Placing hempcrete - The Hempcrete Topic: Designing and Building with Hemp-lime - page 360

Placing around horizontal frame sections
Where horizontal timbers form part of the frame, extra care needs to be taken to ensure
complete and even placement of the hempcrete at a consistent density around and espe-
cially under these frame members. Because it is so hard to reach into the shuttering and
shove the last bits of hempcrete under a horizontal timber, the tendency is for small sec-
tions to get missed, or for the hempcrete in these areas to be either too loose or over-com-
pacted.
For this reason, wherever possible, horizontal timbers should be kept out of the frame
design, but in certain circumstances, including the frame around windows, timbers for
electricity sockets to fix to, and the extra horizontal battens used in an exposed frame
design, it is unavoidable.
With an exposed frame design, horizontal battens as 'rails' are fixed to the upright studs
at 600mm centres going up the frame. To make things easier, some hempcrete contractors
recommend fixing these rails as the build progresses. Since the standard shuttering lift is
also 600mm, the shuttering can be filled to the top, and a rail laid along the even flat top
of the filled shuttering and fixed, then a new shuttering board is fixed and more hemp-
crete placed on top of and either side of the batten. This is a great idea, as it allows the
easy placement of even density hempcrete all around the batten, and the horizontal batten
doesn't get in the way as you are tipping the hempcrete into the shuttered void. However,
on a large, busy build this may not be compatible with the way that the hempcrete casting
has to fit in around other works. Whole-building runs of shuttering before another lift is
started are not always possible in practice, and on a busy site the job of fixing the rail be-
fore the next lift of shuttering goes up sometimes gets forgotten. Since these rails provide
such a vital function, you might decide it is safer to fix them all to the frame at the outset,
before placing any of the hempcrete.
Reviewing the success of hempcrete placing
It is essential to review the success of your team's hempcrete placing, so that mistakes can
be picked up early and adjustments made to the placing technique. This needs to be done
after building a test panel, at the end of the first day's placing, and then again as necessary
throughout the build.