Shuttering - The Hempcrete Topic: Designing and Building with Hemp-lime - page 308

Shuttering around openings in the wall
To create openings in the wall for windows and doors, shuttering boards need to be fixed
around the inside of the framework defining the opening. Since the frame timbers either
side of the opening, and for the lintel, are double timbers, this makes a secure support for
the boards, which are screwed straight through into the face of the timbers. However, un-
less the frame is a double frame (exposed on both sides), the corners of the boards inside
the opening, on both sides in the case of a central frame, will be at risk of moving about
when the hempcrete is being placed. This can be solved by blocks of timber placed up
into the corners where these boards meet each other (as in shuttering corners Method 2,
see page 178 ) , or sections of batten running across the whole width of the board inside the
opening (i.e. spanning the width of the wall), with screws going right through the timber
(from inside the doorway or window) to fix into the boards.
Straight reveals can easily be constructed with the shuttering in this way, while straight-
sided angled reveals are probably also best formed by casting, using more complex shut-
tering. To achieve delicate rounded reveals where the wall curves gently into the reveal in
a continuous surface, cast them square or angled, and then shape them by hand with a nail
float as the hempcrete is hardening (see Chapter 18, page 244 ).
The shuttering method described above for creating openings for doors and windows can
be through the wall. These might include, for example, alcoves, shelves or cupboards that
are inset into the finished wall and are partly or completely formed by the casting of the
hempcrete itself, in whatever form pleases you. Obviously there is a limit to the depth to
which the alcove can extend without significantly reducing the insulation provided by, and
the strength of, the hempcrete that remains.