Since ‘rammed earth’ is cheap, tough and green, why aren’t more people using it to build with?

With the increasing trend for ‘Green’ technology and construction techniques to reduce C02 emissions, the use of ‘bricks’ made from rammed earth could become much more common.

What is rammed earth, and how is it used in construction?

As the name suggests, the primary material used in rammed earth construction is the earth itself. Rammed earth has a history in the UK and is seen as a traditional form of walling construction.

However, it has been used more extensively in recent years by environmentally aware architects exploring natural alternatives.

Walls are generally built on well-drained strip footings or a slab foundation with a generous masonry plinth and damp course to protect the earth walls from moisture.

Without the addition of a stabiliser such as cement, rammed earth is better suited to internal partitions or in conjunction with other structural materials.

What are the potential issues?

The use of rammed earth bricks on new build sites raises a number of considerations;

  • Durability – there is a risk of the bricks decaying in the presence of water
  • Strength – The ability to produce a consistent strength of ‘brick’ in a non-factory environment and potential inconsistency of ‘soil’ materials used.
  • Maintenance – Requires a high degree of on-going maintenance to keep wall panels free from water penetration.
  • Flooding – Unsuitable for sites at risk of flooding.
  • Protection – Additional protection is required by the use of large roof overhangs to reduce the wetting of the panels at eaves and verges.
  • ResistanceWalls need to be at least 300mm or more in thickness to ensure sufficient lateral resistance.
  • MaterialSelecting appropriate material is critical. Only subsoil’s should be used and need to be carefully graded. Materials should also be from known quarry sources to improve consistency and reliability.
  • VariabilityThe potential variety of subsoils used means sampling is required to undertake testing to prove consistency.

For more information check out the LABC Warranty Technical Manual

By Olivia Catterall