B A S I C M AT E R I A L S F O R E A R T H B A G B U I L D I N G 2 7
lengths, with the twelve-inch (30 cm) variety being better suited for earthbag walls. These ties are shaped with a loop at both ends and are installed by folding the wire in half and wrapping the bent center around the barbed wire so that the two looped ends will protrude out beyond the wall. Commercial wire-ties (as they are referred to in the catalogues) are twisted tight with a manual or automatic wire-twisting tool. The manual one looks like a big crochet hook that is inserted through the two end loops and turned by hand. The automatic twisting tool has a spring-return action that twists the loops together with a pulling action rather than a twist of the wrist, and so is less tiring. Both tools are reasonably priced. Tie wires are also used to secure electrical conduit and plumbing lines along interior walls (refer to Chapter 7). Tie wires are also used to anchor strawbales with exterior bamboo pinning cinched tight with extra long tie wires. (Look for illustrated details of this method in Chapter 17). During construction we install long enough lengths of tie wire to project beyond the wall at least
two inches (5 cm). Secure the tie wires to the barbed wire every 12-24 inches (30-60 cm) every other row to provide an attachment source for the chicken wire later on. In addition, this provides an alternative fastening system for chicken wire other than nails. Most suitable rammed earth will hold a two-inch (5cm) or longer galvanized roofing nail for attaching stucco mesh after the walls have had sufficient time to cure. For added security and to avoid the potential of fracturing the earth, we may consider using the tie wires as an alternative attachment source. A single row of tie wires may be installed as a means of attaching a “weep screed hose” to create a “capillary break” between the plaster and the top of a stem wall (see Chapter 4 for more on this).
Arch Window and Door Forms Although we use a flexible form for our walls we use a rigid form to make the empty spaces for our windows and doorways (Fig. 2.22). This is the only place that requires a temporary support system during construction (domed roofs are self-supporting). The box forms
2.22: Rigid form supporting door and window placement.