Finishes for hempcrete - The Hempcrete Topic: Designing and Building with Hemp-lime - page 417

Figure 13. Plan views of window jamb. (a) A hardwood bead detail with burnt sand mastic provides
a natural alternative to stainless-steel or PVC frame-seal beads. (b) Here the bead has been de-
signed out by extending the hempcrete over the window frame.
When choosing a sealant, bear in mind that synthetic mastics have high embodied energy
and contain toxic chemicals. You may therefore wish to consider using a traditional burnt
sand or linseed oil mastic, both of which are made from natural materials and do not con-
tain toxic substances.
Just as effective as a stainless steel or PVC or glass-fibre bead is a hardwood bead detail.
Rather than being incorporated into the render, this is applied afterwards to cover the join
between render and frame, and held in place with burnt sand mastic or linseed oil mastic
sealant (see Figure 13(a) ). Alternatively, the bead detail can be designed out by adapting