Growing urbanisation has led to migration towards cities and resulted in an increased demand for affordable low-cost housing. Moreover, with sustainability gaining momentum, there is a need to balance both energy consumption and the environmental impact of materials used for building houses. Low-cost building materials not only increase access to permanent housing for people from low and middle-income groups but also contributes towards sustainability, particularly when locally available building material is used.
The materials commonly used for modern low-cost construction are hollow concrete blocks, bamboo, extruded clay bricks, compressed earth bricks, concrete panels, along with non-conventional materials like polymers and recycled composite blocks, as they can reduce construction time by half. In this ideabook, we look at some of the types of building materials suitable for low-cost housing in India.
One of the first building materials known to man along with stone and wood, bamboo is used even today in rural areas of countries in Asia, Africa and Latin America for building homes. It is a green building material, which is very popular in India due to its low cost, low weight and durability but should be treated with appropriate chemicals to make it termite resistant. As India produces nearly half of the world’s bamboo, homes in earthquake-prone areas of the country are built with bamboo. The material has better tensile strength than steel and is also fire resistant. More recently, corrugated sheets of bamboo have been developed, and these are used for roofing as experts consider it to be an ideal substitute for asbestos and galvanised sheets.
Concrete blocks are fabricated at factories according to specifications of home builders. Made by mixing Portland cement, water, stone or quartz these blocks can either be solid or hollow and are generally lightweight, durable and fire-resistant. These are used for the foundation, basement walls and partition walls as their cores can be filled with steel rods for enhancing strength. As they are made of cement, they are termite resistant, soundproof and provide natural insulation against heat and cold.
These are increasingly being used for meeting requirements of permanent housing as the cost of regular brick and mortar homes continues to rise exponentially. These houses are made of components that are factory manufactured and then assembled at the house site. The components include steel frames, wooden panels, cement and gypsum for floors along with factory fabricated doors, windows, ceilings and walls. Depending on the requirements, the components like wall and ceiling panels, as well as structural steel frames, can be custom made and then assembled. Though these materials are nearly 15 per cent more expensive than traditional materials, their high level of efficiency and low labour costs bring down the overall construction expenses. They remove the need for auxiliary activities like wiring, plumbing and plastering, which are carried out at the casting stage.
These bricks are developed out of mud and reinforced with a mixture of lime and cement. Also known as adobe bricks, they are lightweight, non-toxic and fire-resistant. Compressed earth bricks are dense and generally used for exterior stucco work and are considered one of the cheapest among low-cost building materials.
These bricks are designed with a projection on one side and a depression on the other so that they align with bricks of a similar type, like a jigsaw puzzle, to make walls. Interlocking bricks are made out of laterite stone powder, cement and gravel. They are considered green building materials when compared to baked bricks as they dry naturally and are just as sturdy.
This sustainable building material is commonly used in rural areas to make weatherproof homes as they provide both strength and durability. Natural fibres like coconut and straw increase the strength and durability of pure mud while a coating of sulphur improves the water-resistance of the walls. Other types of fibre bricks are made with cereal straw, bagasse, corn straw and rice husk, which are combined with cement to make them corrosion resistant and strong.
Also called as ‘eco cement’, this material is made out of several waste materials but has high durability and requires only 20-40 per cent of the energy needed for the production of Portland cement. It does not cause any harm to residents of homes where it is applied as a sustainable building material.
These bricks are used for constructing load-bearing walls of low rise buildings and are made of fly ash, stone powder or sand, slag and cement or gypsum for bonding. Some categories of fly ash bricks are also made out of mineral residue, glass, water, and fly ash and are energy efficient, water-resistant and provide natural thermal insulation for a low-cost house.
Homes made out of steel shipping containers are fast becoming popular among people exploring recyclable building materials. While the smallest one can make a 100 sq ft house, one would need around 8-9 large containers to set up a 1500 sq ft home with two floors. It is as cost-effective as a prefabricated home as the container only needs to be arranged on a prepared foundation.
Composed of gypsum, lime, quartz sand, water and aluminium powder, these blocks are developed under heat and pressure within an autoclave according to specific requirements. The blocks can be used for both exterior and interior walls and are known to be heat resistant and lightweight. The material reduces energy costs as it is porous and non-toxic. It is environment-friendly too as it generates 30 per cent less solid waste in comparison to traditional concrete.
Here are some ideas for low-cost houses that are easy to construct.