Details of stepped foundation

The natural surface of ground may not always remain smooth & by and large to an extreme that there exist a significant slope either across or along or both across and along the site of most buildings.

Where the ground floor should be located at or just over the ground level at the maximum point, it becomes essential to arrange some dry fill material like broken brick or concrete hardcore to uplift the level of the over site concrete and floor. As soon as it is formed, this fill will be set, extended and compacted up to the external wall.

To spend less in excavation and foundation walling on sloping sites where the subsoil, like gravel and sand, is consolidated it is essential to develop a stepped foundation, which variances diagrammatically the cutback in excavation, and foundation walling of a level and a stepped foundation.

A footing in which the preferred width is ensured with a series of steps regarding the proportion of one unit of horizontal dimension to two units of vertical dimension.

A foundation built up in a series of steps that estimate the slope of the bearing stratum.

The objective is to get rid of horizontal force vectors that might produce sliding.

On sloping sites, exact decision should be taken regarding whether the ground floor should be located over ground at the highest point or partially submerged underneath ground.

The foundation is stepped up the slope to reduce excavation and walling underneath ground. The foundation is stepped to keen the height of each step below the thickness of the concrete foundation and the foundation at the higher level goes beyond the lower foundation by minimum 300 mm.

The load bearing walls are elevated and the foundation gutters around the walls back-filled with selected soil from the excavation. The concrete over site and solid ground floor is casted on granular fill within 600 mm deep or cast or placed as a suspended reinforced concrete slab. The drains provided at the back of the trench fill are placed to gather and drain water to the sides of the building.

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