I studied 16th-century original barns, says Julian Pirie, and that led me to decide to build a five-bay, L-shaped “barn” with a square corner room. The whole would be 260 square metres in area in total. I decided to put posts at 3.8 metre centres, with a cradle of beams catching the rafters at their mid-point. The three-metre high doors would face the courtyard and all would be enclosed by 2.4 metre-high, rammed-earth walls around the remaining perimeter.
Rammed earth is a barely moist mix of cement and, in this case, milled sandstone. This mixture is built up into the wall by being compressed between formers in situ. A section of two metres or so goes up 50 mm at a time, to reach a height of 2.4 metres high by 300 mm thick by mid-afternoon. The mixing is important, so I modified a Morrison multi-hoe to run in a trough, with special blades.

Read more in the Aug/Sept 2010 issue of The Shed