Visually this building technique issimilar to extruded earth tubes.The earth hasto beas free of clay as possible, mostly pure sand which has no binding properties.The 'binder' is jute sacks which are 2.6 m long and about 0.5 wide.The sand-filled sacks are piled up as walls within a light timber framework.The sand can also be mixed with hydraulic lime mortar or cement, and the sacks dipped in water before being piled up, so the mix becomes hard enough to make the slightly temporary binding power of the sacks superfluous. It is also possible to add some lightweight aggregate to increasethe insulation value.
Weather protection of exposed earth structures is important. The outside and inside walls can be rendered with hydraulic lime or lime cement plaster. The inside can also be rendered with lime or clay plasters, (see Chapter 15). Walls exposed to extreme weather should be protected by timber panelling fixed to battens nailed directly onto the earth wall. The nails usually fasten to the earth wall without any problem. Internal walls can also be covered with panelling or wallpaper, or painted with mineral or casein paints. The surface of the walls must not be treated with a vapour-proof paint, as this would quickly lead to moisture gathering inside the wall, thus allowing frost damage.
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