Rammed Earth

Rammed Earth

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Rammed earth is an ancient technology for building load bearing walls. Earth technologies differ from mud in having less water in the building mix and relying on different forms of compaction to achieve cohesion and density. Because they have less water once compacted earth walls tend to have higher density than mud walls, and therefore higher strength.

In the case of rammed earth material is chosen as suitable, this may be ‘as dug’ on site, or a blend of as dug and imported material, or totally imported.

Testing is carried out, either field testing or by labs, depending on the value and complexity of the work.

Once chosen the material must be well mixed and the correct moisture content achieved, this may be with a simple but effective drop test, or by more involved weighing tests. Once mixed and brought to the correct (optimum) moisture content (OMC), it is placed in loose layers inside a formwork or shuttering. This can be extremely simple wooden sides with a rope tourniquet, or the most up to date system formwork with steel frames and ply facing.

Material is then rammed into a form or shutter either manually or mechanically, the resulting density is the same. Rammed earth can achieve very high levels of compaction because three conditions can be altered. The first is the depth of the layer to be rammed, the second is the size of the rammer head and the third is the force or weight of the rammer.

Once rammed successive layers are put into the form and work continues. In this way structures can be built ‘traditionally’ by building a series of horizontal sections before going higher, or it may be built vertically, achieving heights of around seven metres in one operation.

Due to its very simplicity rammed earth is able to be used in very small projects with little money, or by large commercial contractors. It has been used to good effect in developing country situations and by large UK contractors with no previous experience.

Rammed earth is an ancient technology for building load bearing walls. Earth technologies differ from mud in having less water in the building mix and relying on different forms of compaction to achieve cohesion and density. Because they have less water once compacted earth walls tend to have higher density than mud walls, and therefore higher strength. In the case of rammed earth material is chosen as suitable, this may be ‘as dug’ on site, or a blend of as dug and imported material, or totally imported.

Testing is carried out, either field testing or by labs, depending on the value and complexity of the work. Once chosen the material must be well mixed and the correct moisture content achieved, this may be with a simple but effective drop test, or by more involved weighing tests. Once mixed and brought to the correct (optimum) moisture content (OMC), it is placed in loose layers inside a formwork or shuttering. This can be extremely simple wooden sides with a rope tourniquet, or the most up to date system formwork with steel frames and ply facing.

Material is then rammed into a form or shutter either manually or mechanically, the resulting density is the same. Rammed earth can achieve very high levels of compaction because three conditions can be altered. The first is the depth of the layer to be rammed, the second is the size of the rammer head and the third is the force or weight of the rammer. Once rammed successive layers are put into the form and work continues. In this way structures can be built ‘traditionally’ by building a series of horizontal sections before going higher, or it may be built vertically, achieving heights of around seven metres in one operation.

Due to its very simplicity rammed earth is able to be used in very small projects with little money, or by large commercial contractors. It has been used to good effect in developing country situations and by large UK contractors with no previous experience.

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7 thoughts on “Rammed Earth

  1. Is there any guidance available in the UK, about the ability of earthbag construction to meet building regulations for a residential building?

    1. Hi Reuben,

      I don’t believe there is any guidance available specifically about meeting the building regs. But there certainly is information about Earthbag building, and I would consult an architect about getting a building through the building regs.

      Paul (EBUK chair)

  2. Thank you for your reply L-) Are you able to recommend any architects that specialise in this sort of building… I seem to be really struggling to find anybody that can help!

    1. Could you let me know whereabouts you are based, and the size of the project?

  3. We are near Peterborough and it would be a relatively small project. We would ideally like to build a 10m roundhouse with reciprocal living roof.

    1. You should come to our conference in Norwich on the 14th Feb! I would contact Cob builder Kate Edwards or Colin Williams architects at WCK design

  4. If I can get the time off work I will hopefully be there! Thank you for your help 🙂

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