Eco-clay walls

Clay Technology magazine
1 Jun 2007

Natural Building Technologies’ (NBT) ThermoPlan wall system has received an ‘A’ rating in the Building Research Establishment’s (BRE’s) Green Guide to Housing Specification.

ThermoPlan is a 365mm deep wall cavity system. Its porous clay structure makes it thermally efficient while minimising cold bridging and damp/cold cavities. The blocks are airtight, fireproof and fully breathable, which prevents water vapour from becoming trapped in the building and eliminates the risk of internal or intersitial condensation.

The system is a thin bed construction solution, so the clay blocks only require one-millimetre bed joints and use dry interlocking vertical joints, thus reducing drying out time. ‘It has proven quite popular in the UK, due to the simple thin bed process and speed of construction,’ explains NBT’s Sales and Marketing Director Neil Rodger. ‘Build times are up to three times faster than in conventional cavity walling.’

The structure, created in Germany 20 years ago and acquired by NBT in 2002, is produced from a mixture of clay and sawdust that is formed into blocks and heated in an oven. The high temperature burns away the sawdust, leaving small air pockets within the blocks that provide strong thermal efficiency (see image above).

‘Normal cavity walls are made from cement or aggregate, and require a great deal of energy to create,’ explains Rodger. ‘The clay blocks are simply extruded and fired, as you would a brick, which means it is less energy intensive.’ The company says its blocks have 30% less embodied CO2 than comparable systems.

ThermoPlan is suitable for low rise buildings that are up to four storeys high, and the external wall blocks have a force capacity of six kilonewtons. The system has been used in several commercial, housing and schooling projects, including the Seashells Children and Family Centre in Sheerness, UK.

The updated Green Guide to Housing Specification from BRE provides guidance on the environmental impact of common requirements in housing. The very low Ecopoints scored byThermoPlan shows that it has a minimal impact on the environment. It has therefore been awarded one of the highest ratings within the guide’s ‘external cavity wall construction’ category.

‘Installing ecologically sound systems is at the heart of what we do, so it is very important to have our credentials verified,’ says Rodger. ‘The BRE are key assessors, so we couldn’t ask for a better accreditation.’


Further information:

Building Research Establishment
Natural Building Technologies