The likes of stone, timber and clay may have a low environmental impact, but are they a good choice in the modern world?
Natural sources can provide almost every component required to build a house. Wood can be turned into boards and beams, including highly engineered glulam (glued laminated timber) plus, cladding, flooring and roofing. Straw bales, rammed earth and cob – a mixture of clay, straw and sometimes lime – have all been used for self-builds.
Timber processed into fibres is made into insulation. The same as hemp, wool and recycled fibres from newspaper, cellulose, jute sacks and even denim. For interior finishes there are raw clay and mineral-based plasters, and mineral paints.
Often natural materials have an innate beauty, and are characteristic of the local area. An example is the limestone found in the Cotswolds and the Scottish larch used in weatherboarding or shingles. They also have a more appealing appearance than synthetic finishes – which may be an advantage when seeking permission to build. But natural materials don’t have to create the country cottage look. They can be used to create a rustic finish or a crisp, contemporary design.
Health and wellbeing
These products tend to have low toxicity. One example is natural fibre insulation, which is usually treated with low-toxicity mineral salts to reduce flammability. Whereas synthetic foams may contain organophosphate flame retardants, which can have an adverse effect on health. Natural finishes and insulation are a rational choice for creating a healthy home – and they are nice to handle, too.
As long as they are responsibly sourced and processed, most natural materials have relatively low environmental impact. They do not require the amounts of energy used to create brick, concrete and steel. Instead coming from readily renewable sources.
Processing any material inevitably involves some energy use. But you can see exactly how much as responsible manufacturers record the details in Environmental Product Declarations (EPDS). Materials such as timber and stone can be reused – possibly several times. By contrast, synthetic materials are much harder to reuse. One day you may need to dismantle or replace part or even all of your home – so it will help if it can be taken apart and be reused.
Structure and insulation
The most straightforward and economical natural option for housebuilding is timber. Carpentry skills are widespread, and beautiful homes have been built more or less entirely from timber and wood products, from the structure to the insulation, cladding, even interior finishes.
‘Using certified timber from sustainably managed forests is an obvious choice of material for modular and bespoke homes,’ says Oliver Rehm, the CEO of Baufritz UK. ‘Compared to cement and steel it has many advantages – it is local, renewable, recyclable, lightweight and easy to manufacture as well as being an excellent thermal insulator.’
Your home could also be built from materials such as hemp composites, earth and straw. Other than when it’s used for thatch, straw isn’t a traditional construction material. However, this is starting to change because it is an abundant byproduct, relatively cheap and easy to handle, and the hollow stems offer good insulation. Straw and hemp are also used in prefabricated panels for a more conventional approach.
If you want to get really hands on with your self-build, you can learn how to work with straw bales on a practical course such as those offered at the School of Natural Building. Natural insulation tends to be heavier, and to perform properly it may need to be thicker than synthetic versions. This is not necessarily a disadvantage – its weight reduces temperature variations and creates a quieter building.