1.
Galvanized Iron Sheet

2.
Introduction
• Generally corrugated galvanized iron sheets are
extensively adopted as a covering for roofs and
sides of industrial sheds and buildings.
• They`` are commonly available in dimensions of
8 feet by 4 feet.
• Due to being cheap and easy to maintain these
sheets are preferred in instances frugal and
relatively aesthetic form of roof.

3.
Characteristics of zinc coating
• It retains the sheet's full initial strength.
• It provides a more pleasing appearance to the
sheet.
• It increases the life of any suitable organic
finishing system applied over it.

4.
Design
• G.I. sheets are available in 2 basic forms- flat
and corrugated.
• Corrugated sheets are further classified as
trapezoidal or wavy sheets.

5.
Advantages
• Relatively cheap- The actual sheet costs less than its
alternatives like aluminium or steel. The sheets are
also virtually maintenance free with higher
longevity.
• Reliability- Galvanized coating is a proven method
of increasing the sheet’s defense against corrosion.
• Simple logistics- Due to its unique metallurgical
structure, galvanized sheet offer high resistance to
mechanical damage occurring during transport,
erection and service.
• Ease of inspection
• Aesthetically pleasing

6.
Disadvantages
• These sheets are prone to leakge and rusting
earlier than their counterparts.
• Construction of a storey above this roofing is not
possible.
• Weather tends to have adverse effects on the
longevity of these sheets.

7.
Manufacturing
• Hot dip galvanizing- This process consists of
immersion of the sheet in molten zinc. The zinc
used is high grade with a content of minimum
99.95%
• The sheet is pretreated for degreasing, pickling,
cleansing, and then sent through the annealing
furnace and a pot containing molten zinc.

8.
• Electro-galvanizing- this process consists of
immersion of sheet in an electrolyte, a solution
of zinc sulfate or cyanide.
• Electrolytic action deposits a coating of pure zinc
on the surface of the sheet.
• Through this process the thickness of the coat
can be accurately controlled.

9.
Technical Specifications
• Estimated life span of zinc coat:-
Zinc coating
weight
Rural Tropical Suburban Urban Highly
industrial
600 40 40 30 25 15
375 30 30 20 17 9
300 20 20 12 10 7
180 8 8 5 4 3
100 6 6 4 3 2

10.
Raw material
• Galvanized iron sheets.
• J- hooks
• Bolts and nuts
• Bitumen washers
• Frame/purlins
• Valley gutters

11.
Installation
• The sheets are laid on purlins with the line of
corrugation parallel to side of area to be covered. Its
corrugation exists parallel to the length of area to be
covered to ensure maximum strength.
• Each sheet is fixed by means of a J-hook not less
than 8mm. The hooks sre fitted with bitumen
washers and nuts to ensure a snug fit.
• The holes are in the ridge of corrugation instead of
the valley. Holes for hooks are drilled, not punched.
• The sheets are laid with a lapping of 15 mm.
• A valley gutter is fixed wherever required.

12.
Cost and pricing
Gauge
(Area= 8’*4’)
Thickness
(in mm)
Weight Total Price
(Rate=Rs
52/kg)
22 0.853 18 936
20 1.006 21 1092
18 1.311 26 1352
16 1.613 38 1976
14 1.994 50 2600