Feature – PEB
Pre-engineered to Last
Pre-engineered buildings made of prefabricated components,
which offer a host of advantages, are making inroads in the
construction industry. CHARU BAHRI discovers how this building
concept stacks up against the competition.
A s a concept, customisation is seen as diametrically opposed
to the readymade. But the two are seamlessly reconciled in
the construction industry in the form of pre-engineered buildings
(PEBs) made of prefabricated components. Computer-aided designed
pre-engineered buildings featuring a structural steel framework
of primary and secondary members to which factory-finished
cladding and roofing components available in knock-down condition
are attached, have slowly made inroads in the construction
“Warehouses of varied descriptions and functionalities
required at seaports, airports, in the supply and distribution
channel network for bulk commodities and as part of cold chain
infrastructure for perishables for export and retail businesses
are increasingly being constructed as pre-engineered buildings
made up of prefabricated components,” notes N Srinivas,
Director - Technical, Lloyd Insulations (India) Ltd.
The almost unlimited possibilities for customisation inherent
in this mode of construction easily take care of the differing
storage configurations required by different commodities.
For example, some products may require stacker reclaimers
to be mounted on the building structure, while cold chain
facilities would require insulated temperature controlled
enclosure to be accommodated within. PEBs with pre-fabricated
insulated or un-insulated external panels are precisely what
are most appropriate for these needs.
The benefits are not limited to customisation making use of
readily available components (See Box 2 for more advantages).
Strategically well planned facilities with optimised engineering
also offer the twin advantages of overall economy (both in
first cost as well as in maintenance, See Box 1) over their
service life as well as speed of construction, a major requisite
for any time-bound infrastructural project. In fact, the interest
savings that ensue from a faster start-to-finish construction
time could go a long way in enhancing commercial, industrial
and institutional interest in the multi-storied versions of
these structures, even in times of economic slowdown.
Manav Goel, Vice-President - Marketing, Minaean Habitat (India)
Pvt Ltd, is quick to point out that these structures have
less of an environmental impact. “Prefabricated pre-engineered
building systems are more stable amid temperature fluctuations,”
he says. “When optimally designed using light gauge
steel and appropriate cladding material, these better withstand
a temperature fluctuation from - 6o C to + 80o C. Traditional
concrete constructions may develop cracks in extreme temperature,
whereas suitable cladding material used as building components
in these structures are a lot more stable. Moreover, the dry
construction technology used to construct these structures
may be taken up in any weather condition and is also eco-friendly
as it completely does away with the cement and water slurry
waste that seeps into and contaminates underground water supplies.
Arguably though, the absence of standards applicable to the
prefabricated components industry is impeding its growth.
“After all,” says Srinivas, “any built structure
must deliver not only the functional needs of the end user,
but also assure the highest levels of safety against all loads
and exposure conditions that are expected to be imposed during
construction as well as service phases of a building. Today,
our accent is on green buildings, with energy efficiency and
resource optimisation built in to each project.”
Lack of a dedicated PEB code plays spoilsport?
PEB design concepts incorporate all these vital factors and
buildings built with prefabricated components have the potential
to overhaul the more traditional ‘iron truss’
and ‘brick and mortar’ approach to design and
construction owing to their inherent strengths of speed and
economy. However, this evolution is largely depen-dent on
the creation of a dedicated building code dedicated to these
“PEBs are currently based on Indian codes for earthquake
forces and local wind forces,” explains Manish Garg,
President, Everest Steel Building Solutions, Everest Industries
Ltd. “Thereafter, customers have the choice of either
following the AISC (American Institute of Steel Construction)
or the IS code for the analysis of structures, as the IS 800
release 2007 is quite similar to the AISC code. So following
either results in extremely safe and sound buildings as long
as the manufacturer uses appropriate software tools to ensure
that steel is used at the right places, which Everest is capable
of doing using the customised software at its disposal. Steel
buildings use ductile detailing that makes these buildings
extremely safe during earthquake attacks.”
Even so, the Indian PEB industry would welcome a detailed
code, as it would enhance the overall image of PEBs. “At
present,” says Goel, “the absence of a building
code laying down specifications for pre-engineered building
systems created with light gauge steel prefabricated components
forces us to follow American and British standards. Indian
standards would boost consumer confidence in the industry
as well as offer its players much-needed benchmarks.”
Given that PEB as a concept finds its strength in its innovative
design process, which in turn derives its strength from the
optimal deployment of metal to exactly match the loads that
are incident on that element, Srinivas emphasises the need
to optimise our mindset as well! Once comprehensive standards
are in place, the scope of pre-engineered and prefabricated
buildings would also widen, to include sports facilities offering
an unobstructed view to spectators, creation of wide network
of primary and secondary health centres, schools boasting
an optimised layout of classrooms and facilities, and mass
housing for rehabilitation of slum dwellers. These socially
relevant development areas must attract highest priority while
governments plan the rejuvenation of our economy.
Would standards stifle innovation?
In spite of the overwhelming endorsement of the need to standardise
PEB systems, Dr M Pradyumna, Director - Design & Development,
Geodesic Techniques Pvt Ltd, says that any building code would
probably not do justice to all the various combinations of
RC-based prefabricated components that would be required to
implement these designs. As these components are generally
designed for a specific purpose to resist a specific
set of forces, standardisation is best attempted in individual
projects that are sufficiently large. However, standardi-sation
is mandated in the manufacture of steel-based components made
by indivi-dual manufacturers, a typical case being that of
space frames. Each manufacturer has an internal set of standard
compon-ents that are reused in practically every project.
In this example, if a code were specified, it would take away
the freedom that exists today in the marketplace to develop
newer and better designed components.
Innovations in the PEB realm
Rapid advancements in the compo-nents available to construct
these structures are ensuring a lot more than functional efficiency
to end-users. For instance, innovative concepts like hidden
fasteners and the wide array of colours in which these are
available offer architects an exciting set of aesthetic options.
Occupants also benefit from a favourable inner ambience, thanks
to the use of sandwich panels that offer high-efficiency thermal
insulation, excellent noise transmission rating and good internal
noise absorption. In this category, PUF as a material is fast
catching up as it offers better insulation, is lightweight
and has a considerably long life.
Speaking of the ease and economy of ambience control in pre-engineered
buildings, HG Chandrashekhar, Vice President - Building Solutions,
Tata BlueScope Steel Ltd (a member of Indian Green Building
Council, Hyderabad, which works on LEED rating system for
Green Building Certification), explains that BUTLERTM Building
Systems come with several green building features that help
reduce the load on air-conditioning. “Fibreglass insulation
material in the roof system is coupled with the excellent
thermal reflectivity property of ZINCALUME® used as roofing
material. This helps reduce the impact of outdoor temperature
variations, thus consequently reducing the load on air-conditioning.
Wind-driven turbo vents and ridge vents ensure natural ventilation.
Moreover, a specially designed water and sand-resistant industrial
louvre system ensures free inflow of air.” In April
2009, the Building Solutions (BS) division of Tata BlueScope
Steel received the prestigious Factory Mutual Approval (FM
Approval) for its MR-24® standing seam roof system and
BR-II™ roof panel lap seam roof system, both roofing
systems of BUTLER Building Systems. This approval from FM
Approvals, an independent, third-party testing laboratory
that certifies products and services that meet the highest
property loss prevention standards, certifies the high product
quality and reliability of these roof systems, and thereby
qualifies the company to provide world-class PEB solutions
to all FM Global insured clients inves-ting in India and the
As long as the industry lays stress upon innovation and works
towards ensuring that its new solutions meet the most rigorous
standards of the industry, this innovative construction technique
is bound to find more takers over time.
Computer-aided designed pre-engineered buildings have slowly
made inroads in the construction industry.
PEBs have the potential to overhaul the more traditional ‘iron
truss’ and ‘brick and mortar’ approach to
design and construction owing to their inherent strengths
of speed and economy.
Rapid advancements in the components of PEBs are ensuring
a lot more than functional efficiency to end-users.
PUF as a material is fast catching up as it offers better
insulation, is lightweight and has a considerably long life.
Prefabricated pre-engineered buildings offer significant advantages
over conventional structures. We list a few:
• Lightweight: Steel structures offer a
higher strength-to-weight ratio vis-à-vis conventional
RCC beam slab or plane truss and purlin configuration.
• Stable configuration: Steel structures can be designed
to be far more stable than conventional structures.
• Speed of construction: Steel-based structures are
constructed far more rapidly than conventional systems. This
into a saving of interest and increases operational revenues.
• Column-free space: Framed structures provide larger
column-free spaces ideal
for machine shop floor or storage applications where freedom
of materials movement
• Flexibility: These structures may be easily dismantled
and relocated or extended without damaging the structural
integrity of the frame.
• Integrated services: The framework of these structures
functions as a natural deck for building services like HVAC
or to fix a false ceiling without burdening the structure
with an additional supportive framework.
• Accuracy: Components prefabricated in machines are
far more accurate and relatively smaller than the components
used in conventional construction which makes them easier
to handle and transport.
• Fire and blast-resistance: Double-layer grids are
more fire-resistant than conventional structures and better
resist aerial or terrorist attacks and explosions.
• Versatile: These structures can be clad with a wide
range of materials such as aluminium, steel, asbestos cement
sheet, glass, polycarbonate sheet and pre-cast concrete.
• Economy: This method makes for cheaper buildings of
larger spans and/or heavy loads.
Tax Structure Reform Boosts Prefabrication
Prefabricated components are an essential part of pre-engineered
buil-dings.Given thourgh these components offer intangible
benefits like better quality of end products, safer and better
working environment, improved reliability of delivery and
speed of construction, Dr M Pradyumna, Director - Design &
Development, Geodesic Techniques Pvt Ltd, points out that
“earlier, the excise duty levied on factory-made goods
ensured that investors did not see this style of construction
as a viable proposition. Now, the levying of service tax on
site fabrication and the recent reduction in excise duty on
factory-made components has made prefabricated components
a financially viable option.”
Standards and Codes: What has been done? What remains? N
Srinivas, Director - Technical, Lloyd Insulations (India)
Ltd, shares some pointers
• Steel design: The revision in the Code of Practice
for structural steel design (IS:800-2007) is substantially
in line with this building concept. But new standardisation
work is needed to cover materials such as composites (like
sandwich panels), and codes for fire safety.
• Fire safety: In the absence of good fire safety codes,
panels with highly combustible inner cores like foam polystyrene
are being propagated and used owing to their low cost when
highly researched fire safe panels incorporating polyisocyanurate
and mineral wool cores with excellent fire rating are widely
• Panel facings: Today’s PEB structures incorporate
panels with steel facings with proven advanced metallurgical
protection like aluminium plus zinc coatings. While standards
exist for galvanised steel, we need a National Standard for
advanced metal protection systems. Metal exterior surfaces
must be engineered precisely to meet the aggressiveness of
the diverse climatic and environmental conditions where they
have to perform. Exterior finishes like organic coating (paint
systems) also need to be covered by National Standards specific
to these colour-coated products.
• Components: A large number of components like windows,
doors, louvres, ventilators, awnings, canopies and loading
bays need to be standardised with respect to dimensions, functional
features, etc. Standards must integrate functional requirements
with manufacturing parameters for building components.
Why do pre-engineered buildings have a lower life cycle cost
vis-à-vis conventional steel buildings?
Conventional steel buildings use primary steel members selected
from standard hot rolled I or H Sections owing to which the
structure is much heavier than required by design. Primary
steel members have constant cross-sections regardless of the
varying magnitude of internal stresses along the length of
the member. Also, owing to the unavailability of the required
standard hot-rolled sections for a particular load, consultants
are compelled to select a higher standard section, which leads
to uneconomical and heavy designs. In a pre-engineered building,
typically, primary framing members are tapered, i.e. of varying
depth built-up sections with smaller depths in areas of lower
Traditionally, conventional buildings also use cement roofing
sheets and a plastered brick wall. Roofing requires replacement
every 10 years and brickwork requires repainting and repair
every three years. In PEBs, the roof is high-grade galvalume
and the walls are made up of permanently colour-coated metal
wall. These roofs and walls require no repainting or maintenance
over at least 25 years. Therefore, PEBs are actually zero-
maintenance structures. Over a lifecycle analysis of just
five years, PEBs prove to be at least 20 per cent more economical
than conventional buildings.