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Rammed earth – Lightwave discovers the essence of WA

Working across cultures and regions requires Lightwave designers to carefully and sensitively uncover and understand the essence of a place. Indeed, I argue that being an outsider allows opportunities to discover the unique attributes of a place and rearticulate them into the built environment in ways not previously considered. Our current work in Western Australia has brought us into contact with rammed earth and I recently toured Margaret River to truly understand where the material originated from, how it is made, and to assess its performance characteristics.

Rammed earth makes rustic yet elegant walls

The use of rammed earth walls in region is the holy Grail when it comes to an architect’s search for the expression of truth in materials and structure. Predominantly made from a limestone sand mix, an abundant material in the region, the rammed earth walls provide a solid thermal mass wall highly appropriate for the regions climate (that is cold winter months and hot summer days with cool nights). The rammed earth walls in this region have been developed by a number of local tradesmen who have worked in a craftsman like manner to refine and develop the technology so it can meet the demands and rigors of modern construction requirements.

A formwork shutter system similar to insitu concrete is used as forms for the rammed earth walls

The rammed earth walls are made from a limestone gravel mix, with a 12-20mm aggregate depending on the required performance and finish. An admixture is included into the mix to provide additional waterproofing and also prevents any long term deterioration. This mix is placed into a formwork not dissimilar to a concrete shutter system in a series of 600mm increments. A pneumatic compactor compresses the earth and the process repeats itself until the desired height is reached.

The tie bolts that hold the form together also provide the textural circles that form a part of the material's finish

Varying the quantity of lime in the mix will alter the colour… colour hues can be modified to appear as rusty orange tones through to more pinky tones. The limestone nature of the rammed earth walls makes the product very similar to concrete (concrete is after all lime and aggregate) with the warm texture of a natural material. The walls can be structural or decorative, and single storey walls are 300mm wide, with two storey walls requiring a width of 400-450mm wide. Costs of the rammed earth wall start at $350m2 and require no painting, rendering or additional internal finish.

Colour hues can be modified by varying the amount of lime in the mix

All in all an incredibly delightful material that is sustainable, durable and practical and adds significantly to the quality of a space in which they are used.

Acknowledgement to Peter McCartney from South West Rammed Earth, Margaret River who will be the subcontractor on our aged care project in Mandurah.


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