Eco Architecture Made Easy: How Light Straw Clay Might Be the Next Great Thing
It is an unusually hot morning for early May, and we are clustered on the western side of the half-complete, skeletal structure of Heartland’s new school building and community center. At our feet is a fluffy heap of barley straw, to our right is a halved, recycled water tank, awash in a deliciously smooth clay and water concoction: slip.
In a day and age of vast overuse of energy-intensive building materials, the only logical place to turn, when it comes to the recreation of the Garden Route’s infrastructure, is towards sustainable building techniques. When I say recreation, I mean the mass rebuild which had to take place after the 2017 fires ravaged a 300km stretch of South Africa’s pristine south coast.
With the intention to both minimise negative ecological impacts and maximise the use of locally produced renewable materials, eco architecture aims to incorporate sustainable design practices which involve the integration of the building into its natural environment.
Heartland School of Self-Sufficiency was burned to the ground when the fires swept through the back-to-back farms and smallholdings just outside Sedgefield. In their case, when it comes to working closely to their environment, they’ve made use of clay harvested from a small deposit on the banks of their dam, locally sourced barley straw, and a generous assortment of materials both donated or salvaged from the wreckage left from the fire.
With the intention to both minimise negative ecological impacts and maximise the use of locally produced renewable materials, eco architecture aims to incorporate sustainable design practices which involve the integration of the building into its natural environment.
Heartland School of Self-Sufficiency was burned to the ground when the fires swept through the back-to-back farms and smallholdings just outside Sedgefield. In their case, when it comes to working closely to their environment, they’ve made use of clay harvested from a small deposit on the banks of their dam, locally sourced barley straw, and a generous assortment of materials both donated or salvaged from the wreckage left from the fire.
All bricks used for the foundation were sourced from previous buildings on the land which burnt, while the turf roof, which is now planted generously with sour fig, actually survived the fire. This new building will not only be the new school space but also a community center, comprising of a pottery studio, music room, and yoga space utilised as an engaging, co-creative learning environment.
The partly-finished building is a delightfully creamed-honey colour and is veined in the texture of the straw. Fine green shoots are beginning to sprout from the older walls as they dry out beneath the autumn sun. This is natural and important to the process. As the remaining barley and wheat seeds in the straw sprout, the tiny roots assist in further binding the wall, and their dying-off is a natural indication of moisture levels in the wall, marking an apt time to begin the final process of plastering.
The design of the building primarily incorporates a timber framework and light straw clay infill. The process of the infill is swift and simple, once all core aspects are in place.
A fine slip is made by roughly sieving the clay and combining it with a 2:1 ratio of water to the clay. The clay mixture can then be sieved again through a fine mesh to eliminate any large clumps. The final consistency should be that of thick cream – it looks good enough to eat, and certainly good enough to bathe in.
A fine slip is made by roughly sieving the clay and combining it with a 2:1 ratio of water to the clay. The clay mixture can then be sieved again through a fine mesh to eliminate any large clumps. The final consistency should be that of thick cream – it looks good enough to eat, and certainly good enough to bathe in.
This slip is then combined with the straw (barley or wheat, whichever can be locally sourced) until lightly coated. The quantities equate to roughly four liters of slip for enough straw to stuff into a 25-litre bucket. The final product should only be wet enough to clump when squeezed and is then put aside to cure overnight.
Then to build the walls.
The tamping process is equally straightforward. Wooden formwork is applied to either side of the timbre framework and light straw mixture is applied in layers or ‘lifts’ – approximately 20cm when loosely packed – before it is stamped firmly down, either by foot or with a wooden tool.
Then to build the walls.
The tamping process is equally straightforward. Wooden formwork is applied to either side of the timbre framework and light straw mixture is applied in layers or ‘lifts’ – approximately 20cm when loosely packed – before it is stamped firmly down, either by foot or with a wooden tool.
Depending on the width of the panel and the height of the wall, this is a process with varying degrees of difficulty. I brace myself alongside a crossbeam and work my feet up and down the narrow space, as the damp straw compresses delightfully beneath my toes. By the time we’ve worked the wall halfway up, however, I am half wedged against the roofing, awkwardly suspended by one arm tucked around a broad beam. It’s almost time to abandon footwork entirely.
Any gaps or spaces found within the infill once the panel is complete can be plugged with ‘chinking’ – a denser mixture of river sand, clay, and straw that can be stuffed into or smoothed over the areas. Give it a couple of weeks to dry out and sprout, then plaster of lime and cow dung smooths things over for your light straw clay home. Voila!
Any gaps or spaces found within the infill once the panel is complete can be plugged with ‘chinking’ – a denser mixture of river sand, clay, and straw that can be stuffed into or smoothed over the areas. Give it a couple of weeks to dry out and sprout, then plaster of lime and cow dung smooths things over for your light straw clay home. Voila!
This is a process that finds all the elements in motion. Earth and water in their physical form; as well as air and the sun’s heat, are intrinsic to the drying and crystallization of the wall’s final structure.
Although it is one of the lesser-known methods of sustainable building – which sits in the shadow of the more common cob or adobe techniques – Light Straw Clay is likely one of the most cost-effective, simple, and yet highly durable techniques when it comes to building naturally.
More information on the building technique can be found in Essential Light Straw Clay Construction, available on Amazon.
Heartland School of Self-Sufficiency is now up and running once again, and you can see more about them on their Facebook Page. By Skye Mallac
Although it is one of the lesser-known methods of sustainable building – which sits in the shadow of the more common cob or adobe techniques – Light Straw Clay is likely one of the most cost-effective, simple, and yet highly durable techniques when it comes to building naturally.
More information on the building technique can be found in Essential Light Straw Clay Construction, available on Amazon.
Heartland School of Self-Sufficiency is now up and running once again, and you can see more about them on their Facebook Page. By Skye Mallac
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