Natural Materials

Back in the 1960s and 70s everyone wore nylon shirts. They had lots of advantages to do with convenience and looking modern. But it wasn’t too long before people realised they were extremely uncomfortable because they didn’t let your body breathe in the way that natural cotton or wool does. Buildings are the same.

Since the mid 19th Century Portland Cement has become a major component of building worldwide. All emphasis is now on making buildings impervious to moisture. Now, however, we realise this approach can  be a liability. The cement industry is one of the main industrial sources of NOx and CO2 emissions. Cement is strong, but also brittle. When it cracks, water can seep in, but can’t get out – a bit like sweat under a nylon shirt.  Many current damp problems and their associated health issues are caused by non-breathing construction materials.

Lime and Clay Plasters are Different.  Clay plasters work to protect the wall not by shedding water off the surface, but first, by absorbing it. The material then swells, which means the molecules press closer to each other, closing the gaps. As the air outside the wall dries up, the plaster naturally and invisibly releases its own extra moisture. This natural phenomenon means the walls are constantly able to breathe. Moisture and humidity are naturally regulated. Even if a disaster happens such as a burst water main, a straw wall can dry out because of the breathability of the plaster.

Building Breathable Walls is not only more eco-friendly.  It also contributes to the noticeable difference in feel that a straw bale building for the humans inside.  Some of this peaceful difference is to do with the more absorbent acoustic properties of the walls. Some of it is to do the natural regulation of humidity as opposed to the very dry atmosphere you sometimes get with buildings depending on heating and air-con systems.

Not all the materials used in our building will be naturally occurring. For example, if we can build on car tyre foundations then we will, because of the positive aspects of using something that would otherwise end up in a landfill for thousands of years. But generally speaking, natural materials and natural processes are preferred.

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