LOW COST HOUSING

LOW COST HOUSING

ACKNOWLEDGEMENT

Before proceeding with the details of the seminar i thank almighty allah for making my seminar report a successful one.I am deeply thankful to my seminar advisor PROF. AMARANTH SHETTI and co-ordinator PROF. MALLIKARJUNA HIREMATH who gave valuable information and support to complete this seminar work with ease. Also my grateful thanks to PROF. PHALACHANDRA H .M head of department and our honourable principal DR .H UDAYA PRASANNA who gave support in all aspect.I also express my gratitude towards the faculty members of civil engineering department for their timely help and advice provided towards the preparation of this seminar report.This acknowledgement will be incomplete without admitting the cooperation from my beloved parents, friends, batch mates and well wishers without whose help I w would not have complete this task.I thank one and all...............

Mawan Rasheed8sem Civil Engineering

ABSTRACTS:

Adequate shelter for all people is one of the pressing challenges faced by the developing countries. India is currently facing a shortage of about 17.6 million houses. The dream of owning a house particularly for low-income and middle-income families is becoming a difficult reality. Hence, it has become a necessity to adopt cost effective, innovative and environment-friendly housing technologies for the construction of houses and buildings for enabling the common people to construct houses at affordable cost. This paper compares construction cost for the traditional and low cost housing technologies. Case studies in India are used for the investigation. Construction methods of foundation, walling, roofing and lintel are compared. Strength and durability of the structure, stability, safety and mental satisfaction are factors that assume top priority during cost reduction. It is found that about 26.11% and 22.68% of the construction cost can be saved by using low cost housing technologies in comparison with the traditional construction methods in the case studies for walling and roofing respectively. This proves that using low cost housing technologies is a cost effective construction approach for the industry.

CONTENTS:

1.1: Introduction41.2: low cost housing51.3: General methods51.4: cost effective techniques91.4.1: foundation91.4.2: plinth111.4.3 Walls121.4.4 Roofs and floor141.4.5 Openings161.5: cost effective analysis221.6: case study241.7: conclusion271.8: References28

Figures:

Figure 1.1: Building by recycled materials7Figure 1.2: precast RC planks9Figure 1.3: prefabricated brick panels9Figure1.4: precast hollow slab10Figure 1.5: arch foundation11Figure 1.6: under rimmed piles12Figure 1.7: plinth12Figure 1.8: rat trap bond brick13Figure 1.9: rat trap bond bricks14Figure 2.0: brick jail15Figure 2.1: precast RC planks17Figure 2.2: Ferro cement roofing channels18Figure 2.3: Ferro cement C beams19Figure 2.4: Filler slab technique21Figure 2.5: Arch opening22Figure 2.6: Case study24

TABLES

Table 1: cost analysis of low cost housing on footing work22Table 2: cost analysis of low cost housing on roofing work 23

Chapter 11.1 INTRODUCTION

Low cost housing can be considered affordable for low- and moderate-income earners if household can acquire a housing unit (owned or rented) for an amount up to 30 percent of its household income (Miles, 2000). In developing countries such as India, only 20% of the population are high-income earners, who are able to afford normal housing units. The low-income groups in developing countries are generally unable to access the housing market. Cost effective housing is a relative concept and has more to do with budgeting and seeks to reduce construction cost through better management, appropriate use of local materials, skills and technology but without sacrificing the performance and structure life (Tiwari et al., 1999). It should be noted that low cost housings are not houses which constructed by cheap building materials of substandard quality. A low cost house is designed and constructed as any other house with regard to foundation, structure and strength. The reduction in cost is achieved through effective utilization of locally available building materials and techniques that are durable, economical, accepted by users and not requiring costly maintenance (Miles, 2000). High efficiency of workers, minimize waste in design and apply good management practices, can also be achieved. Low cost housing is a new concept which deals with effective budgeting and following of techniques which help reducing construction cost through the use of locally available materials along with improved skills and technologies without sacrificing the strength, performance and life of the structure (Kumar, 1999; Civil Engineering Portal, 2008). Low cost housing technologies aim to cut down construction cost by using alternatives to the conventional methods and inputs. It is about the usage of local and indigenous building materials, local skills, energy saver and environment-friendly options.

1.2 LOW COST HOUSINGAdequate shelter for all people is one of the pressing challenges faced by the developing countries. India is currently facing a shortage of about 17.6 million houses. The dream of owning a house particularly for low-income and middle-income families is becoming a difficult reality. Hence, it has become a necessity to adopt cost effective, innovative and environment-friendly housing technologies for the construction of houses and buildings for enabling the common people to construct houses at affordable cost. This paper compares construction cost for the traditional and low cost housing technologies. Case studies in India are used for the investigation. Construction methods of foundation, walling, roofing and lintel are compared. Strength and durability of the structure, stability, safety and mental satisfaction are factors that assume top priority during cost reduction. It is found that about 26.11% and 22.68% of the construction cost can be saved by using low cost housing technologies in comparison with the traditional construction methods in the case studies for Walling and roofing respectively. This proves that using low cost housing technologies is a cost effective construction approach for the industry.

1.3 METHODS ADOPTATION:1.3.1 RECYCLING1.3.2 EXTENSIVE OR LOGICAL PLANNING1.3.3 MODULAR APPROACH1.3.4 PREFABRICATION1.3.5 MATERIALS ADOPTATION 1.3.1: RECYCLING:Recycled materials adopted for low cost housing includes Wood from demolished houses Rubbers previously used Recycled glass and metals. Use of disposal containers.Recycled materials used are inexpensive and usage of waste materials of building construction decreases the waste load from a city. Various houses constructed using disposal containers and packages are strong to bear the load.

Fig 1.1

1.3.2: EXTENSIVE OR LOGICAL APPROACH:In extensive and logical approach optimum usage of materials are preferred. Various considerations for technical and economical analysis are There should be a optimal space in the design considering efficiency of space , minimum circulation space. Economy should be considered in design of individual buildings , layout , clusters etc While preparing the specification it should be kept in mind the cost effective construction system. Energy efficiency has gained considerable importance due enegy crisis especially in developing countries. To develop an effective mechanism for providing appropriate technology based shelter for economically weaker section of people

1.3.3: PREFABRICATION:In prefabrication, housing constructions are done by prefabricated materialsIt includes:

In prefabricated construction, as the components are readymade, self supporting, shuttering and scaffolding is eliminated with a saving in shuttering cost. In conventional methods, the shuttering gets damaged due to its repetitive use because of frequent cutting, nailing etc. On the other hand, the mould for the precast components can be used for large number of repetitions thereby reducing the cost of the mould per unit In prefabricated construction, the work at site is reduced to minimum, thereby, enhancing the quality of work, reliability and cleanliness The execution is much faster than the conventional methods, thereby, reducing the time period of construction which can be beneficial in early returns of the investment. In prefabricated housing system, time is saved by the use of precast elements which are casted off-site during the course of foundations being laid. The finishes and services can be done below the slab immediately. While in the conventional in-situ RCC slabs, due to props and shuttering, the work cannot be done, till they are removed. Thus, saving of time attributes to saving of money.

1.3.4: MATERIALS USED ARE:

1.3.4.1: Precast RC planks:This system consists of precast RC planks supported over partially precast joist. RC planks are made with thickness partly varying between 3 cm and 6 cm. There are haunches in the plank which are tapered. When the plank is put in between the joists, the space above 3 cm thickness is filled with in-situ concrete to get tee-beam effect of the joists. A 3 cm wide tapered concrete filling is also provided for strengthening the haunch portion during handling and erection. The planks have 3 numbers 6 mm dia MS main reinforcement and 6 mm dia @ 20 cm centre to centre cross bars.

Fig 1.21.3.4.2: Prefabricated brick panels:Brick panel is made of first class bricks reinforced with two MS bars of 6 mm dia and joints filled with either 1:3 cement sand mortar or M-15 concrete. Panels can be made in any size but generally width is 53 cm and the length between 90 cm to120 cm, depending upon the requirement. The gap between the two panels is about 2 cms and can be increased to 5 cms depending upon the need. A panel of 90 cm length requires 16 bricks and a panel of 120 cm requires 19 bricks (Figure 4). (P.K.Adlakha and H.C.Puri, 2002)

Fig 1.31.3.4.3: Precast RB curve panels.1.3.4.4: Precast hollow slabs.Precast hollow slabs are panels in which voids are created by earthen kulars. without decreasing the stiffness or strength. These hollow slabs are lighter than solid slabs and thus save the cost of concrete, steel and the cost of walling and foundations too due to less weight. The width of a panel is 300 mm and depth may vary from 100 mm to 150 mm as per the span, the length of the panel being adjusted to suit the span. The outer sides are corrugated to provide transfer of shear between adjacent units. Thekulars are placed inverted so as to create a hollow during precasting (Figure 9). Extra reinforcement is provided at top also to take care of handling stresses during lifting and placement. There is saving of about 30% in cost of concrete and an overall saving of about 23%.(P.K.Adlakha and H.C.Puri, 2002)

Fig1.4

1.3.5: MATERIALS ADAPTATIONS: The various materials which can be used for low cost housings are Non eroded mud plaster Fly ash sand lime bricks. Solid concrete and stone blocks. Bamboo mat boards. Stabilised compressed earth. Fly ash gypsum stabilized mud blocks Clay red mud burned bricks Precast stone blocks.

1.4: COST EFFECTIVE VARIOUS TECHNOLOGIES ARE:1.4.1: FOUNDATION: Foundation is the lowest part of structure which is provided to distribute load to the soil thus providing base for the superstructure. in the conventional process the excavation work is first carried out , then the earth work is filled with the available earth and end with watering and compaction in 6 thick layer .1.4.1.1: Arch foundation: But for low cost housing arch foundation is used in which walls are supported on the brick or stone masonry. For the construction of the foundation, the use of available materials such as brick or concrete bloc can be made to resist the lateral forces buttress at the corner. it reduces 40% of cost . Advantage of this is that it can e used in soft soil.

Fig 1.5

1.4.1.2: Rubble Masonry: random rubble masonry in mud /cement mortar placed in excavation over thick sandy bed.Normally the foundation cost comes to about 10 to 15% of the total building. It is recommended to adopt a foundation depth of 2 ft (0.6m) for normal soil like gravel soil and red soil etc. it is suggested to adopt arch foundation in ordinary soil.In case of black cotton soil and other soft soil, it is recommend to use ream pile foundation , ream pile foundation have mechanically formed enlarge bases that have been as much as 6m in diameter. The form is that of an inverted cone and can only be formed in stable soils. the large base diameter allows greater bearing capacity than a straight shaft pile. These piles are suited for expansive soils which are often subjected to seasonal moisture variation.

Fig1.6

1.4.2: Plinth:It is suggested to adopt 1 ft. height above ground level for the plinth and may be constructed with a cement mortar of 1:6. The plinth slab of 4 to 6 which is normally adopted can be avoided and in its place brick on edge can be used for reducing the cost. By adopting this procedure the cost of plinth foundation can be reduced by about 35 to 50%.It is necessary to take precaution of providing impervious blanket like concrete slabs or stone slabs all round the building for enabling to reduce erosion of soil and thereby avoiding exposure of foundation surface and crack formation.

Fig 1.71.4.3: Walls: Wall thickness of 6 to 9 is recommended for adoption in the construction of walls all-round the building and 41/2 for inside walls. It is suggested to use burnt bricks which are immersed in water for 24 hours and then shall be used for the walls1.4.3.1: Rat-trap bond brick It is a cavity wall construction with added advantage of thermal comfort and reduction in the quantity of bricks required for masonry work. By adopting this method of bonding of brick masonry compared to traditional English or Flemish bond masonry, it is possible to reduce in the material cost of bricks by 25% and about 10to 15% in the masonry cost. By adopting rat-trap bond method one can create aesthetically pleasing wall surface and plastering can be avoided.Fig 1.8

Fig 1.91.4.3.2: Concrete blocks walling:

In view of high energy consumption by burnt brick it is suggested to use concrete block (block hollow and solid) which consumes about only 1/3 of the energy of the burnt bricks in its production. By using concrete block masonry the wall thickness can be reduced from 20 cms to 15 Cms. Concrete block masonry saves mortar consumption, speedy construction of wall resulting in higher output of labour, plastering can be avoided thereby an overall saving of 10 to 25% can be achieved.

1.4.3.3: Soil cements block technology:

It is an alternative method of construction of walls using soil cement blocks in place of burnt bricks masonry. It is an energy efficient method of construction where soil mixed with 5% and above cement and pressed in hand operated machine and cured well and then used in the masonry. This masonry doesnt require plastering on both sides of the wall. The overall economy that could be achieved with the soil cement technology is about 15 to 20% compared to conventional method of construction.

1.4.3.4: fly Ash Sand Lime Bricks:By mixing of lime and fly ash in the presence of moisture, fly ash sand lime bricks are made. Fly ash reacts with lime at ordinary temperature and forms a compound possessing cementations properties. After reaction between lime and fly ash, calcium silicate hydrates are produce which are responsible for high strength of the compound. Bricks made by mixing lime and fly ash are therefore, chemically bounded bricks.the bricks are manufactured with the help of hydraulic press and are dried in the autoclave. These bricks have various advantages over clay bricks , it possess adequate crushing strength uniform shape, smooth finish , and does not required plastering and also are lighter in weight than ordinary clay bricks (R.K.garg 2007)

1.4.3.5: BRICK JALI: The common burnt brick is one of mans great inventions. Five thousand years ago bricks were made in many different shapes and sizes but, one by one, the less satisfactory ones were discarded. Now, all over the world, with only a few exceptions, nearly all bricks are roughly the same shape and size - that is about 9 x 4.5 x 3 inches. This is neither accidental nor coincidence but the result of five thousand years of what we now call R & D - research and development. Brick jail can be used instead of parapet wall or boundary walls , it will reduce the bricks and intern reduces the cost.Instead of using the regural lintel and window system , jail work can be used

Fig 2.0

1.4.4: ROOFS AND FLOORS:Structural floors and roofs accounts for substantial cost of the buildings in normal situation. Therefore , nay savings achieved in floor and roof considerable reduces the cost of construction . traditional cast insitu concrete roof involve the use of temporary shuttering which adds to the cost of construction and time. Use of standardized and optimized roofing components where shuttering is avoided prove to be economical, fast and better in quality.Some of the prefabricated roofing/flooring components found suitable in many low cost housing projects are: Precast RC planks. Prefabricated brick panels. Precast RB curve panels. Precast RC curve channel roofing. Precast hollow slab. Precast concrete panels. L panel roofing. Trapezon panels roofing. Un reinforced pyramidal brick roof.

1.4.4.1: Precast RC Plank Roofing System:This system consists of precast RC planks supported over partially precast joist. RC planks are made with thickness partly varying between 3 cm and 6 cm. There are haunches in the plank which are tapered. When the plank is put in between the joists, the space above 3 cm thickness is filled with in-situ concrete to get tee-beam effect of the joists. A 3 cm wide tapered concrete filling is also provided for strengthening the haunch portion during handling and erection. The planks have 3 numbers 6 mm dia MS main reinforcement and 6 mm dia @ 20 cm centre to centre cross bars.

Fig 2.1

1.4.4.2: Precast Curved Brick Arch Panel Roofing: This roofing is same as RB panel roofing except that the panels do not have any reinforcement. A panel while casting is given a rise in the centre and thus an arching action is created. An overall economy of 30% has been achieved in single storeyed building and 20% in two or three storeyed buildings (Figure 7). (P.K.Adlakha and H.C.Puri,2002)

1.4.4.3: Precast hollow slabs roofingPrecast hollow slabs are panels in which voids are created by earthen kulars. without decreasing the stiffness or strength. These hollow slabs are lighter than solid slabs and thus save the cost of concrete, steel and the cost of walling and foundations too due to less weight. The width of a panel is 300 mm and depth may vary from 100 mm to 150 mm as per the span, the length of the panel being adjusted to suit the span. The outer sides are corrugated to provide transfer of shear between adjacent units. Thekulars are placed inverted so as to create a hollow during precasting (Figure 9). Extra reinforcement is provided at top also to take care of handling stresses during lifting and placement. There is saving of about 30% in cost of concrete and an overall saving of about 23%.(P.K.Adlakha and H.C.Puri, 2002)

1.4.4.4: L- Pan roofingThe pre cast full span RC L-panel is of section L. The L- panels are supported on parallel gable walls and are used for sloped roof of a building. The RC units can be cast with simple timber/ steel moulds and are easy for manual handling with simple lifting and hoisting gadgets. L-Panel roofing is quite lighter in weight, economic in construction and sound in performance and durability. In addition to roof, the Lpanels can be used for making loft, cooking platforms, parapets and many other minor elements of buildings and structures. The techniques has been used widely in many mass housing programme in the country. (figure:10) (R.K.Garg, 2008)

1.4.4.5: Ferro Cement Roofing Channels:Ferro is an innovative term used to describe the latest technology where the term ferro stands for steel or iron and cement stands for binding and cementatious materials. Salent features Speedy installation no shuttering required 30% cost reduction over RCC roofing. Lower dead load on walls. Usable as an intermediate load.Raw material:Cement, fine aggregates (10mm and below), sand , steel, chicken mesh, welded mesh.

Figure2.2

1.4.4.6: Ferro Cement C- Beams/Rafter:For structural application as beams in roofing. It is cost effective prefabricated technology, it reduces the construction time and simple technology. Here two C beam joined in opposite direction makes an I beam.Properties of product: compressive strength 250 kg/cm2Raw materials ;Cement , sand , aggregate , steel, plyproplyne, fibre,admixture, wielded mesh.

1.4.4.7: Filler Slab Technique:The filler slab technique is based on the principle that for roofs which are simply supported, the upper part of the slab is subjected to compressive forces and lower part of the slab experience tensile forces. The filler slab is based on the principle that for roofs which are simply supported, the upper part of the slab is subjected to compressive forces and the lower part of the slab experience tensile forces. Concrete is very good in withstanding compressive forces and steel bears the load due to tensile forces. Thus the lower tensile region of the slab does not need any concrete except for holding the steel reinforcements together.Therefore in a conventional RCC slab lot of concrete is wasted and it needs extra reinforcement due to added load of the concrete which can otherwise be replaced by low-cost and light weight filler materials, which will reduce the dead weight as well as the cost of the slab to 25% (as 40% less steel is used and 30% less concrete) The filler slab is a mechanism to replace the concrete in the tension zone. The filler material, thus, is not a structural part of the slab. By reducing the quantity and weight of material, the roof become less expensive, yet retains the strength of the conventional slab. The most popular filler material is the roofing tile. Mangalore tiles are placed between steel ribs and concrete is poured into the gap to make a filler slab. The structure requires less steel and cement and it is also a good heat insulator.Conventional tests by different institutions and laboratories has proved the load bearing capacity of filler slab and found it no less in performance from the conventional R.C.C. slab. Since filler roof tiles are firmly bonded to and covered by concrete, it does not collapse under the impact of say, a coconut falling on the roof. Figure 2.41.4.5: Opening In The Form Of Arch With Local Materials:Arches are an economical and aesthetic means of spanning openings. Arches can be a cost effective alternative to the lintels. The traditional RCC lintels which are costly can be replaced by brick arches for small spans and save construction cost up to 3040% over the traditional method of construction.

Fig 2.5

1.5: COST EFFECTIVENESS OF USING LOW COST HOUSING TECHNOLOGIESThe construction methods of walling and roofing are selected for the detail cost analysis based on available resources from the interviews. Table 1 and Table 2 summarise the cost analysis of the traditional construction methods and the low cost housing technologies in the case studies for walling and roofing respectively. It is found that about 26.11% and 22.68% of the construction cost, including material and labour cost, can be saved by using the low cost housing technologies in comparison with the traditional construction methods for walling and roofing respectively. Suggestion for reducing construction cost in this paper is of general nature and it varies depending upon the nature of the building to be constructed and budget of the owner. However, it is necessary that good planning and design methods shall be adopted by utilizing the services of an experienced engineer or an architect for supervising the work, thereby achieving overall cost effectiveness. labour cost, can be saved by using the low cost housing technologies in comparison with the traditional construction methods for walling and roofing respectively. This proves the benefits and the trends for implementing low cost housing technologies in the industry. Table 1: Cost analysis of the traditional construction methods and the low cost housing technologies used in the case studies for 1m3of walling (Works Department, 2002)

Table 1: Cost analysis of the traditional construction methods and the low cost housing technologies used in the case studies for 1m3of footing (Works Department, 2002)

NoItemUnitRateConventional brickworkRat-trapbonded brickwork

(US$)QuantityAmount (US$)QuantityAmount(US$)

Materials

1BricksNo0.02350.007.00284.005.68

2Sandm30.320.280.090.170.05

3Cement (10kg bag)No6.170.674.130.402.47

Labour

1Mason (highlyNo1.700.350.600.350.60

skilled)

2Mason (2ndclass )No1.491.051.560.801.19

3Unskilled labourNo1.062.963.141.962.08

Add 2% tools and plant charges0.340.25

Add for scaffolding- superstructure: 0.42/m30.420.42

Total (per m3)17.7113.08

Savings26.11%

Table 2: Cost analysis of the traditional construction methods and the low cost housing technologies used in the case studies for 1m3of roofing (Works Department, 2002)NoItemUnitRateConventional slabFiller slab

(US$)QuantityAmount (US$)QuantityAmount(US$)

Materials

1Concrete, includingm338.61.0038.60.8030.88

labour

2Reinforcementton36.120.8028.890.3813.72

3Steel cutting, bendington3.870.803.090.381.47

4Mangalore tilesNo0.06N/AN/A65.004.14

Labour

1Mason (2ndclass )No1.49N/AN/A0.200.30

2Unskilled labourNo1.06N/AN/A0.800.85

Add 2% tools and plant charges0.110.11

Total (per m3)84.3265.20

Savings22.68%

1.6: CASE HISTORIES IN INDIA DEMONSTRATIONS CONSTRUCTION USING COST- EFFECTIVE & DISASTER RESISTANT TECHNOLOGIES BMTPCS INITIATIVES BMTPC has been promoting cost-effective & environment- friendly building materials & construction techniques in different regions of the country. During recent past the council has been laying emphasis on putting up demonstration structures utilising region specific technologies . Such efforts for demonstrating innovative technologies have created a much better impact and helped in building up confidence and acceptability in private & public construction agencies, professional & contractors. Details of the major projects handled by them are given as under:-

1 Demonstration housing project at laggerre , Bangalore, Karnataka.

Project profile name of scheme: VAMBAY-ministry of HUPALocation of site: laggere, BangaloreNo. Of units: 252(ground +2)Built up area of a unit: 252 sq.ftUnit consist of : 2 room , 1kitchen, 1 bath room, 1 WCCost per unit: Rs 60000Cost per sqft: Rs 218/-Nodal state agency: Karnataka slum clearance board

Technology and specification1. Foundation: Random rubble stone masonry2. Walling: Solid concrete blocks for 200 mm thick walls Clay brick of partition wall RCC plinth band for earthquake resistance3. Roof/ floor RC filler slab using clay brick as fillers in ground RC slab for second floor IPS flooring4. Doors and window: Precast RCC door frames Coir polymer door shutters Steel sheet window shutter

Laggere, Bangalore, karnataka

Figure 2.6

CONCLUSION

The dream of owning a house particularly for low-income and middle-income families is becoming a difficult reality. It is necessary to adopt cost effective, innovative and environment-friendly housing technologies for the construction. This paper examined the cost effectiveness of using low cost housing technologies in comparison with the traditional construction methods. Two case studies in India were conducted. It was found that about 26.11% and 22.68% of the construction cost, including material and labour cost, can be saved by using the low cost housing technologies in comparison with the traditional construction methods for walling and roofing respectively. This proves the benefits and the trends forImplementing low cost housing technologies in the industry.

REFERENCE http://www.gharexpert.com http://www.fs.fed.us http://www.greenstone.org http://manajemenproyekindonesia.com/ http://sepindia.org/ http://lauriebaker.net/ Low cost housing- an analogical study of the current practices & technologies by- vastu shilpa foundation www.wikipedia.com

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