Role of Prefabrication in the Construction Industry to improve sustainability and economy of Civil Engineering projects

Abstract

With increase in labor costs, lack of skilled labors for different trades, demand for faster construction, increased considerations for safety and environment, and above all meeting these demands at an economic and reasonable price requires us to change the approaches we take to build our project. Prefabrication or modular construction is one such solution to all these issues which can help in building the project on time, safe, greener, and within reasonable cost.

This paper discusses the various advantages that are possible to achieve if we utilize prefabrication strategy on construction projects by replacing the traditional construction methods. The role played by prefabrication throughout the history of civil construction is also discussed in brief. It also focuses on some of the difficulties in its path which have been there that have hindered its application on a wide scale. The role of Owners, Architects, Engineers, Contractors and Manufacturers in resolving these issues is also discussed in this research.

Finally, two case studies are done to reinforce the advantages offered by prefabrication and modularization in the construction industry. Case Study of Fort Sam Houston Medical Education and Training Complex in San Antonio, Texas, and The Stack Rental Apartments in New York are discussed.

Keywords: Prefabrication, Modularization, Modular Construction, the Stack, Fort Sam Houston

Introduction

Prefabrication, a construction industry term, is used to describe a building or structural components that are manufactured in industrialized/factory conditions and then transported to construction sites to be assembled into a building, and civil engineering works. So, it is a process in that a whole structure or building or a component of it is completely fabricated at an offsite location. These offsite locations can be considered as equivalent to an industrialized manufacturing facility, where things are built in controlled plant conditions. The construction is done as per the same design, codes and specifications, and using the same materials as in the traditional onsite construction approach. The offsite construction process takes relatively less time than the tradition onsite construction method. These offsite fabricated buildings or components are then transported to the construction site and then erected in place using cranes. As these have to be transported from offsite location to onsite location, there is a limitation on the maximum permissible dimensions of these components that majorly depend on the ergonomics of the roads, and highways through that they will move. So, these buildings cannot be built in one piece, and thus, they are broken down into small and manageable components. These small and manageable components are termed as modules. When these modules are stacked together as per the plan, then they combine to form the whole building that provides same facilities, functionality, and comfort as its cast in-situ counterpart. These reflect the identical design intent and specifications of the most sophisticated site-built facility without compromise.

If we consider the structural strength and structural feasibility of the prefabricated buildings, then it is found that these buildings are stronger and more structurally sound than the convention onsite constructed buildings. This increase in structural strength can be attributed to the fact that each module of these buildings is engineered to independently withstand various loading conditions it

is expected to face during the transportation and erection phase. Once these modules are erected, combined and sealed together they act as an integrated unit that is structurally and ergonomically sound for the purpose it was constructed.

History

Prefabrication or Modular construction may sound like a new term to many, but this practice of construction has been used for a long time. Its roots can be traced to the Rome in AD-43, where the Romans used prefabricated building elements to build their forts quickly and efficiently. There was a continuous construction of forts and stockade in the Roman Empire. Romans understood the fact that these forts and stockades used a large number of same and repeating components. Thus, to expedite the construction process, the Romans started prefabricating standard dimensions of these components. Timbers were cut into specific sizes, grooves were also pre-cut ready for fast construction, and the blacksmiths made iron nails in all different sizes and shapes. All this factors combined helped the Romans build their bases with unbelievable speed.

Not only the Romans, but the Britishers also transported simple prefabricated houses by ships to their new settlements in the colonies to provide comfortable European Style living to its officers in these colonies. Prefabrication method also helped address British and European housing shortages during Post World War I era. And, again during the Post Second World War era, prefabrication came to rescue, as it alleviated the shortage of skilled labor in the midst of the population outburst due to the baby boom.

Among most iconic structures in the world, The Eiffel Tower was also a result of utilizing the method of prefabrication in the convention construction environment. Eiffel Tower was built as a temporary exhibit structure for the Centennial Exhibition in Paris in the year 1889 for the

celebrating the French Revolution of 1789. And, today, it is known as one of the most renowned structures in the world, a symbol of love and romance.

Figure 1: Gustave Eiffel

It measured 984 feet or 300 m in height and was the tallest building in the world for about 40 years. The title was then taken over by the Chrysler Building in New York City in the year 1930. The Eiffel tower consists of prefabricated iron parts that were mass produced at an offsite location. The different iron parts were manufactured according to the design drawing and specifications. These parts were then taken to the site and assembled to build a structure that is still considered as a symbol of the city of Paris and the country France. The 984 feet tall structure was completed in a time-period of just over two years with a menial investment of 8 million francs. The investment capital was earned in the first year of its construction as people throughout the world visited to witness this marvelous structure.

Figure 2: Crew that worked on Eiffel Tower

The labor force required for its construction was also very less, as it required only 300 workers to construct it. It is also considered amongst the safest construction project of the time, as there was only one fatality during its construction. Thus, Eiffel Tower is a structure that signifies modernity, progress in technology, and an important chapter in the history of prefabrication industry.

History of Prefabricated Construction in the USA

As previously stated, the Britishers shipped prefabricated houses to its colonies in 1600’s. And further during the gold rush in California, prefabricated readymade homes were transported to San Francisco from all around the world to provide cheap housing solution. In 1908, Henry Ford’s car

factory and the assembly line concept largely influenced the American Prefabricated house industry as Henry Ford’s Model T, the first affordable automobile, successfully demonstrated and established the technique of mass production to manufacture high-quality products at a lower cost. Many companies started to offer high quality, precut and prefabricated houses in various customizable sizes, styles and design. Thus, began a trend of “House by Mail” that was pioneered by Sears, Roebuck & Co. The company was able to sell more than 100,000 units of these houses during 1908-1940. A “house by Mail” kit included all the components required to make a home encompassing everything from lumber, nails and shingles to windows, doors and paint. The buyers also had the option to customize these homes as per their needs and desire. People could purchase these ready-to-assemble homes by placing an order through the mail. And these houses could then be shipped in boxes to any place that was accessible utilizing rail or other means of transportation. These homes were meticulously designed, and exceptionally tough and sturdy.

Figure 3: House by Mail by Sears, Roebuck & Co. of Chicago

With the advancements in the field of information technology and the interaction between the construction process and these technologies, has greatly influenced prefabrication and modular construction. Now, the industry is starting to develop more efficiently as the new technology has provided more options and flexibility. The advancements in the field of computer and digital technology have helped in the industry in both the manufacturing as well as the design process. The words like CAD, CAM, CNC, and BIM, that stand for Computer Aided Design, Computer Aided Manufacturing, Computer Numeric Control, and Building Information Modelling respectively, have become common words in the vocabulary of architects, engineers, contractors and manufacturers. They help in making a realistic model of the finished product in a digital format. This digital representation can be changed, tweaked and modified on a computer screen without the need of any physical material required. The Building Information Modelling (BIM) software has helped the architects and engineers to see their project clearly in a 3D Model, just like if it was constructed on site, and thus, they can understand the various challenges they might face during the actual construction and find solutions for the same. BIM 3D models play a very vital role when the building components are produced in a factory setting as it allows the production team in the factory to see any individual building component from a whole building model. With the introduction of BIM, prefabrication is now a day viewed as the future of the construction industry.

Why Prefabrication

There are many factors that can be attributed to causing a positive impact on the use of prefabricated structures in building and civil construction works. Some of these factors can be summed up as follows:-

As discussed earlier, there has been a sporadic demand for prefabricated buildings and facilities throughout the history during British Colonization, World War, and Post World War era

With the ever-increasing population, there has been a rapid development in the residential as well as the commercial field that demanded faster construction techniques

In the times of distress when natural disasters like earthquake and cyclones etc. occur, they cause huge damage to civil property and buildings. It becomes necessary to restore them to bring back the life of the people to normal that requires a rapid construction of building and facilities to restore the affected areas

The labor cost has reached all-time high levels in the recent times. This increase in labor cost has led to bringing changes in the construction processes to effectively utilize the resources to extract maximum productivity at minimum additional cost

Also, there has been a shortage of skilled labor workforce that further necessitates creating workspaces that guarantee stable jobs for the skilled labors

The new technological advancements and interaction of information technology with civil engineering has led to the development of various 2D and 3D design software in the past that has helped the construction industry a lot. And, there have been more dramatic changes in the construction industry with development of software for Building Information Modelling (BIM), which are becoming a trend and more commonly used throughout the world

The health and safety concerns for the construction workers has led to making changes in the construction procedures on the field. Taking the construction process from field to a

factory setting has also gained reputation for improving health and safety of workers as it provides a comparatively safer work environment

There has also been a shift towards promoting greener and sustainable construction practices that require changing how things are done in the construction industry today

The factors listed above are getting popular day by day, and their influence on the construction industry is also increasing at a rapid rate. Prefabrication is one such method that provides a satisfactory solution to all the demands discussed above.

Construction on sites involving prefabrication begins simultaneously with the site work. For Example, as the excavation work proceeds on site, prefabrication of superstructure and can be started on an offsite location, which will significantly save construction time and allow the projects to be completed in lesser time when compared to tradition construction practices. As the work in completed inside a factory, it mitigates the risks of delays in construction schedule due to bad weather. The building and facilities constructed employing prefabrication can be sold or leased sooner as the construction is completed ahead of time that in turn leads to faster returns on investment. Prefabricated structures are built with same materials, using same codes and specifications as the traditional construction, and once fully assembled; they are virtually indistinguishable from their site-built equivalents.

As the prefabrication work is done in a factory setting, it provides an indoor construction environment for the workers to do their work. This indoor work environment reduces the risks of accidents and thus, reducing the liabilities related with them. Factory setup of construction also promotes stable jobs for the skilled workers. Here the productivity is also high as compared to traditional construction practices that help in obtaining maximum productivity from the workers

at minimum cost and thus improves project economics. Integrating BIM further adds to these advantages and makes prefabrication a worthy alternative over traditional construction methods.

Sustainability of a project is also enhanced by using prefabrication it uses factory controlled setup. Less waste is generated when building in a factory that eliminates the need for the significant quantity of waste recycling. Less material waste also means less investment in buying new materials that mean lesser inventory control. The majority of the prefabrication work is done indoors and away from the construction site, which greatly minimizes onsite traffic and onsite labor cost.

Prefabrication – Present and Future

Prefabrication is on the agendas of the government and commercial sectors in various countries across the world. A major consideration is given by Europe, Canada, United States, New Zealand and Australia. Prefabrication is considered as an important way of improving quality, safety, sustainability and value within the slow changing construction industry. The scale and demand for prefabrication is increasing day by day as it offers various merits over the traditional construction practices. The increase in construction products manufactured and produced in factories at an offsite location and brought to the site for assembly and erection is now slowing becoming a common trend as it offers better quality control, more efficient site processes, more environmentally friendly manufacturing, and an overall reduction in the project cost. The demand for prefabrication and modular construction is growing, and also is the complexity related with it. Back in the old days, you would typically see a prefabrication and modular construction being utilized in the construction of temporary housing and accommodations, but now it is being used in advanced projects to create permanent buildings and facilities ranging from single family housing

to residential apartments, and large commercial buildings. Prefabrication has allowed the construction of these buildings and facilities with cost savings and timeframes that were earlier not achievable.

The use of prefabrication/ modularization has not witnessed a steady increase over time. It has seen fluctuations in its demand throughout the history of building construction whenever there was a drastic need for speed and efficiency in times of colonialization, wars, and economic boom. However, the technological advancements that have taken place in that last two decades have led to increase in capabilities of what the prefabrication process can accomplish in the construction industry. Building Information Modelling (BIM), modern high-quality materials, and advanced manufacturing facilities these days offer substantial enhancement in the productivity on projects that was not possible earlier. Recently, a committee of experts selected by National Research Council recognized the fact that prefabrication/ modularization will play a central role in improving the efficiency, affordability and competitiveness of the U.S. construction industry in near future. With U.S. construction market facing acute shortage of onsite skilled labors, and also where the stakeholders are trying to be greener and more sustainable, a majority of them understand that this is the right time, more than ever, for extensive implementation of offsite prefabrication and modularization solutions on a major scale in the construction industry.

Prefabrication surely offers a potential alternative to traditional construction practices, but there have been many hindrances in its applications to realize its full potential. Some of the key factors that block its path are as follows:-

Higher initial construction cost and time: - It requires high initial investment as many of the companies have to start from scratch. Most of this investment will go on in hiring

professionals adept in this field and investing in software like BIM, which will make the tasks smooth. Also, there is more effort required during the project planning phases to efficiently integrate prefabrication in the project, and thus requires more initial time

Inflexibility in changes: - As most of the construction is done in an offsite facility as per initially agreed upon design drawings and specifications, and at the same time site work for excavation and foundation also continues. Now, if there is a need to make some change that arises due to site conditions during these phases, and if that component is already prefabricated then it will lead to problems

Lack of background information and lack of experience: - This is also a common problem as many of the engineers and architects do not fully understand the ways in that they can benefit from prefabrication. Haphazard efforts without prior knowledge often lead to reverse effects and causes higher cost and delays instead of being economic and fast.

Lack of demand for prefabricated structures: - Many investors are demanding economical, greener and faster solutions for their construction projects, but many of them are hesitant to employ prefabrication as a potential solution as they are uncertain of its success.

Transportation issues: - Often there may be such site conditions that will not allow transportation of large modules to and from the site that will limit the size of these modules and thus increase the number of trips required to do the same job.

There is no doubt that prefabrication and modularization methods have a lot of merits and so proper steps must be taken to educate people and spread the idea. To solve the problems stated above owners, investors, architects, engineers, contractors, etc. play a very vital role.

Owners should consider using prefabrication and modularization process in their projects. Gone are those days when prefabrication was just used for temporary establishments. With the precision

and details offered by software like BIM, flexibility offered by modern construction materials and manufacturing facilities, etc. have contributed together to make prefabrication a worthy alternative to obtaining a significant gain in the projects. Owner demand is the primary factor for architects and engineers to include prefabrication in their project designs.

Architects should understand and also educate their clients about the benefits of prefabrication. Architects are often the first people to meet a client on a new project, and also they have the greatest influence during the design phase of the project in determining whether prefabrication will be used or not. For being able to do this, architects have to understand the benefits of this method in improving project productivity, making it more sustainable and increasing the Return on Investment for the client and other stakeholders of the project. Architects should educate their clients regarding the measurable benefits offered by prefabrication:

Reduced project schedules – saving a month or more, and decrease in purchase and installation cost of materials that ultimately decreases the project cost aiding in lean construction

Increase in construction site safety that results in fewer accidents and lowers the insurance cost

Reducing the construction waste significantly, and thus making the project greener and more sustainable.

If an architect is able to convince the owner, then he should incorporate prefabrication his designs from day one. The early inclusion in design process allows for maximum advantages.

Engineers are the one who are responsible for the structural integrity and efficiency of the buildings in design and construction phases. Engineers must evaluate the quality and availability of the prefabricated products and be the catalyst in promoting its use on the projects.

General contractors and construction managers are the people responsible for bidding and constructing the projects. Thus, they must include the efficiency, green and sustainability factors offered by prefabrication in their planning and bidding processes. This will not only lower the project cost but will also make them more competitive in the market.

Manufacturers and specialty contractors are the central points in all this. If there are enough manufacturers and specialty contractors who are adept at making prefabrication components, then it will make the task of architects, engineers and contractors easy. Thus, the realization of the full potential of prefabrication depends on the efficacy of manufacturer and specialty contractors who must be encouraged to invest in this field.

Case Study

Fort Sam Houston Medical Education and Training Complex - Largest Modular Project in North America Meets Army Needs

Figure 4: Fort Sam Houston Medical Education and Training Complex in San Antonio, Texas

The U.S. Army Corps of Engineers (USACE) recently incorporated permanent modular construction (PMC) and onsite construction for its recent construction project in Fort Sam Houston. USACE project was to build a Medical Education and Training Complex in the city of San Antonio, Texas. Using PMC offered an effective solution to speed up the construction of the project without compromising the quality, safety, and durability of the building. The Army has strict requirements for its projects that aim at making each project a LEED Certified Project. The alternative of PMC helped realize the Army’s requirements and made it a LEED certified building.

With a total square footage of one million sqft, - it the world’s largest military medical training facility, and as it fused PMC into its project construction methods, it is also regarded as one of the largest permanent modular construction projects in the world. This facility will house 2400 medical trainees. As part of the Federal Government’s Base Realignment Closure program (BRAC), the dorm housing at Fort Sam Houston will signify an important stride towards modular construction. The contractor for this project was Warrior Group that combined the merits of factory built modules with traditional steel and concrete construction. This resulted in a state of the art structure built at a reasonable price tag and in relatively short span of time.

Figure 5: Erection of PMC Module

To accomplish this task, three types of construction techniques were used in the design. First was to include factory built dormitory modules that utilized a wooden shear wall design that helped in resisting the lateral loads coming on the structure. Second methods employed was the steel frame construction in the office areas that uses brace frame type of steel column and beam construction giving the building an additional advantage in resisting lateral loads. The braces are inserted in

office walls. The third approach was to utilize moment frame construction in their design that uses rigid-welded connections at the intersection of a column and beam to resist lateral loads. This provides the ability to create large open spaces for rooms without columns. This technique was useful in building conference rooms and briefing areas. The project is able to meet the government’s stringent Anti-Terrorism Force Protection Requirements that should include various features like progressive collapse, strict air infiltration criteria, etc. It also met the requirements of LEED Silver Certification standards. Thus, this project stands as a testament to the various advantages concerning quality, safety, sustainability, and superior results that are achievable by effectively utilizing prefabrication and modularization in the construction industry.

The Stack Rental Apartments, New York - Potential Solution for Much-Needed Urban Housing

Figure 6: The Stack in Inwood, Manhattan

The Stack is a multifamily housing project in located in Inwood, Manhattan. It is the first modular building in Manhattan. It is a seven-story building with 28 units. It is constructed on a relatively small site measuring 50’ x 100’. It has a total area of 38000 sqft out of that 26000sqft is the residential area. It aims at providing affordable housing. The building is designed to express that it is built using prefabrication and modularization. Each of the 3D box structure or modules was built at a factory facility in Pennsylvania and was shipped on site with the help of trailers and erected with the help of cranes. Each module was almost completely built in the factory with all the plumbing, electrical, and other fixtures installed in the monitored space of the factory. The modular construction also gave the distinct advantage of creating the unique façade of the building. The façade of the building consists of projections protruding out of the building that will not have been possible with such ease if traditional construction practices were used in for building it. The strategic step taken in this project was to develop small and left out portions of the city. These small and left out portions are surrounded by many existing structures that escalate the per square foot construction cost considerably. Prefabrication allowed the builders to get in and out of the site in less time and thereby to cause the least amount of disturbances to the neighboring areas. The excavation, foundation and first-floor slab construction of the building were done in the tradition way. It took around three months to complete. During this three month period, the construction of all the 28 modules of the building was finished in the offsite prefabrication yard in Pennsylvania.

Figure 7: Strategy to fill empty blocks

Figure 8: Prefabrication facility in Pennsylvania

Figure 9: Erection of fully completed module

The building is a combination of steel and concrete components. After finishing the first-floor slab, the modules were transported to the site and erected one my one. The modules were literally stacked on top of each other, and this is where the building gets its name “The Stack”. It took only 19 days to erect all the 28 units of the building, and then the finishing work was started that finished in the next four weeks. So overall it took roughly 5months to construct the building. If we consider the time spent in planning the project, then the total project duration was 12 months, which is considerably less than traditional method that would have taken at least 16 months to complete. From inside the building does not feel like it was not constructed in a traditional manner. It has all the amenities required in a comfortable housing unit. The damage caused to the completed modules during transportation and erection was also negligible, and was restored to pristine conditions after minor repairs. Thus, construction of The Stack also reinforces the merits of prefabrication and

modularization in the construction industry providing various advantages over the conventional methods of construction.

Conclusion

Lack of skilled labor, high cost of labor, unsteady jobs etc. are requiring urgent reforms in the way construction is handled, and also as more and more consideration is given to sustainability while keeping the project cost low, the process of prefabrication has the potential to provide a worthy solution to all these problems.

From the case studies and the literature review in the research paper, it can be clearly concluded that prefabrication has a huge prospective in improving economy and sustainability of project, and also, reducing the construction schedule.

References

1. “Prefabrication & Modularization, Increasing Productivity in the construction Industry” (2009), McGraw Hill Construction Report

2. Anders Björnfot and Ylva Sardén (2006) “PREFABRICATION: A LEAN STRATEGY FOR VALUE GENERATION IN CONSTRUCTION”

3. “Building Modular- "The Stack" Case Study” 2015, https://www.pinterest.com/pin/261208847113615119/

4. “Modular Building Institute (MBI)” http://www.modular.org/ 5. “History of Prefab Houses” http://home.howstuffworks.com/prefab-house1.htm 6. “Prefab in History” http://www.prefabaus.org.au/what-is-prefab/prefab-in-history/ 7. “OFFSITE CONSTRUCTION EXPO” (2015),

http://www.offsiteconstructionexpo.com/htmlPage.aspx?name=osce_home