quarry fines from a local quarry. Mixing the material is also a challenge, making sure the clay is thoroughly crushed and integrated. Building the forms and the tamping of the material in the forms is also a relatively unforgiving process. There are a number of forming systems available but most are best carried out by experienced builders. Rammed earth walls defy alteration, and require special provision for mechanical conduits, etc. Going beyond one story is certainly possible, but, with the current state of technology, increasingly expensive as the building goes higher. Rammed earth installation also requires lots of wood for forms, and obviously this is only an ecological proposition if the forms can be constantly reused. In cold climates, like most of Canada, rammed earths great mass is also not enough to make it energy-efficient; it requires more insulation (typically external rigid insulation board, covered with stucco). Because rammed earth is not the ideal do-it-yourself building method, it tends to be trapped between economic models. On one hand, like other natural building forms, rammed earth is an unfamiliar building mode to most contractors and officials. Most builders cannot so easily get into it because the technology specifically developed for it is minimal, and the building process is still way more time-intensive than mainstream building. On the other hand, unlike other forms of natural building, do-it-yourselfers can not simply decide to compensate for this lack of professional support with their own sweat equitythat is, without a lot of additional trouble. One hopeful development in making rammed earth more attractive to the average contractor is a new technique developed by long-time RE builder David Easton. Called P.I.S.E. (for Pneumatically Impacted Stabilized Earth), the technique was inspired by