Housing Sector In Fast Developing Cities Construction Essay

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Architects ego can be characterised by Ego Fuel formula which is comprised of Money, exposure, and praise. While architects work tends to be intellectual and theory-driven, many architects are seeking big-budget commissions that will allow them to make dramatic, self-expressive statements. The problem of ego has affected many architects and other building professionals as the result many students and training architects are inheriting the same ego, they work hard, and looking for big projects for self expressions and exposure, making dramatic money and also to be praised and distinguished.

"Regard it as just as desirable to build a chicken house as to build a cathedral"

By Frank Lloyd wright.

Architects are losing control of built environment and the world at large while busy working hard for distinguish themselves ,their carrier and for money, they have left behind poor and people in need who are majority in developing countries.

The architect's ego and ignoring housing for poor people in cities is the main reason why architecture is falling to change the world, this can simply be seen from the rise of unplanned settlements, poor houses, slums and pavement dwelling which do affect the life of every individual living in urban areas. Poor housing has tarnished many cities and reduces them to dumps, and there is poor sanitary condition which causes widespread of diseases like malaria, cholera and typhoid.

Many architects have distanced themselves from prefab and industrial systems of construction perhaps they are finding themselves in difficult situations imagining works of their hands getting produced in factories. They used to see and feel their works on progress, one brick after another, through traditional systems passed down from generation to generation which are inefficient in terms of quality and quantity in contemporary construction industry, as the result there is high housing demand and supply of less quality housing unfit for human habitation.

Identifying the need

World cities are faced with poor quality and very expensive houses; there is high demand for housing especially in developing countries and fast developing cities,.

High population growth in urban areas with scarcity of building professionals is a big challenge in improving urban settlements and peoples living conditions

High construction costs prevent low income people from affording houses, as the result fast developing cities are facing massive expansion of slums and unplanned settlements

The problem of housing shortage and poor housing quality need special attentions. The world has changed by revolution of science and technology, the construction has move to the higher stage of science and technology. However architecture is still lagging behind with primitive ways of onsite constructions inherited from ancestors, the ways which are very expensive, inefficient in terms of time consuming and quality, these ways which have proved failure as far as housing is concerned. It is time for architecture to go along with the changing world to solve housing problems, the time bomb waiting to explode.


The intention of this dissertation is to look some ways in which architecture might re-engage with prefabrication to find the best approach that will be better solution and that will reduce barriers to provide modern and green houses by considering its concept of authorship as an art form, production methods, marketing and distribution as well as construction.

The aim is to bridging the gap between industrial technology and construction sector especially in existing in housing sector.


The study will look on how architects ego can hinder housing access to the poor

The study will look on how primitive on site construction systems failed to solve housing shortages

The study will analyse how prefabrication can contribute solving housing shortages and other related problems in developing cities.

The study will cover some of the prefabrication methods , systems and process available for housing sector from designin,factory level, transportation and installation

The study will look briefly on the success, achievement and the contribution of prefab housing in the construction sector in different periods

The study will use case study to show in some of the systems which can be adopted in housing construction, prefab advantages and disadvantages in construction sector.

The study will make comparison between prefab construction and conventional ways of construction to give building professionals wider options to choose from both systems


Time restrictions limit the study to delve much deeper into history and evolution of prefabrication housing. Time also restricts the study to look in details how buildings are manufactured at the factories and also only selected prefab systems of constructions will be covered due to time restrictions.

In india prefab housing is at its early stages in terms of technology and production, much of the literature and examples are taken from western world where prefabrication in housing sector is more successful for long time now.

The foundation of this dissertation will based on existing books and internet sources as second sources of literature and surveys from websites and social forums and fro primary sources, these sources might present people's ideas and reaction on prefab. Therefore will not be responsible for the factual errors that may have been committed by the source.


Literature survey 1

Books, journals, and websites are sources to be used in surveying, examining and collecting information of prefabrication housing especially on terminologies, construction techniques, materials, data and methods used. This stage will use also social forums, journals and brochures written on prefabrication available. At this stage reaction of the society toward prefab will be understood.

Live/oral survey

At this stage prefab building professionals will be used as the source of information, the discussion will mainly base on how prefab and traditional on site construction can be integrated to form hybrid architecture.

Case studies

The case studies of prefabricated house and hybrid house will be used to analyze the types of design, the module used, the degree of prefabrication used, time and cost of constructions, challenges faced during the construction and how does the house respond to climatic conditions and human comfort.

The comparison will be made to show the differences in time, cost and quality between prefab constructions and conventional/onsite constructions.


Architects if want to solve the housing problem should allow Industrializing the housing sector, new construction technologies with other systems inherited of site construction together will increase the quality, efficiency and quantity of houses in cities and rural areas. It is time for architects to train industries on how to produce their work and put their ideas into reality:



The Origin and the rise of prefab housing

Although prefabrication of buildings goes long back to the early civilizations where Prefabricated stones were cut and curved in specific sizes and pattern to construct pyramids in Egypt and temples and arenas in Greek, it was until 20th century, the first prefab house appeared in 1920s, the wheel house or trailer which was basically a house on wheels when, the idea behind was to have a mobile home which could move with all important technical installations and furniture. Major difference which can be seen from a contemporary portable house with the wheel/trailer house is the stability, electricity connection and size. Technology development influenced evolution of Wheel /trailer houses to prefab houses by modifying their design in terms of stability, function, aesthetic and size, as the result the production was no longer targeting constant travellers only but also permanent dwellers.

In 18th century the industrial revolution in Europe brought rapidly technological expansions with economic growth. Commercial and industrial development with increase in

Science and technology had impacts in construction industry, new materials were discovered and the use of steel and glass and concrete spread all over the world. The prefab movement might consider the WW2 as a blessing in disguise, Millions of people lost their lives, houses and properties .Many cities were destroyed by fires that man began to develop.

The ending of World War II was the beginning of the war against time, and shortage of labour with high demand of rehabilitating settlements and recreating new houses. The destruction of cities, and the coming home of war veterans influenced the demand of cheap and affordable houses within a short period of time. The time was not enough to use tradition on site constructions, the only option on the table was to turn towards factory prefabrication to produce mass housing in short period of time. Prefab at this stage stopped looking difficult and complex structural requirements, simple roof with wall structures were developed.

In 1960s the prefab housing design and construction was influenced by the demands for comfort from clients .The design considered functionality of the prefab housing, prefab was accepted, approved and got full licence from architectural societies and started the competition with conventional onsite constructions. Since then, prefab housing is considered safe that is to be built according to all building regulations.

Prefab evolution lime line

The timeline shows Prefabrication achievement and factors for its development

Chapter 3


Prefab [1] is the process of making a building or part of the building away from the final building site (in factories) is referred as prefabrication or prefab. Prefab could be a module manufactured offsite and towed to the building site, it could be a home manufactured offsite in panels that then get shipped to the building site where they are snapped together. Prefab is also known as offsite building production.

"Prefabricated home is one having walls,partitions,floors,ceilings and a roof composed of sections or panels varying in size which have been prefabricated in a factory prior to erection on the building foundation" …..Albert F. Bemis [2] 

"Prefabricated houses are dwellings manufactured off-site in advance, usually in standard sections that can be easily shipped and assembled. Some current prefab home designs include architectural details inspired by postmodernism or futurist architecture" [3] â€¦.. Amazon .com

Types of prefabrication

Offsite/Factory prefabrication

This is when prefabrication of building elements takes place in a plant or factory and then the prefabricated material is to be transported to the construction site for assembly.

Raw materials are tested before starting further prefabrication procedures to ensure maximum quality of the end products. The factory is having controlled weather and other conditions like temperature, humidity wind, quality and production speed. Skilled labour is employed there high degree of surface finishing and quality.

Among the leading factory prefab firms in the world is Chinese firm BSB [4] which is currently producing high efficiency of 93% factory prefabricated buildings, whereas the current world's highest is only 40%.Only 7% [5] accounts for onsite installation at BSB. All Building elements including flooring, ceiling, embedded Shafts for ventilation, water supply systems, drainage systems electricity and lighting systems, beams, diagonal bracing, doors, windows, walls, bathrooms, kitchen and pillars are nicely parked on the main body after prefabrication process at the factory, ready for shipment to the site for installation.

2. Site prefabrication

This occurs when a plant is shifted to the site for prefabrication. Prefabrication is happening either at open spaces or in temporarily developed structures. The production is much slower in onsite prefabrication compared to factory one. Large machines cannot be transported to the site and some time very expensive. Also site prefabrication may stop due to effects of weather conditions like rain and sun. Since there is less or more controlled weather condition, building elements might be affected by local weather during prefabrication.

The advantage of site prefabrication over factory prefabrication is that there is no requirement of large volume trucks in transporting building elements to the construction site.

An example of site houses prefabricated and assembled on the site designed by TYIN Tegnesture, bolts were used to ensure precision and strength. The flip up roof designed to allow natural ventilation effectively while collecting rain water for uses.

Prefabrication methods

1: Two Dimensional Panels

The prefab panel system is one of the methods of making off site house, where the factory is producing walls of the house in form of panels designed to meet the required standards of the given project. Panel units which are produced in the factory are transported to the site for assembly to produce the finished structure.

Open panel system

The most common used approach is to use open panels, or frames. In open panel system, electrical wiring, plumbing and other services like insulation, external cladding and internal finishing are being done on site.

Closed panel system

Another used approach is closed panel system which is more complex and involves more industrial fabrication .building services like plumbing, electrical wiring, lining materials and insulation are installed inside panels at the factory. These panels may also include windows, doors, internal wall finishes and external wall finishes and


Modular house production process

A prefab module is a closed element or part of a building, its floor, walls and ceiling were pre-assembled in the factory. One prefab module may include several smaller rooms installed all windows and doors.

95% of the interior finish of the rooms is completed at the factory [6] including installation of ceramic tiles and floor coverings, most of exterior finishing works and house services like piping and cable systems,plumbing,ventilation,security alarm, fire sprinkler systems are completed also before the module is transported to the construction site. Other important installation includes all bathroom fixtures and fittings, kitchen and home appliances.

For transportation and factory standards, there are limits for dimensions of the module. An example is from Kodumaja prefab modules which are having dimension limits of; width - up to 5.3 m, length - up to 14.5 and height - up to 3.8 m. [7] 

From the Factory, produced prefab modules are transported to a construction site where are mounted on the foundation to form a single building. The transportation of module is done by Trucks and ships.

The building may consist of several prefab modules but commonly the individual houses are having 2-4 modules and multi storey houses have no limitation of number modules. The typical weight of a prefab module: 8-16 tons.

Time required mounting one prefab module on a completed foundation: 20-60minutes.

The construction techniques for strengthening modular housing include:

1. Window and door casings reinforced with metal spines in corners.

Drywall bonded to wall studs and ceiling joists with supper adhesive

Larger sheets of dry wall used on walls and ceilings

Separate first story ceiling and second floor system s on two story houses

Floor sheeting glued and nailed

Flush basement ceiling with main carrying beam built into floor systems

Double or triple perimeter floor joists used at marriage walls

Modules joined together at marriage walls with bolts in basement and attic

Corners of perimeter floor joists strapped

Double rim joists front and back of house

Factors contribute the quality of modular houses

Closely supervised and trained workmanship

Larger and more powerful equipments

High precision assembly jigs are used

Construction activities at protected and controlled climates

High protection of stored materials and modules

High construction standards


Before modules are transported from the factory to the construction site, the construction site is required to be cleared and prepared, to receive modules. All obstructions like trees, boulders, and power lines should be clear to allow the tractor trailer, vehicles or cranes to have access to the foundation location on the construction site.

According to modularcouncil.org, the route of travel from the nearest town to the site and site access should have the following features:

Minimum road width: 15'-0"

Minimum overhead clearance: 14'-0"

Minimum Power line clearance: 15'-0"

Maximum carrier axle clearance: 14"

Maximum slope on access ways: 12" in 20'

Minimum bridge weight limit: 15-tonne

The site should have two 30 feet x 60 feet areas cleared for use by the crane and transporter with reasonable access from the road

Transportation challenges to modular housing

Modular houses are built out of modules which have limited dimensions approved for transportation, usually  16' wide x 62' long, this creates design limitations.

Transportation of modules to the construction sites is very expensive, large vehicles are needed and in some cases special permits and escort vehicles are required.

Before manufacturing a prefab house, local transport codes should be checked.

Site works

Before the modules are brought to the site from the factory for installation, the foundation should be completed. Once the site preparation, clearing and foundation are complete, the modules can be transported to the construction site .At the site, modules are lifted from trucks to the building foundation, bolted to each other and to the foundation

Site works are starting as soon as the manufacturing starts at the factory, once the manufacturing process start, the land is prepared, graded and the foundation is poured. There is no need to wait one process to begin the other as the result; a considerable amount of time is getting saved.

Once modules are installed, finishing works like trim works, installing cabinets, installing HVAC systems hooking up plumbing and electrical systems can start, but in many most cases plumbing, electrical wiring, dry wall,cabinets,flooring,ceiling,,bathrooms fixtures are getting installed at the factory level to save onsite works

and maximizing quality and finishing precision and efficiencies .When modules are lifted up by cranes and bolted to the foundation and with each other and with the roof ,then the house is completely installed, closed up and secured.

Remaining finishing works like repairing any damages happened during transportation and during installation or any missing finishing will be taking place in few weeks the house is considered ready for occupancy and prior to the moving in the local building inspector will make a final inspection and issue an occupancy permit.

Site work steps (1-5)

Source: profabhomes.com

Methods used to move modules to the foundation

The process of moving the manufactured house from the street and onto its foundation most unique on-site activity which distinguishes Prefab houses from the site-built house. The process also is the most the most potentially hazardous in the construction activities to the safety of both the building and to the construction workers at the site. Some of the commonly used methods are:

Backing the module or pulling the it over partially completed foundation walls

Using roller systems to move the house over full foundation walls or

Placing the home with a crane.

Site assembly

Source: texasgulfcoastonline.com

If the foundation of the house is not recessed, the manufactured house should be delivered directly over its site upon arrival. Rollers can be used to push the manufactured house sideways over full foundation walls and finally locate it within the excavated pit. If the foundation is built up on a sloping lot, crane will most likely used to lot up the house to its position.

Chapter 4

Contribution of prefab in contemporary housing

Among the benefit of prefab technologies is their ability to reduce construction cost, construction time, reducing defects, improving health and safety during construction and after construction. The major benefits of prefab are time saving, quality control and minimizing the construction cost. Other benefits are proper use of building materials, efficiency and productive use of labour, however the system can be considered expensive and capital intensive in small scale projects, therefore it is perfect for mass production and economic feasibility is assured for large scale projects.

The research shows that prefab construction technique, technology and materials save 35% construction time and more than 40% of construction cost when compared with conventional systems................Sharma Shibani

Construction Time in prefab

The construction time is taken as the period required for work on a building Contract. (MacLean and Scott, 1995). Prefab technologies have the benefit of saving construction time from the date of site possession to the date of handover the project. (Baba, 2009). This means that the total time taken for offsite production with that of onsite assembling is lower compared to the total construction time when onsite conventional ways of construction are used to the particular project.

One of the methods used to save construction time in prefab is by overlapping the offsite and on site activities (Baba, 2009).the good example is that while working with prefab, the foundation and main structural systems can be constructed onsite at the same time when building elements are undergoing prefabrication process and pre assembled offsite. The overlapping construction activities cannot be done by traditional onsite construction. Also prefabrication is being done by machine at a controlled speed which is higher than human production speed.

Prefab uses short period of time with predictable completion dates since large percent of production is being done under the controlled climate and free from local weather and distraction.

To benefit time saving in prefab system, prefab should be included in the process of design at concept design stage (Reid 1999) [8] to avoid lack of compatibility which might increase the construction cost. Changing the design on the ongoing project might introduce complications for realignments components delivered to site fit a specific set of dimensions. In prefabrication greater precision and good supervision are required to reduce adjustment and realignment.

Construction Cost in prefab

Construction cost are the total costs incurred for the work required by the plans and Specifications for a specific construction project including labour cost, material cost, equipment cost, and Services (Baba, 2009).

In prefab construction cost depending on the type of technology used, however, many prefab technologies have been verified to be more expensive compared to the traditional type of construction. The construction costs are usually between 10% and 30% more in prefab. ((Abiola O. Baba,Rotimi Joseph) [9] , Naoum Shamil [10] )

The benefit of using prefab is to reduce the preliminary costs in setting up of the site in construction project along with reducing construction duration which eventually results to further savings for the construction projects. Prefab also is having the benefits of minimizing the level of onsite based human resources compared to the traditional constructions. Prefab employ less people on the site for lesser time therefore there is significant reduction of the need of services facilities for canteens,toilets,site offices, changing facilities electricity, water and costs for maintenance.

Prefab also reduces onsite construction works, big percent of the project is done offsite under the controlled climate and quality. Through reduction of onsite program contractors and clients have the benefit of lowering significantly overall hires costs for the particular construction projects. Construction expenses and labour costs contribute in cost reduction in prefab systems.

Although the prefab production saves some construction costs, the big challenge which usually affects the total construction costs is transportation of prefabricated modules which require much larger capacity transport vehicles compared to the traditional approach. As the results, the transportation generates greater costs, especially if the factory is located at long distance from the construction site.

Construction cost evaluation in prefab and traditional systems

The effects of construction costs in prefab sector was seen in AUM house project built in New Delhi, India, in 1999 trade expo.The prototype of the house was 23m2 and weighed 22.5 tons was prefabricated at Auroville and transported by lorry at a distance of 2,900 Km between Auroville, Tamil Nadu, and New Delhi in 5 days. The transportation cost was higher than the cost of the house itself. (EARTH-AUROVILLE, building research institute)

Price per square foot.

The cost of the landsite preparation and foundation construction are more or less similar in both prefab and convention onsite construction, Therefore to make the comparison of construction cost between prefab and conventional homes is simply

1: selling price of the structure, measured per square foot of floor area. In 1996 in USA, the average price per square foot of manufactured homes was $27.83, 47 % of the $59.25 price per square foot of conventional single-family homes.

Tracks average sales price per square foot of both types over the period 1980-1996 in constant 1996 dollars.

Source: huduser.org

Construction Quality in prefab

Construction quality can be defined as a high degree of excellence of the building elements, building and the whole project in general. Prefab provides the construction industry with improvements in quality since the production takes place in controlled environment. Therefore the quality of prefab in more when compared to the tradition ways of construction which lack better control.

Prefab production is free from extreme temperatures and climates of the local surrounding especially during winter and summer seasons, rain and wind. Building in factories also offers another advantage of improved working condition and lighting to construction workers compared to the conventional ways of construction where staffs are forced often to use temporary lighting and at poor condition, as the result the conventional onsite construction has high risk of substandard and less accuracy works.

There is enough space in the factories to enable labourers to walk around the mould and enabling them to access all parts of the object under construction, as the result factory solve any problems which might be caused be vision or accessibility in onsite construction.

However, the quality of the finished products could be at risk of damage during Transportation and installation which can result to serious Effects on the progress of the whole project hence poor quality of the finished product. However precaution and transportation management in prefabricated products are easier to avoid or minimizing damages compared to onsite ways of construction.

An example is the transportation of prefabricated and pre stressed building elements of AUM house, by lorry at a distance of 2,900 Km between Auroville, Tamil Nadu, and New Delhi in 5 days. Out of 2280 blocks 8 were broken, ferro cement pieces had little hair cracks. (EARTH-AUROVILLE.com)

Prefab has no ability to transform poor design but if the building is designed and Executed correctly prefab can achieve high quality under the factory-controlled environment therefore reduces damage from handling and storage onsite, and limit risk of damage

Sustainability in prefab

Sustainability in 1987 was defined as "development which meets the needs of the present without compromising the ability of future generations to meet their own needs". [11] Sustainability in construction can be measured through the use of energy, resources, materials, water, pollution, waste, health, well-being and the effects of the project to the surrounding environment and to the globe. Prefab can offer benefits of environmental, economic and social sustainability to the construction project through:

Less waste production

Less packaging

Reduced environmental impact during the construction process

Less impact on surrounding area

Prefab process control the amount of waste and pollution generated into the environment since production processes take place in the factory, at a controlled and regulated environment in which the levels of dust and noise can be extracted from the atmosphere. Prefab also has the advantage of recycling waste materials from construction, industries and many other sectors, which can then be used for other construction projects.

Prefab has the potential of producing 50% reduction for water used during the construction of a typical house, 50% reduction in the quarried materials usage on site can be achieved and 50% reduction in energy consumption (EC Funded Sustainable Construction Project,

1999). [12] 

If other prefab project and other construction project can save the same amount of resources, then the effects on construction industry to the environment will be highly reduced. European Sustainability Group Report, (2001) [13] identified six indicators for measuring sustainability in construction projects as:

Operational Energy Use

Embodied Energy

Transport Energy


Water and

Species Index per Hectare

Among six indicators, prefab has a negative potential effect on transportation energy because the transportation process requires high capacity vehicles to transport the modules to construction site. High capacity vehicles require more fuel and emit large amount of carbon dioxide. However in other five indicators of sustainability in construction industry, prefab is having beneficial advantages compared to traditional ways of construction and therefore can generally be considered more sustainable.

The use of green and environment friendly materials [14] have been increased in contemporary prefab housing. Clients nowadays can easily select between different environmentally friendly finishes and wall systems, furthermore the design can be customized to the client's specific location and climate, making prefab homes much more flexible and modern than before.

Economic Aspects in prefab construction

The EC funded a Sustainable Construction project called Future home (EC Funded

Sustainable Construction Project, 1999). It sought to help EU States meet the social need

of affordable housing. The project aim was to build up a pool of data on building

prefabrication from low to medium rise housing, and was of the hope that it will provide

the basis for developing sustainable and adaptable building concepts using prefabricated

technology. The objectives of the project were to deliver: 30% reduction in construction

costs; 35% reduction in construction time and 60% reduction on defects on completion

(BRE, 2003).

Social Aspects in prefab construction

Although prefab is quite successful in non-domestic buildings like retail developments, fast food restaurants, and hotels, the technology is totally dominated by traditional ways of construction in housing industry. Prefab is still not the first option on the table whenever it come to housing construction sector, especially in developing countries probably due to lack of technology or lack of knowledge on how prefab systems work or both. There is no serious social problem of prefab construction has been reported so far.(BRE.2003) [15] 

Health and safety factors n prefab

Benefits of prefab in health and safe factors can be measured through the following process:

prefab employ few people at the site, by doing so it reduces health and safety risk

much of prefab works are done at the factory, Offsite reduces work at height risk

Health and safety is easier to control in a factory setting than at the site.

Advantages of prefab housing

Using prefab means doing less work on site and as the result less production of noise, dust, pollution and disruption at the site.

Housing construction is happening at improved working unlike conventional ways of constructions which takes place at an uncontrolled and comparatively harsh weather.

Prefab offers more sustainable solutions to residential buildings

The quality of work is much higher when the building elements are made in stable and controlled condition like factory.

Prefab in housing improves uniformity and brings unskilled labour inside where work is closely supervised monitored and also controlled.

In housing prefab, Materials are used more efficiently, safer from climatic damage and can be reused.

Prefab helps to reduce site operations on projects within or adjacent to operational Facilities and institutions like existing hospitals and schools.

The use of fly ash in prefab in concrete increases its workability and improves its thermal performance.

The prefabricated alternative to roof Construction removes the problems of timber molds and shuttering

Materials tested and modifies under controlled condition in the prefabrication housing can help to mitigate material failures.

Prefab housing emphasizes recycling and reuse of materials for housing construction. An example can be taken from Fly ash which is captured from the coal burning in the process that produces electricity.fly ash then is used to produce durable and stable building materials in factory .Fly ash replace traditional clay bricks which do not contain expansive soils hence cause walls and floors to crack due to temperature and humidity.

Prefab needs less site storage space

Disadvantages of housing prefab

many fabrication reliance on minimal skills, and prefabrication isolated working environment disconnect with the surrounding community and leaves little chance for continued fostering of personal and collaborative skills in culture, tradition and community building.

Developing countries lacks prefab technologies; there is little room for not depending on developed countries for technology transfer. Housing prefabrication technology transfer, including materials and digital tools, can negatively affect the environment, Economy and culture of the receiving country

Housing prefabrications depends on shipping or transportation of building elements from the factory to the site which increases the construction of the house, the cost increases as the distance increases.

Housing prefabrication employ few number of skilled labour, therefore do not contribute much in solving unemployment problems facing developing countries

Prefab technologies are transferred from developed western countries; therefore do work better in western designs rather than vernacular designs in developing countries.

Challenges prefab housing

The difficulties in technology transfer

The cost of machinery and materials for housing production.

Housing prefab factory needs big capital and investment

Lack of political will and support

Lack of knowledge on prefabrication by clients and building professionals like architect, engineers and contractors.

Automated design and construction cultures that promote the separation of fields.

65% of construction firms employ less than five people [16] , therefore making investment in technology difficult, as the result many operations are based on traditional ways of onsite co



"I like to see a home like this, a home connected with people's thoughts and work, things they love."

By Dewitt Bodeen (1908-1988),

Planning and design of prefab housing features include foundation type, exterior and interior finishes, roof pitch,windows,doors,wll heights and building services like stairs and other building appliances influence the cost and sales of the house. Basic features are often targeted at the low income people while dramatic features and complex designs for high income and luxury people.

Designing Building height should consider regulations imposed transportation of goods on public highway and other challenges of production at the factory. These challenges have largely constrained the varieties of floor plan designs in prefab housing. Onsite built houses are comparatively larger with big living rooms, dining rooms, kitchen and bathrooms.

Other factors which influence the wall and ceiling height in prefab include economic and aesthetic reasons. From an economic standpoint, the wall height has effects on material

Design and planning

Image-1, 2, 3, and 4 credits: andrewmaynard.com

and lobor costs as well as increase heating and cooling expenses. Another stand point of view is energy, shorter walls than 8feet height with lower ceiling height has lower surface area exposed to the external harsh environment, that means less loose or gain heat, therefore shorter walls will reduce cooling and heating energy needed by a particular house.

However ceiling height of 9 feet should be considered for the interior part of the house to offer spacious open feel which is valued by many people.

Foundation design in prefab housing varies depending on the type of the house. Movable house one of prefab type is designed to be capable to move from site to site, therefore structural chassis is required to this kind of design to provide to provide stability in transport. Historically movable houses have been placed on non permanent foundations.¾ prefab houses at present are placed on blocks that support the entire structure of the house beneath the integral steel chassis. [17] Many prefab single family houses do not have heavy Foundations, predominately basements, crawl spaces or concrete slabs on grade. However other prefab house might have crawl and basement spaces.

Wall Height in New Conventional and prefab Homes, 1996

Source: NAHB Research Center, Lumber and Plywood Usage in HUD-Code Manufactured Housing, 1997.

Foundation Types for New prefab and Conventional Homes, in USA- 1996

Source: Beural of the census C25/96A

Prefab houses design uses standardized dimensions and room sizes, and differs significantly with onsite conventional design in room sizes and numbers. It should be noted that it is very important to involve factory advices during initial stages of design. Once the design is complete the factory production starts and at this level no major design changes is expected from the designer since only small change can affect the quality of the house.

Average Size and Numbers of Rooms in New Conventional and Manufactured Homes, 1996


NAHB Research Center, Lumber and Plywood Usage in HUD-Code Manufactured Housing, 1997.

Design and planning

All Image credits: andrewmaynard.com

2: Built with Structural Insulated Panels (SIP)

Structural insulated panels consist of an insulating layer of rigid polymer foam sandwiched between two layers of structural board of sheet metal, plywood, cement or oriented strand board. Structural insulated panels are having the same properties like an I beam or l column. The system is having different components of studs, joists, insulation, vapour barrier and air barrier and can be used for exterior walls, roofs, floors and foundation systems.

The structural insulated panels system assures maximum optimization of dimensional with structural qualities, however their material cost are comparable higher when compared with other panel systems. The structural insulated panel system gives higher insulating properties to the building envelope which leads to decrease in operating costs.

The good example of the prefab housing used the structural insulated panels system is a house designed by Alejandro Soffia, Gabriel Rudolphy,the house was built in 10 days with 40 split-level panels (21 cm x 488 cm x 122 cm) and 71 wall panels (11.4 cm x 244 cm x 122 cm). The structural insulated panels were exposed on the facade and fashioned as terraces on the third and second floors.

3: Module system production

The prefab house produced in the form of modules is commonly referred as a modular house. Modular houses are constructed entirely in factories and transported to their construction sites. The module production is taking place under controlled conditions, and must meet standards and quality-control requirements. The construction within the factory eliminates any possibility of weather damages and eliminates any possibility of water entering inside the house during construction.

From the factory, modular houses are transported to the site in form of block segments where they are careful assembled, by using cranes, into structures that can hardly distinguished from conventional onsite built houses. Climatic factors do not disrupt construction processes since the production takes place inside the factory. The quality of production, time efficiency; finishing and precision make modular houses famous in developed nation. However lack of technology and the initial investment are barriers for developing countries to adopt the system.

A study by FEMA found that modular homes withstood the wind and water from Hurricane Andrew better than most other homes in the area. They take less time to construct than site-built homes, are more energy-efficient, and generally cost less



"TheT30building is a prefabricated tower which has been designed to be highly sustainable both in construction and day-to-day running, with a heat recovery system and energy-saving lights throughout." [18] 

Project summary and contribution to prefab industry

30 floors hotel building with 330 hotel rooms and 700 beds

17338 (578 each floor)

The building is 93% factory prefabricated

200 workers

Onsite assembling 15 days

Factory process 45 days

Carbon dioxide emission reduction 2,000 metric tons a year due to savings in electricity

Pollution generated is 1% that of a standard hotel project.

Building was constructed with 1/6 of the material which could have been used to make typical building by using onsite tradition construction methods.

Ability to resist earthquake up to 9.0 magnitude

T30, the hotel has 315 standard rooms, 32 suites, eight large suites, two presidential suites, restaurant, bar, fitness center, swimming pool, underground parking space, and a helipad. [19] 

It is 30-storey prefabricated tower which was assembled in 15 days on the site [20] . The high speed of construction was facilitated by assembling many parts of the building in factory itself before shipping to the construction site. Although the building is not 'iconic' or 'landmark its speciality is based on speed of construction and its ability to resist earthquake up to 9.0 magnitude [21] which is in the same category as the one devastated Japan in 2011.The strength of the building was tested by tested by China Academy of Building Research.

The T30 is the hotel building 17,000 Square metres, was constructed by 200 construction workers in 360 hours

The structural stability and speed in construction where achieved since key structural elements in T30 building consisted of prefabricated steel and cement with the aim of reducing the amount of work required on the construction site and also to ensure that the completed building is extremely solidly-built.T30 Hotel was constructed by Zhang Yue of the Broad Group a Chinese construction company specialising in sustainable building.

To ensure sustainability, the building was constructed with 1/6 of the material which could have been used if onsite tradition construction methods were used instead. [22] T30 building is also boosted with the installation of quadruple-glazed windows with glass walls 150 millimetres thick for optimal insulation as the result heating and cooling

demands for the building were substantially reduced. The building also was installed energy serving lights to limit building impacts to the surrounding environment. The construction of T30 building was completed quickly and safely while respecting sustainable building practices. Despite of time constraint, the construction of T30 building lowered waste production and achieved high sustainability. According to Julia Jang, the vice president of Broad Group, 93% of the T30 building was completed in the factory and installation of building elements like lights and the kitchen sinks. [23] Factory process took 45 days, but there are benefits of spending enough time in the factory including reducing outdoor pollution and safety hazards. There was no welding or cutting and construction pollution generated is 1% that of a standard hotel project.

The T30 is considered as energy efficient, a part of four pane windows and 150 millimetre exterior thermal insulation. Jang believes these measures will lead to reduction of carbon dioxide emissions by 2,000 metric tons a year due to savings in electricity. [24] The building has positioned itself as a global leader in construction speed and efficiency without compromising on safety of its workers and residents.

Transportation of building elements from the factory to the construction site

Energy efficiency

BROAD sustainable building adopted not less than 30 different energy saving technologies including:

Thick thermal insulation of exterior wall and roof,

Multi-paned windows,

External solar shading,

Heat recovery fresh air,

LED lighting,

Power generation by elevator descending and


T30 building can resist earthquake of 9 magnitudes, [25] a team of 300 BROAD researchers has done many of testing, and then developed combined earthquake resistance system of light weight steel structure with diagonal bracing.

"China Academy of Building Research conducted earthquake resistance tests for 7-storey and 30-storey sustainable building simulators scaled at 1:4 & 1:10, and accurately verified that earthquake resistance of BROAD Sustainable Building is 3~12 times higher than that of conventional buildings in the world (Magnitude 6~7, 0.05~0.12g on average; Magnitude 8, 0.22g highest)" [26] 


The sustainability of T30 building is derived from

Earthquake resistance,

Energy conservation,

Air purification,


Material saving,

Recyclable construction materials,

Energy comparison between theT30 five star hotel with a traditional five star hotel of the same size. [27] 

All data from BROAD


Calculation basis: Converted primary energy/electricity: 4kWh/kWh, converted oil/electricity: 0.25L/kWh, annual. Lighting hours: 2000, hotel occupancy rate: 80%.

Compared with traditional buildings(including 5-star hotels), this hotel saves 8.8 million kWh a year in terms of the total energy consumption of air conditioning, ventilation, lighting, elevators, water pumps and others .

The saved energy,8.8 million kWh per year =880,000 litres of oil=2000 tons of co2 cutting=110,000 tree planting

Air quality comparison between the T30, 5 star hotel building and a tradition onsite built 5 star hotel of the same size

hotel building also uses the system of invented heat recovery fresh air system where there is heat exchange between outdoor fresh air and indoor exhaust air, the system recovers 70%-90% [28] 

Comfort comparison between the T30, 5 star hotel building and a tradition onsite built 5 star hotel of the same size

All data from BROAD

Earthquake resistance comparison between the T30, 5 star hotel building and a tradition onsite built 5 star hotel of the same size

All data from BROAD

From top, 17-22 floor, typical standard room and medium suite plans, 23-24 floor typical small and medium suite, and 25-26 floor typical small and large suite plans.

Photo credit: BROAD

Building life design comparison between the T30, 5 star hotel building and a tradition onsite built 5 star hotel of the same size

construction mode comparison between the T30, 5 star hotel building and a tradition onsite built 5 star hotel of the same size

l data from BROAD


The foundation construction is not included in above data. The foundation designed by SBB is similar to that of conventional buildings; the difference is only that it can be reduced due to light weight of the building.


5:1 Primary research with Hindustan prefabricated limited

Interview with mechanical engineer Santosh Kumar



How do you think of prefab?

Prefab is the production of buildings in factories

What can a client expect from prefab?

High quality with nice finishing building elements

Is Hindustan prefab limited making residential building and building elements?

The factory is producing buildings and building elements for residential and public buildings and infrastructure. It depends on the clients demand.

Why do you think your production is quality?

The factory is having laboratory to test all incoming raw materials and also there is controlled condition we are working on to make sure that the end product is getting high quality.

What the average life span of your buildings?

Due to the quality of our building elements, the life span is high, about 150 years

What is the cost difference between industrial building and onsite construction?

The cost is the same

What about efficiency?

Do you think prefab is sustainable?

What are the challenges?

Since we are working on machine and controlled condition, we have much higher efficiency in finishing and time saving

Yes, much more than site construction, firstly we make hollow concrete columns high have high strength than solid one and with little amount of materials. Secondly our building are having less weight therefore do not have much effects to the site and also higher life span Big challenges is technology transfer, we expect to borrow American technology since the country has advanced in prefab

But also we need loans to expand our investment and to open new more factories.

Prefab in to India

Developing countries are beginning to rely on housing prefabrication which has the potential of making quick and affordable houses but too much relying on manufactured homes might bring advantages as well as disadvantages to developing countries. The potential of housing prefab to increase Productivity and efficiency without sacrificing Housing quality, make it desirable method of construction in India and other developing countries which badly face deficiency of housing, and housing quality especially in fast developing cities. Prefab in India started with Hindustan prefab housing factory, nowadays known better as Hindustan prefab limited.

Hindustan prefab limited

Hindustan prefab limited is the government factory was set up in1950 few years after independence under the first Indian Prime Minister Nehru, which came after the split of India and Pakistan, the split displaced many people and caused suddenly high demand of houses in some cities. The Hindustan prefab limited was primarily for manufacture houses for displaced people from Pakistan, with the aim of satisfying high housing demand, values of better, cheaper and faster by using light weight concrete panels. Later the factory diversified its activities into production of pre stressed concrete electrical poles and railway sleepers.

The Hindustan prefab limited has different department for its different activities,

The department c-I deals with manufacturing of railway sleepers and electrical poles

The department c-II deals with manufacturing of railway sleepers and pre stressed bridges

The department Vayutan deals with manufacturing of autoclaved aerate cellular concrete

Rcc department deals with manufacturing of reinforced concrete products like fencing posts water tanks, pavement slabs, kerb stones, interlocking solid blocks for pavement and for retaining walls.

Wood work department which is dealing with manufacturing of doors and window shutters and medium density fibre board.

Production quality

According to santosh kumar,a [29] mechanical engineer at Hindustan prefab limited, the factory uses m40 concrete to produce building elements compared with m25 normally being used in India. According to him when all building parts are prefabricated, the life span of the building is above 150 years without major maintenance. The company is equipped with material testing laboratory in its premises. The laboratory is testing all the ingredients for manufacturing concrete as well as machines for testing not only large but also heavy concrete products. Hindustan prefab limited tests all construction raw materials before starting processing them to ensure maximum quality and durability of the end products.

Prefabrication impacts to housing sector

Amplified human energy to increase output

Increase levels of control,precision,accuracy and quality

Improved ergonomics for reduced fatigue and increased safety

Reduction of the mass of the material

Increased the strength of the material

Offsite customization of material

Installation flexibility to any weather conditions

Curing and cooling of material


Although a prefab house is not something new in India, still it is lagging behind; prefab systems can easily be seen in infrastructure constructions like metro, bridges and fly over

There is no political willing and support to promote housing prefabrication,

Prefab technology transfer is a challenge in developing countries. The cost of prefab house is depending much on the technology used.

Transportation cost is the problem facing prefab housing sector, An example is the transportation of prefabricated and pre stressed building elements of AUM house, by lorry at a distance of 2,900 Km between Auroville, Tamil Nadu, and New Delhi in 5 days. Out of 2280 blocks 8 were broken, ferro cement pieces had little hair cracks. (EARTH-AUROVILLE.com) therefore it is advised to locate the factory near to the serviced areas.

The cost of machinery and materials make initial capital for establishing the factory too big. That another factor that hinders the growth of prefabrication in construction sector.

Lack of knowledge on prefabrication by clients and building professionals like architects, engineers and contractors as it can be seen that prefabrication studies are not taught in most architectural schools; instead conventional systems of construction are taught and given much emphasis.

65% of construction firms employ less than five people, therefore making investment in technology difficult, as the result many operations are based on traditional ways of onsite constructions.

Prefab offers more sustainable solutions to residential buildings as recycled material can easily be used, also small amount of wastes are produced.

The quality of work is much higher when the building elements are made in stable and controlled condition like factory.

Prefab in housing improves uniformity and brings unskilled labour inside where work is closely supervised monitored and also controlled.

In housing prefab, Materials are used more efficiently, safer from climatic damage and can be reused.

The use of fly ash in prefab in concrete increases its workability and improves its thermal performance.

The prefabricated alternative to roof Construction removes the problems of timber molds and shuttering

Materials tested and modifies under controlled condition in the prefabrication housing can help to mitigate material failures.

Prefab housing emphasizes recycling and reuse of materials for housing construction. An example can be taken from Fly ash which is captured from the coal burning in the process that produces electricity.fly ash then is used to produce durable and stable building materials in factory .Fly ash replace traditional clay bricks which do not contain expansive soils hence cause walls and floors to crack due to temperature and humidity.

Material manufacturing is more predictable and serves to build more seismically resistant structures.


As explained in earlier chapters prefab is nothing new in housing sector. Many parts of residential buildings like ceramic tiles, machine made bricks, sheetglass,columns,beams,kitchen cabinets,doors,windows,and bathroom fixtures are manufactured from the factory and installed to the building at the site during construction, however major construction activities still depend on conventional ways of construction inherited from earlier civilizations. However these traditional ways of onsite construction have failed to solve contemporary housing problems.

Shortage of manpower-unlike during old civilization when construction labour was cheap and available, today's world is suffering from high cost of labour and shortage of building professionals. There is a need of industrializing the construction sector to fill the gap of labour cost and manpower shortage.

The rapidly population increase in urban areas and high housing demands are some of the factors which force the housing sector to re engage itself with factory produced building which are standardized and can be mass produced just like cars.

The increase natural disasters due to human activities and pollution need special attention in housing construction. There is need to maximize housing quality, strength and capacity to resist natural disasters like earthquake. Prefab housing has proved to be of high quality. Prefab also can utilize recycled materials, use less building material and produce small amount of waste which can be beneficial in contemporary housing for its resources sustainability.

Prefab housing lowers construction period for a given projects since more than one process can be overlapped. The prefab foundation is taking place while the factory manufacturing is going on. Also at the factory the flooring manufacturing processes do not wait for wall or ceiling to be completed. Machines are also working faster and more efficiently than men. There is no need to waste time on the site, increasing unnecessary costs and producing lesser quality works, it is time for architects and other building professionals to compare these systems and make integrity decision.

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