Understanding Low Cost Housing | Civil Engineering Optional Notes for UPSC PDF Download

Low Cost Housing: Concept and Benefits

Building Cost Components

• Building Material Cost: 65 to 70%
• Labour Cost: 65 to 70%

In low cost housing, the building material cost is reduced by using locally available materials. Labour costs can also be minimized by efficient scheduling. Cost reduction is achieved through the selection of efficient materials or improved design.

Areas for Cost Reduction

1. Reduce Plinth Area:

   • Implementing thinner wall concepts, such as using 15 cm thick solid concrete block walls, can significantly reduce costs.

2. Use of Locally Available Materials:

   • Innovative use of local materials, such as soil cement blocks instead of burnt bricks, can lower expenses.

3. Energy Efficient Materials:

   • Materials that consume less energy, such as concrete blocks in place of burnt bricks, can be more cost-effective.

4. Environmentally Friendly Materials:

   • Substitutes for conventional building components, like using RCC door and window frames instead of wooden ones, can reduce both costs and environmental impact.

5. Preplan and Rationalize Design:

   • Careful preplanning of every component in a house and rationalizing the design process can help reduce the size and quantity of building components, thereby cutting costs.

6. Avoid Material Wastage:

   • By thoroughly planning each component, the wastage of materials due to the demolition of unplanned elements can be minimized, leading to significant cost savings.

7. Assess Necessity of Components:

   • Evaluate the necessity of each component in the house. If a component is deemed unnecessary, it should be excluded from the design, which can help avoid unnecessary costs.

By following these strategies, low cost housing can be both economical and sustainable, providing quality housing solutions without compromising on durability or performance.

Cost Reduction in Low Cost Housing through Ad Hoc Methods

1. Foundation Depth and Width:

   • For normal soil types (e.g., gravelly soil, red soil), adopt a foundation depth of 2 feet (0.6m) and width of 2 feet (0.6m) instead of the typical 3-4 feet depth. Use uncoursed rubble masonry with bond stones and good packing, thoroughly packed with cement mortar (1:8).

2. Arch Foundation:

   • For ordinary soil, use arch foundations to bridge loose soil pockets and reduce construction costs by up to 40%.

3. Under Ream Pile Foundation:

   • In black cotton and other soft soils, use under ream pile foundations, saving 20-25% in costs over conventional methods.

• Construct plinths 1 foot above ground level using a cement mortar (1:6). Replace the typical 4-6 inch plinth slab with bricks on edge to reduce costs by 35-50%. Ensure impervious blankets like concrete or stone slabs around the building to prevent soil erosion and foundation exposure.

1. Wall Thickness:

   • Use 6-9 inch thick walls for external construction and 4.5 inch thick walls for internal walls.

2. Rat-Trap Bond Wall:

   • Adopt rat-trap bond wall construction for thermal comfort and reduced material use, decreasing brick costs by 25% and masonry costs by 10-15%.

3. Concrete Block Walling:

   • Use concrete blocks (hollow or solid) instead of burnt bricks, reducing wall thickness from 20cm to 15cm, saving 10-25% in overall costs.

4. Soil Cement Block Technology:

   • Use soil cement blocks (soil mixed with 5%+ cement) in place of burnt bricks, avoiding plastering and achieving 15-20% cost savings.

• Replace wooden frames with concrete or steel section frames to save 30-40% in costs. Use block boards, fibre boards, or practical boards for shutters to reduce costs by 25%. Brick jelly work and precast components can improve ventilation and cut window component costs by up to 50%.

• Replace traditional RCC lintels with brick arches for small spans, saving 30-40% in construction costs and creating aesthetically pleasing exteriors.

1. Rational Design:

   • Replace traditional 5-inch RCC slabs with filler slabs and precast elements, reducing roofing costs by 20-25%.

2. Filler Slabs:

   • Use filler materials like bricks, tiles, or cellular concrete blocks in the bottom half of RCC slabs to replace non-functional tension concrete, creating aesthetically pleasing, structurally sound, and economical ceilings.

3. Jack Arch Roof/Floor:

   • Construct jack arch roofs/floors using compressed earth blocks as an alternative to bricks, saving on cement and steel, suitable for hot climates.

4. Ferrocement Channel/Shell Units:

   • Use ferrocement channel/shell units for floors/roofs, reducing costs by 30-40% over RCC slabs. These precast units facilitate speedy, economical construction and quality control.

• The cost of finishing items like sanitary fittings, electrical work, and painting depends on the quality and type of products used. Cost reduction in these areas is based on individual preferences and budget constraints.

Conclusion

These cost reduction strategies vary based on the building type, budget, geographical location, and material availability. Effective planning and design, supervised by experienced engineers or architects, can achieve overall cost savings of up to 25%.