The Pine Calyx project appears to be a great example of what I like to call backyard engineering (NCE 8 September). Local resources, tradition infused with innovation, sustainability and a hand crafted approach to fabrication and construction.
Presumably the technique could be developed to include geometries other than circular?
Without detracting from the achievement of this project, readers may also be interested in a more 'home baked' tradition of masonry vault building.
While teaching at the Architectural Association we visited a brick works near Stoke on Trent where circular 'beehive' kilns were used for firing. The roof of these kilns were domical and needed to be rebuilt periodically.
A local team of bricklayers had been constructing these domes, presumably for many years, in a similar way to the Guastavino vaults without formwork and using clay bricks rather than tiles. The 'mortar' was, from memory, a clay slurry to form the necessary bonding between the brick rings.
An ingenious trammel type arrangement was used to define the dome geometry - a timber pole at the plan centre, able to twist in plan with a hinged connection to a second timber.
The mason could therefore control the intrados geometry as this was being constructed. I believe the spans were around 6-8m in diameter with a rise to span ratio well below the very impressive 1: 8.6 at Pine Calyx.
David Tasker, Thorganby, York, Capita Symonds, David.Tasker@capita. co. uk