The area to be completed with cob flooring was backfilled up to -1ft from the expected finish level and was lined with earth-crete plinth wall.
The cob floor should be protected from termites. So as a precaution we started the flooring with a layer of Charcoal followed by a layer of Quarry Dust. As the particles of Quarry dust are sharp, they get interlocked with each other and form a compact base and charcoal is a natural termite repeller.
The earth base on which the flooring is done acts triggers capillary effect when the ground gets very wet during rains. And because of the capillary effect the water rises up and comes out of the earthen floor and ends up creating damage to the floor. Thus a layer of Pond liner sheet was laid as water proofing layer for the flooring.The pond liner can get torn because of sharp quarry sand particles. Thus to provide a soft bed alayer of sand was laid on the Quarry dust layer before laying the pond liner.
Then up to a level just 1” below the expected finish level earth (free of organic matter) was filled and compacted by rammiing in layers of 3 to 4”. (It is easy to compact the earth fill if it is made slightly moist)
The clay water is poured on the rammed earth layer so that the final layer of cob mix can bind well with the rammed earth fill. Mix consisted of Fine Earth + Fine sand + Straws mixed with clay as a binder in the ratio 4:2.5:1.5. This mix is laid in 2 layers that add up to a thickness of 1”. The first layer may have some cracks. The second layer is laid to cover up all the cracks and to make smooth and flat surface.
5 coats of linseed oil is applied for water proofing,termite proofing,to make it more durable and to create a rich sheen. Before laying each coat it should be made sure that the previous coat is thoroughly dry. Care should be taken that excess of linseed oil is not let to accumulate on the small undulations that can be present (This will create uneven drying and the linseed oil peels of in plastic like layers). Linseed oil can be mixed with a little amount of turpentine to quicken the drying of the coats.
Then a final layer of bee-wax polish is applied.This makes the floor shiny and givesbetter waterproofing.