Calyx, Pines Gardens
The rammed chalk Calyx is a visitor centre, conference centre, exhibition space, classroom and low energy build demonstration. It is set in the beautiful Pines Gardens, an organically run public garden facing the sea at the White Cliffs of Dover.
Surveyors Conker Conservation oversaw the design process and took the role of clients representative. They are specialists in solar and Passivhaus design work. We were asked to build double storey earth retaining walls for this earth sheltered building using the chalk dug from the site, some 650 tonnes. The chalk on site was not particularly strong, crushing at .8Nmm2. The engineer had not designed for this material before and the walls were expected to take both compression and lateral loads. With that in mind the walls were designed to be 650mm thick, which at that time were the thickest walls I had ever been asked to build.
After the soil was carefully extracted and we had separated the topsoil from the chalk, work could begin. There was only one straight wall in the whole design. Most of the building was set on a 12m diametre, but in the middle of the ground floor there was a series of more normal 300mm walls built on a series of compound curves.
Once the ground floor walls were built the first floor slab was poured, giving us time to build a 3m diametre boiler house on which the beautiful “bovedas tabicadas” dome was tested.
Once that was completed work continued on the first floor walls, with the slab propped from below to allow our Bobcat to drive on the green slab.
Rammed chalk was chosen for a number of reasons: the way it looks, the enormous carbon emmision saving made from not having to remove the soil from site, removing the need to bring manufactured materials to site, the price and getting the benefit of the enormous thermal mass the walls allow.
The walls were curved on the inside faces but facetted on the outside to allow standard 2.4m x 1.2m insulation batts to be fixed directly to the walls, with a waterproof membrane in between. The walls took 8 weeks to complete including the boilerhouse.
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©2007 Rowland Keable