Gaia Architects

regulatory approvals for low impact innovation

Light Earth Construction, Scottish Borders

Client: Department of Trade &Industry (DTI)

Light Earth is the generic term given to a method of construction whereby straw, woodchip, hemp, or some other suitable 'fill' material is coated in clay slip and set within shuttering as simple infill for walls. Research by Gaia produced the first major work on Light Earth Construction in English.

The aim of Gaia's 18 month project was to further the development of light earth construction. It involved the construction of a small building extension and guiding and appraising its journey through the regulatory and planning framework.


Light earth is never used in a load bearing capacity but is set within a frame to which both the shuttering, and later services, joinery etc. are fixed. It is usually made in situ, but can equally be constructed from blocks/infill panels. The surfaces are normally rendered on both sides, with lime based or earth renders. Light earth is best used as a designed moisture transfusive construction when it is inherently protected against the risk of interstitial condensation. The vapour permeability and hygroscopicity of the construction provides moisture mass and moderation of internal humidity levels, with indoor air quality benefits, provided that finishes are also vapour permeable.


The technique is one of a number that Gaia describes generically as "low impact construction". The techniques are capable of delivering radical resource economy, through energy efficiency in use and low embodied energy of materials. Waste is avoided altogether. Most of the materials used in low impact construction are renewable, cheap, and benign but labour intensive, making them highly suitable for self-builders and a good medium for construction training.


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