The future is mud

By Stacy Wrenn

Exterior of the Riedmuller house.

The technological advance of steel-frame construction by the Chicago School in the late nineteenth century is arguably the single most revolutionary move in recent architectural history. It enabled building on a mass scale, in number and in height. The concept of the ‘vertical city’ was born. Smog filled the streets of cities and industrial waste polluted the rivers. This heightened focus on ‘upscaling’ urban centres led to a degradation in living conditions and contributed significantly to the dangers of climate change we are currently faced with through the harmful toxins it released into the atmosphere.

We are in desperate need of another revolution, one that is both sustainable and accessible. In the past decade we have seen the creation of scientifically advanced materials with a lesser carbon footprint in the manufacturing process than traditional building materials, but because of their price, they are only available to the few and not the many. There is a small but growing international movement that believes they have found the perfect solution, a carbon-neutral home that can be built for less than a thousand euro. The future is mud.

We are in desperate need of another revolution, one that is both sustainable and accessible.

More specifically, the future is cob. Cob is an ancient material that is a mixture of clay, sand, straw, and water. It is found with some variations across the world under different names – adobe in Central America, swish in Ghana. Cob was the main material of residential building in Ireland for centuries due to its low cost and ease of manipulation, but after the Great Famine (1845-1852) its reputation was stained and the wider public did its best to forget its existence. The habitation of the daoine beo bocht that we know mainly from prints, bodies in ditches with grass stains around their mouths. Tales of the ‘famine cottages’ with damp walls and collapsing thatch roofs were particularly potent in the mid-twentieth century when the Irish government undertook mass housing projects such as the Ballymun Flats – as if to justify what would be revealed to be poor-quality builds by having the public believe things were worse before.

While there are some disadvantages to building with cob, such as the limited time you have during the year where the weather conditions are appropriate (basically, it cannot be raining), the benefits far outweigh them.

Firstly, the economic argument for cob is that because it is such an easy material to work with – once you provide the physical effort – you can cut back on the amount of labour needed, and outside contractors are not necessary. The man credited with reinvigorating cob architecture in the West Country of the United Kingdom, Kevin McCabe, has built most of his creations with the help of volunteers who are passionate about the medium or want to learn through firsthand experience so they can build their own homes in the future. The clay soil necessary for a sound structure can be found in the subsoil dug up at most building sites when they are in the process of laying foundations, and most cob builders make arrangements with contractors to essentially dump the soil on their property – usually free of charge. Deals are also made with local farmers for the straw.

While there are some disadvantages to building with cob, such as the limited time you have during the year where the weather conditions are appropriate (basically, it cannot be raining), the benefits far outweigh them.

On an environmental level cob building is non-toxic and the materials are completely recyclable. If one builds walls that are one to two feet thick there is little need for heating even during winter months as it’s a natural insulator that retains the heat. McCabe admits to adding sheets of polystyrene on the exterior of his projects but he puts this down simply to the new restrictions on planning permissions in the United Kingdom – this is not required under Irish planning laws.

Lastly, in terms of aesthetics, the constraints of building as we know it are eliminated with curvature and abstraction possible with great ease. Cob lends itself to more organic forms, with one house by McCabe having a floor plan inspired by the geometry of a snail shell. You can also freely carve and sculpt designs into the walls as you please, as the image below outlines. This is the most pleasurable part of the process of building with cob, for even though it does not require someone to have twenty years of experience with it before ‘mastering’ it does need to be carried out meticulously in order to avoid any unnecessary issues down the line.

Riedmuller's cob house inside-2

Interior of the Riedmuller’s house.

The balance between the clay, sand, and straw needs to be found, with the straw being added in after the soils have been mixed together with water. The straw needs to be threaded into the mix and the most thorough way of doing this is by foot with repetitive stomps until there are no visible strands simply resting – the straw is what holds the material together and stabilises it for construction. This is a slow process even with volunteers helping, but if you wanted to you could substitute feet for an operational digger and a large pit. In doing so, however, you lose part of what makes this such a great material to work with – the satisfaction of being able to look at the finished product and say ‘I made that possible’.

The cob is then separated into rounded bricks that are stacked on top of the stone foundation where they are merged and smoothed down – but the surface has to be dampened when adding more or else the structure will crack and potentially crumble when dry. A lime render is added once the construction is complete to protect the clay from being washed out by the rain – a necessity in the Irish coastal climate in particular. However, the cob is porous so this is not a major issue, but most European builders add in wide roof eaves for extra protection from weathering.

A testament to the strength of cob can be found at The Hollies Centre in Enniskeane, Co. Cork where a community founded on sustainable living has continued to grow since 1999.  Their houses vary from straw builds to by-the-book cob, with hemp fibre floors and windows made from the bottoms of recycled glass bottles. A full tour of their community is available as part of their regular workshops and open days, including the ‘studio cottage’ built by the Riedmuller’s son when he was only 16 with an eco-roof with wildflowers hanging from the sides, blending in with its surroundings. This building perfectly encapsulates why cob is the way forward for architecture – it’s accessible, it’s clean, and it works with the environment rather than leaving a concrete path of destruction in its wake.


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