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Feature - Roofing
Roofing Solutions
The roofing industry has grown by leaps and bounds in the
country. SHALINI AMARNANI reports on their importance in the
construction scene
Roofs play a key role in protecting building occupants and
interiors from outside weather conditions, primarily moisture.
The roof, insulation, and ventilation must all work together
to keep the building free of moisture. Roofs also provide
protection from the sun. In fact, if designed correctly, roof
overhangs can protect the buildings exterior walls from moisture
and sun. The concerns regarding moisture, standing water,
durability and appearance are different, reflected in the
choices of roofing materials.
Indian Roofing requirements The most typical roof system
in India is the Hydrostatic i.e. Water Barrier System designed
to resist the passage of water at joints, laps and junctures
under hydrostatic pressure. In addition, the roof system needs
the strength and capability of spanning structural members
such as circular/square/rectangular hollow sections, channels,
angles etc. acting as purlins without support of any solid
roof deck. In achieving this, the roof covering also needs
to act as a Hydrokinetic System i.e. Water Shedding System
in view of the heavy rainfall that is encountered in large
parts of the country, particularly the N-E, E, S-E, S and
S-W. The Central and Northern regions being lower rainfall
zones, do adopt slope roofs of 1:6 or less, but, in general,
slopes of 1:4 to 1: 2.5 are recommended by the Bureau of Indian
Standards based on studies and research conducted by them
under Indian conditions. In areas with snowfall, slopes as
steep as 1:2 are common, particularly for smaller spans. The
necessity was therefore felt for roofing and cladding material
that was: (a)Capable of providing Hydrostatic and Hydrokinetic
protection (b) Withstand the vagaries of atmospheric corrosion
(c)Retain aesthetics and appearance Types of Roofs A number
of roofing materials are available... Asphalt Asphalt is the
most commonly used roofing material. Asphalt products include
shingles, rollroofing, built-up roofing, and modified bitumen
membranes. Asphalt shingles are typically the most common
and economical choice for residential roofing. They come in
a variety of colours, shapes, and textures. There are four
different types: strip, laminated, interlocking, and large
individual shingles. Laminated shingles consist of more than
one layer of tabs to provide extra thickness. Interlocking
shingles are used to provide greater wind resistance. And
large individual shingles generally come in rectangular and
hexagonal shapes. Built-up roofing (or BUR) is the most popular
choice of roofing used on commercial, industrial and institutional
buildings. BUR is used on flat or low-sloped roofs and consists
of multiple layers of bitumen and ply sheets. Metal Most metal
roofing products consist of steel or aluminium, although some
consist of copper and other metals. Steel is invariably galvanized
by the application of a zinc or zinc/aluminium coating, which
greatly reduces the rate of corrosion. Metal roofing is available
as traditional seam and batten, tiles, shingles, and shakes.
Products also come in a variety of styles and colours. Metal
roofs with solid sheathing control noise from rain, hail,
and bad weather just as well as any other roofing material.
Metal roofing costs more than asphalt, but it typically lasts
2 to 3 times longer than asphalt or wood shingles. Says Kiran
Bhatt, Sales Coordinator, Colour Roof India Ltd, "Our
products are very popular since the have lasting value and
are available in attractive colours. The 'rainbow style' range
is a great alternative to".
Wood
Wood shakes offer a natural look with a lot of character.
Because of variations like colour, width, thickness, or cut
of the wood, no two shake roofs will ever be the same. Wood
offers some energy benefits, too. A wood shake roof, however,
demands proper maintenance and repair, or it will not last
as long as other products. They are unpopular in India due
to heavy rainfall.
Concrete and Tile
Concrete tiles are made of extruded concrete that is coloured.
Traditional roofing tiles are made from clay. Concrete and
clay tile roofing systems are durable, aesthetically appealing,
and low in maintenance. They also provide energy savings and
are environmentally friendly. Although material and installation
costs are higher for concrete and clay tile roofs, when evaluated
on a price versus performance basis, they may out perform
other roofing materials. Tile adorns the roofs of many historic
buildings as well as modern structures.
Single-Ply
Single-ply membranes are flexible sheets of compounded synthetic
materials that are manufactured in a factory. There are three
types of membranes: thermosets, thermoplastics, and modified
bitumens. The advantages of prefabricated sheets are the consistency
of the product quality, the versatility in their attachment
methods, and therefore, their broader applicability. They
are inherently flexible, used in a variety of attachment systems,
and compounded for long lasting durability and watertight
integrity for years of roof life.
Micro Concrete Roofing Tiles
Micro Concrete Roofing Tiles (MCR Tiles) are a low cost alternate
to roofing materials. There is a acute shortage of locally
available cheap, cost effective materials to build houses.
There has been developed many types of such materials in our
country. The conventionally available materials do not offer
acceptable solutions. Corrugated Galvanised Iron Sheets are
continuously escalating in price and are thermally uncomfortable.
All sheets have the inherent characteristics of health hazards
due to asbestos handling. Fibre clay tiles are also dearly
because of increase in fuel prices for firing purposes. Micro-concrete
roofing (MCR) technology meets the growing demand for high-quality
roofing. MCR tiles are a cost-effective and extremely versatile
material. They can be used on steel and wood under structure
to make attractive roofs on residences, farmhouses, gazebos,
highway constructions, verandahs and pavilions. In areas with
heavy rainfall like Mumbai, MCR tiles are used extensively
for cladding material offering both waterproofing and aesthetic
appeal.
Mangalore tile roof
Across most of India, Mangalore tiles have been preferred
roofing material, especially for farmhouses and hotels. "Made
of compressed mud and burnt under controlled conditions, these
tiles are uniform in thickness and pattern. They have a nostalgic
appeal, though their maintenance is an issue," says architect
Sandeep Khosla. Made of compressed mud and burnt under controlled
conditions, these tiles are uniform in thickness and pattern.
They have a nostalgic appeal, though their maintenance is
an issue. A metal sub-structure is provided these days avoiding
the use of wood, lest there be termite attack. Large companies
like Lafarge sell terracotta tiles with slots to fix them
reducing the damage cost associated with these tiles.
Green Roofs
Green roofing has also been used during the Renaissance in
Italy, as well as in Spain during the 16th and 17th centuries.
Russia, France, Mexico and India all contain evidence of green
roof structures that date back 100's of years. A green roof
can be loosely defined as a contained green space on top of
a man made structure. Modern green roofing layering techniques
though, require a more specific definition of what a modern
green roof must contain. This includes the components of the
green roof itself. The bottom layer is the building's roof
structure followed by a waterproofing membrane. A drainage
layer is then applied topped by a filter cloth to contain
the roots and soil. Subsequently, a growing medium is added
and finally the soil and plants. Green roof technologies offer
social, economic and environmental benefits for owners, builders
and the public. Long range benefits such as reduction of the
urban heat island effect and reduced air pollution will still
take years to see; but immediate annual results in energy
cost reduction, insulation, and improved aesthetics are instantaneous
and will hopefully be enough to propel this new industry to
take hold and grow in India.
Clay concrete roof planks The use of clay based tiles and
roofing shingles is a common practice in the present building
industry. Clay concrete roof plank is a low cost, maintenance
free roofing material. The product is based on jointing burnt
clay tiles or channels with concrete and steel reinforcement.
The tiles and channels are made of common clay with admixtures
of industrial wastes. "Burnt tiles are arranged in a
mould along with nominal steel reinforcement and joined with
concrete. The entire roof is then covered with a monolithic
screed concrete," says architect Rahul Gore . Filler-slab
It is an eco-friendly roof. Architects such as Jaisim of Bangalore
and Gerard D'cunha of Goa use it in some of the structures
designed by them. The idea is to save a lot of concrete in
the making of a roof. This is achieved by putting a layer
of clay block, fly-ash block or hollow concrete block or even
Mangalore tiles, arranged side by side with reinforcement
between them. Concrete is poured over this layer. About 30
to 40 per cent less concrete is used. When ready, you would
see the tiles from inside the house and the concrete roof
from outside. This roof is heat-resistant. Corrugated roofs
Options considered for commercial buildings include Galvanised
Iron Sheet, Galvanised Aluminum Sheet, Aluminum Sheet, PVC
Sheets, Plastic Transparent Sheets and Mud-reinforced Plastic
Sheets. Most of them could be used for backyard roofing, over
the structures that are not used on regular basis or where
very secure strong roof is not needed. Plastic sheets lose
shape when exposed to heat. PVC sheets fade over time. Mudreinforced
plastic sheets become brittle and crack on impact. Most of
these thin sheets radiate heat.
Newtech Prefab. is a leading insulated roofing and cladding
company that manufactures insulated panels for wall cladding
and roofing sheets with two side sheet and insulation material
like PUF, Glass Wool, and Rock Mineral Wool in between to
maintain better temperature, high strength, unique for cold
rooms and sound insulation. Also adept at Pre-Engineered Steel
Buildings involving Design, Fabrication, Erection, Erection
and installation of Metal Building Systems, the products custom
made, easy, fast to erect and can withstand severe climatic
conditions. Turnkey projects for building for Industrial,
Commercial, Institutional, Retail, Aircraft Hanger, Shopping
Centers, Warehousing, and Offices etc. are also undertaken.
The company has the expertise in Trapezoidal Roofing &
Cladding in Galvanized, Galvalume Bare & Precoated steel
sheets. It manufactures Roof & Floor Deck Panels and Clip
fix Roofing System too that is leak proof. Metallic False
Ceiling Systems manufactured by us are in vogue. Metal Crash
Barrier are manufactured out of structural grade steel to
provide safety on highway as well as act as a guideline to
drivers in rainy & foggy conditions and also during night
driving.
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