“A 450 mm deep trench suffices for non load bearing walls. This depth is adequate for bamboo column foundations. A level base for earth bags can be prepared by simply tamping the trench base. If heavy loads are imposed on the earth bag wall, a simple concrete base should suffice. Generally, the fill material should be 30 per cent clay and 70 per cent sand. Stabilisers such as cement can be added to the mix to endure better bonding of all constituents. Bags should be filled to 80 per cent of their capacity,” explains Phadke adding that they used discarded cement sacks from nearby construction sites.

The earth bags were then stitched with a flat plastic thread and laid along the trench, leaving space for the bamboo footings. They were then tamped with a home made tamping rod till compacted properly. On completing a course, two strands of barbed wire about six inches apart were placed on top and the procedure repeated. Door opening and windows were spanned with conventional lintels or earth bag arches with bamboo supports. The earth bag courses were corbelled to create a conical roof or a dome shaped structure. Finally, chicken mesh was stretched over the earth bag wall to provide the rough base for the plaster to hold on.

While externally, regular plaster was applied for surface finish and to ensure the durability of the structure, internally, the team tried out different natural mixes—wheat flour, cowdung, paneer, whey, paper-mache etc for the walls and the floor. Old hoardings were used on the roof for waterproofing.

... contd.