Construction of low cost housing by using the low cost building materials increases the access to buildings by low income group peoples. Low cost housing can be achieved by use of efficiet plannng and project management, low cost materials, economical construction technologies and use of alternate construction methods availabe. The profit gained from use of such methods can decrease the cost of construction and make the low cost housing accessible to all.
The use of low cost alternate building materials also prevents the rise of construction cost due to use of scarce building materials which eventually increase the cost of the project.
Selection of Materials for Low Cost Housing:
The first step to low cost housing material selection is to select ecofriendly building materials. This also enhanaces the sustainable design principle. The life cycle of a building os pre-building, building and post-building stages. Each stage of building should be such that they help conserve the energy. These three stages indicate flow of building materials through different stages of a building. Pre-building stage mainly consists of manufacture which is subdivided in processing, packing and transport. The building phase mainly consists of construction, operation and maintenance whilst as the last stage would be disposal where the material can be recycled or reused.
1) In Manufacturing of low cost building materials – Pollution prevention:
Manufacturing of building materials should be environment friendly. Efforts should be made to study and revise the technologies for producing good quality, efficient building materials and should improve the waste generation during manufacturing. These results in reduction of pollutants to environment.
2) Recycling of wastes in Manufacturing – The wastes which can be recycled can and used in masonries whilst as wooden wastes can be used in manufacture of plywood or soft boards. (Courtesy-BMTPC)
3) Reducing Energy Consumption and use of Natural materials – The total energy required to produce a material is called embodied energy. The greater a materials embodied energy; it requires a greater usage of non-renewable sources. It is therefore advantageous to use materials or composite materials prepared from the wastages. The natural materials such as stones, wood, lime, sand and bamboo can be used in ample where ever possible. The natural materials impact more sustainability to structures as well as they are friendlier to environment.
4) Use of Local material – The use of local materials reduces the dependence on transportation whose contribution to the building material cost is high for long distance. Use of locally available building materials not only reduces the construction cost but also are suitable for the local environmental conditions.
5) Energy Efficiency – Energy efficiently of a building material can be measured through various factors as its R value, shading coefficient, luminous efficiency or fuel efficiency. Energy efficient materials must reduce the amount of generated energy.
6)Use of non-toxic building materials: Use of toxic building materials can significantly impact the health of construction people and the occupants of the building. Thus it is advisable to use the non-toxic building materials for construction. There are several chemicals including formaldehydes, benzene, ammonia, resins, chemicals in insulations, ply boards which are present in furnishings and building material. The effect on health of these toxic materials must be considered while their selection and they should be used only where-ever required.
Higher air cycling is recommended while installation of materials having volatile organic compound such as several adhesives, paints, sealants, cleaners and so on.
7) Longitivity, durability and maintenance of building material: The use of durable cosntruction materials does not only enhance the life of the building but also reduces the cost of maintenance. The lower maintenance costs naturally save a lot of building operating cost. The materials used in building determine the long term costs of an operating.
8) Recyclability and reusability of building material: A material should be available in form which can be recyclable or reusable. Ex – the plastics waste can be used for recycling and producing newer materials. The scrap from steel can be used to manufacture the rcc bars, binding covers and other miscellaneous steel products in building construction.
9) Biodegrability –A material should be able to decompose naturally when
discarded. Natural materials or organic materials would decompose very easily. It is also a very important consideration whether a material decomposes naturally or produces some toxic gases.
Composites as Building Materials:
The composite building materials are made of composition of two or more materila which have enhanced property. Natural fiber materials are coming up as excellent substitutes for the prevailing building materials. Fibers likes jute, sisal coconut, ramie, banana are cheap and environmentally suited as they are made from natural fibers. They are also replacing the fiber reinforced plastics.
Composite building materials present immense opportunities to replace traditional materials as timber, steel, aluminum and concrete in buildings. They help in reduction of corrosion and their low weight has been proved useful in many low stress applications. Each type of composite has its own characteristic properties and thus useful for specific purpose.
Jute fiber reinforced polypropylene composites, coir fiber reinforced composites, sisal fiber and wollastonite jute pultruded composites are a few to be named. CBRI has developed MDF composite doors containing coir fiber, cashew nut, shell liquid (CNSL) as natural resin and Para formaldehyde as major constituents.
Many composite building materials are generated from glass fibres and industrial wastes. These materials are used for manufacturing of portable toiles, water storage tanks, outdoor furniture, bath tubs, interior decoration, basin, door, window frames etc. Thus the application of composite building materials in construction vary from cladding to internal furnishings and the owner highly benefits due to their application because of their light weight, resistance to corrosion and availability in different colours. Pultrusion is most cost effective method for producing composite profiles. It is commercially applicable for light weight corrosion free structures, electrical non conductive systems and so many other functions.
The pultruded items are recognized and recommended in the Global markets. Pultrated sections are well established alternative to steel, wood and aluminium in developed countries and catching fast in other parts of the world.