EARTH, STRAW AND TRADITIONAL MATERIALS

Architects Anna Heringer and Eike Roswag from Linz and Berlin designed and built a school which was the recipient of The Architectural Review Awards for Emerging Architecture 2007.

Refining the local technique of using wet loam to build walls, the school has a brick foundation, a damp proof course, and walls made of a mixture of loam and straw. The straw acts as a form of reinforcement within the structure of the mixed material. The loam and straw are combined by getting cows and water buffalo to tread them in. The 'Wellerbau' ('wave-build') technique employed here involves building a 700mm high wall layer, leaving it to dry for two days, and then trimming off with a spade. A further drying period is followed by the addition of the next layer.

See www.meti-school.de/daten/schulbau.htm

See www.eartharchitecture.org

Straw House, Islington, London N1

We are featuring this house as it was a talk by Sarah Wigglesworth that started Ecotist and Ivy Ngeow Architects on the path to green building.

Architects Jeremy Till and Sarah Wigglesworth bought a plot of land next to a busy railway line in Islington, north London, at an auction.

It was a brownfield site that previously contained industry. There were sitting tenants (on a lease) so the Architects had to wait four years before they could start work. The building is a live-work office for their practice.

The materials they chose were mainly eco and green. The walls of the bedroom were made of straw bales, tightly packed to reduce the amount of air in the straw and so the danger of combustion. The structure was made of steel, which is not a green material, but the structure had to be rigid to stand on springs to attenuate vibration from the nearby railway line.

The rear wall of the living area was also made of straw. The idea was to give the bales a transparent waterproof covering, but this was not practical so all but one wall were clad in tin.

The office block was raised off the ground and sits on 10-foot-high walls made of gabions (cages filled with stones). See our article on Gabions and Bankshores.

The wall facing the railway was clad with sandbags to reduce noise, and the rest of the office block covered in a fabric quilting. The whole steel structure sits on springs, to dampen vibrations from the railway. This is partially effective.

Earthbags or sandbags are a way of building that is simlar to adobe or straw. Bags can be filled with sand, soil or rocks, or any suitable material such as recycled card. This provides insulation. They are the same as the traditional military sandbag wall and are very strong and retain a lot of thermal energy.

Hessian cloth (burlap) bags have been used for this purpose but they will rot over time. Polypropylene bags have much better strength and durability, but need to be out of direct sunlight as the UV will break them down.

If the walls are to be permanent they should be rendered with a resistant material.