Angela Noah
4/5/13
WRIT 340
Professor Townsend
From Cottage to High-rise: Prefabricated Building Components
Abstract:
Though the concept of the prefabricated building has existed since the 1830’s, new technology is
allowing complex building components to be prefabricated. Now, with the promise of increasing
productivity and decreasing construction waste, many contractors are giving modular building
techniques a try.
Bio:
Angela Noah is a current junior in pursuit of a Bachelor’s of Science in Civil Engineering and a
Master’s of Science in Construction Management. She is very involved on campus in USCCMAA (a student branch of the Construction Management Association of America) and hopes to
enter the construction industry post-graduation.
Blurb:
An increasing number of buildings are being built at offsite locations. Find out how
prefabricated buildings and building components are revolutionizing the construction industry.
Animation Idea:
This animation would show how a prefabricated unit, wheter it be a whole room, a bathroom, or
an MEP rack, is created in a factor and then installed onsite. The video would start by showing
how the unit is assembled in the factory. Then the unit would be shipped to the jobsite where you
would see it being installed in the building.
Introduction
In the 1830’s H. Manning decided to send his son, who was immigrating to Australia, off
with a very special parting gift. Like any logical person would do, Manning decided to send his
offspring away with a house. One that could be built in one location, disassembled into large
pieces, packed into a hull of a ship, and re-assembled upon arrival at its final destination. From
this concept, the idea of the prefabricated house was born [9].
Today, in addition to fully prefabricated, single family homes, commercial and high-rise
buildings, full of prefabricated modules and components, saturate the market. Prefabrication has
the potential to increase on-site productive during a construction project. Because, as the cliché
Noah 2
goes, time is money, spending less time on site has the potential to positively impact a project’s
bottom line. Through the use of technology, parties involved in the construction processes are
pioneering and perfecting prefabricated and modular construction methods.
What is it?
Buildings are complex structures in which many systems come together to make a sturdy
comfortable shelter. At a very basic level, they are made from a structural support system that
contains walls that house complex electrical and ventilation systems. It is those systems and
even full rooms that have the potential to be made in a controlled factory floor separate from the
construction site.
There is a difference between modular and prefabricated construction. Modular buildings
can be broken apart in such a way that full 3-D rooms can be created as separate parts and pieced
tighter to create a functional building (Fig. 1) [12]. Prefabrication on the other hand, is merely
the off-site creation of building components that can be brought to site and assembled.
Prefabrication and Modularization: Why Now?
Noah 3
Technological Advances
The proliferation of Building Information Modeling (BIM) technology allows
prefabrication to be used in areas it has never been used before. It allows users to virtually create
a building to ensure that none of the building components intersect, or clash with, each other.
McGraw-Hill Construction found that 78% of the parties using prefab and modular construction
methods use BIM [2]. Digital coordination allows a contractor and its subcontractors to
understand how prefabricated components must be laid out and constructed to that they can
easily be tied into the building’s skeleton. The intimate understanding of how a building’s
systems fit together, allows the building to be broken up into basic building blocks.
One of the most important yet complicated systems in a commercial building are its
mechanical, electrical, and plumbing systems (MEP systems). Made up of various segments of
pipes, ductwork, and conduit, these systems snake through the walls and ceiling of a given
building (Figure 2).
These systems are very
complex, so contractors
and subcontractors who
choose to build
components of MEP
systems in a controlled
factory setting can
often create them
quicker and more
Figure 2: What may be hiding behind above the ceiling in a conference room
efficiently than could be done on site.
Noah 4
Schedule and Cost Impact
There has always been a huge emphasis on productivity in the construction industry because,
even if no work is happening on a construction site, money is being spent on the basic nonmaterial items a contractor needs for construction or general conditions (GC’s). Because GC’s
must be paid for throughout the project, the contractors are incentivized shorten project’s
schedules. In a national survey of 809 industry professionals, of 66% firms using prefabrication
and modular methods, 35% of them were able to decrease their project’s schedule by four or
more weeks [2]. So, in order to truncate a project’s schedule, a general contractor may decide to
prefabricate key items.
Construction is a semi-linear process in which certain building components must be created
and installed before others can be brought it. Figure 3 [4] shows the main tasks involved in a
Modular Construction Schedule
Project Design and
Development
Permits and
Approvals
Site clearing,
grading, and
foundations
Installation of Building
components
Site Work and
Commissioning Time savings
Offsite Building Construction
Traditional Schedule
Project Design and
Development
Permits and
Approvals
Site clearing,
grading, and
foundations
Building Construction
Site Work and
Commissioning
Figure 3: Modular construction schedule vs. site build construction schedule
construction project. With the modular construction schedule, construction on components of the
building can begin offsite while the site is prepared and foundations are poured. Being able to
Noah 5
start building construction while building components are assembles off site, allows the schedule
to be shortened as special pieces of a project are completed in a factory setting.
Where are these methods being used?
Though it is possible to create fully prefabricated modular building units, it is more common
to see manufactured build components. General
contractors such as Skanska and Hathaway
Dinwiddie, are taking advantage of the ability to
prefabricate complicated bathroom and MEP racks
(Figure 4) to shorten their schedule and
productivity.
Many mixed-use, healthcare, hospital and
hospitality projects are often made up of many
Figure 4: Factory Assembly of Prefabricated MEP Racks [3]
identical units. Because of this, some of the projects that fall into this category are using fully
prefabricated bathroom units. These bathrooms, like all prefabricated components are created in
a factory and shipped to the building site. In this type of setting, sheetrock walls and other
components can be created with machines, ensuring greater precision in the building process and
a reduction in human error. Bathroom pods are completely built, furnished, inspected, and
delivered to the project site. Onsite, they are moved into position and tied into the building’s
utilities [5].
Completed in November 2010, one of the biggest hospital prefabrication efforts to date
manifested itself in the Miami Valley Hospital Southeast Addition. Skanska Shook, a joint
Noah 6
venture between Skanska and Shook Construction, acted on the general contractor on this
484,000 square foot hospital in Dayton, Ohio, and was the party that suggested using this
construction method on the project. After getting the green light from the project’s owner,
Skanska Shook used prefabrication to help put together its 178 patient rooms and 120 overhead
MEP utitlity racks that comprised the project [3]. The identical structure of the patient rooms and
corridors, made this project well suited for prefabrication.
For this project, being able to
start building the complicated MEP
systems for the hospital before the
decks for the various floors were
poured saved a massive amount of
time [6]. Typically construction on
the corridors of a given project can
only begin after the walls and roof of
a project are completed. However,
this hospital job, construction on the
five containing prefabricated units
Figure 5: Real Schedule Impact of Prefabricated Building
Components is Shown in Yellow [3]
began before those floors physically
existed [3] (Figure 5). So, when the steel was erected and the concrete was poured for those
floors that the prefab units could be hoisted into the building and construction could begin on the
rest of those floors.
Why Isn’t It Everywhere?
Noah 7
Constructing a building with a fully modular system requires, not only technical expertise
from a given contractor, but it also requires the build to be designed in a way that allows for
construction of individual pods. There are only a limited number of architects who are willing to
subject their artistic expressions to a conglomeration of shoe boxes that can be arranged to make
a structure [10].
In addition to layout limitations, there are also physical restrictions on how big a given
module can be. Modals must not only conform to the Department of Transportation’s guideline
that limit the size of cargo a flatbed truck can carry, but modules also must be light enough to be
hoisted into place a jobsite. Because of these size restrictions, architects designing fully modular
systems would constantly need to consider the bulkiness of the materials they specify.
Limitations of prefabricated building components may be restricted by some local
building codes. The Los Angeles Municipal Code, for example, requires certain prefabrication
building components to be reviewed by a testing agency to examine how items perform from an
engineer standpoint [12]. This process doesn’t typically take less than 8 week and it can be
costly.
Though prefabrication building components are becoming increasingly more common,
costs associated with the rental of warehouse facilities for a prefabrication effort can become
costly. Also, the hoisting required for a large modular construction project may add costs that
the increase of productivity helped to reduce. Until, fully modular prefabrication in the US
become more mainstream and buildings allow for it, do not expect to see a huge increase in
massive modular construction projects any time soon.
Noah 8
References
[1] R. Kaysen. “SQUARE FEET: Squeezing Costs, Builders Take New Look at Prefab.” The
New York Times, Jun. 15,2011. [Online], Available: nytimes.com. [Accessed: Feb. 24, 2013].
[2] McGraw-Hill Construction. “Prefabrication and Modularization: Increase Productivity in the
Construction Industry,” McGraw-Hill Construction. [Online]. Available: construction.com.
[Accessed: Feb. 24, 2013].
[3] N. M. Post. “Racking Up Big Points for Prefab.” ENR.com, Sep. 8, 2010. [Online].
Available: http://enr.construction.com/buildings/construction_methods/2010/0908prefabpotential-1.asp. [Accessed Feb. 24, 2013].
[4] Modular Building Institute. “Why Build Modular?.” Modular Building Institute. [Online].
Available: http://www.modular.org/HtmlPage.aspx?name=why_modular. [Accessed Feb. 24,
2013].
[5] EggrockModular. “Manufacturing & Installing Eggrock’s Factory-Built Bathrooms.”
YouTube.com. [Online] Available: http://www.youtube.com/watch?v=jlct4U_ImkE. [Accessed
Feb. 24, 2013].
[6] cmhopper. “Skanska_Multitrade Prefabrication_ Miami Valley Hospital.” YouTube.com,
May 29,2012. [Online] Available: http://www.youtube.com/watch?v=rEgjRUsB8jM. [Accessed
Feb. 24, 2013].
[7] C. V. Bagli. “At Atlantic Yards, Ready to Test Plans for Prefab Tower.” The New York
Times, Nov. 27, 2012. [Online] Available:
http://www.nytimes.com/2012/11/28/nyregion/groundbreaking-soon-at-atlantic-yards-onprefabricated-tower.html?pagewanted=1&_r=0. [Accessed Feb 25, 2013].
[8] R. Maloney. “Modular High-Rise Breaks Ground in Brooklyn.” Arup.com, Dec. 21, 2012.
[Online] Available:
http://www.arup.com/Home/News/2012_12_December/21_Dec_Modular_highrise_at_Atlantic_
Yards_breaks_ground.aspx. [Accessed Feb 26, 2013].
[9] J. Zarroli. “Prefab: From Utilitarian Home to Design Icon.” NPR.org, Sept. 15, 2008.
[Online] Available: http://www.npr.org/templates/story/story.php?storyId=94119708. [Accessed
Feb. 25, 2013].
[10] V. Cowles, IV. Interview, Topic: “The use of prefabrication in construction.” Civil and
Environmental Engineering Department, University of Southern California, CA, Apr. 3, 2013.
[11] Modular Building Institute. “Permanent Modular Construction 2012 Annual Report.”
Modular Building Institute. [Online]. Available: http://www.modular.org/documents/2012-PMCAnnual-Report.pdf. [Accessed Apr. 3, 2013].
[12] The City of Los Angeles. “Official City of Los Angeles Municipal Code.” The City of Los
Angles. [Online]. Available:
http://www.amlegal.com/nxt/gateway.dll/?f=templates&fn=default.htm. [Accessed Apr. 3, 2013]