Earth Plaster System
Earth plaster is a natural clay-based wall finishing system composed of clay, sand, and fibre (typically straw or animal hair), applied as a render or interior plaster to masonry, timber-frame, straw-bale, and earthen substrates. Earth plasters are among the oldest building finishes in human history, used continuously for millennia across every inhabited continent. Unlike cement renders, clay plasters remain hygroscopic and vapour-permeable after application, actively regulating indoor humidity by absorbing and releasing moisture. They cure by drying rather than chemical reaction, meaning they can be reworked, repaired, or recycled simply by re-wetting. Modern commercially prepared clay plasters are available pre-mixed with consistent aggregate grading and natural pigments, offering architects a low-carbon, non-toxic interior and exterior finishing option that meets contemporary performance expectations while maintaining traditional material qualities.
- Interior wall finishing
- Natural building render
- Heritage conservation
- Health-conscious interiors
- Humidity-regulating finish
Earth plaster is arguably the oldest surface finish in architecture, with evidence of clay renders on wattle-and-daub structures dating back over 6000 years in Mesopotamia and the Indus Valley. In Africa, decorative earth plasters have been used for millennia with techniques passed through generations. Traditional Japanese tsuchikabe (earth wall) construction developed sophisticated multi-coat clay plaster systems over centuries. In Europe, clay plasters were standard interior finishes through the medieval period before being displaced by lime and later gypsum plasters during industrialisation. The 20th century natural building revival, beginning in the 1970s, brought renewed interest in earth plasters. In Australia, the publication of HB 195-2002 (The Australian Earth Building Handbook) provided formal guidance. Today, commercial clay plaster products from companies like Clayworks (UK), American Clay, Tierrafino (Netherlands), and Claywise (Australia) have made earth plasters accessible to mainstream construction, with consistent quality, colour ranges, and documented performance data.
DISCLAIMER: This specification document is generated from the CLAD Materials Atlas Database. Information is for general guidance only and does not constitute professional engineering advice. Values are typical and may vary by batch, manufacturer, and production run. Verify suitability for specific project applications independently.