' once the hempcrete is cast can speed the process considerably,
and, again, with proper planning this can be incorporated into the schedule of works from
an early stage so that everyone on-site understands what their responsibilities are in this
regard. For more information on drying of hempcrete, see Chapters 15 , 16 and 19 .