Bajrang Steel (Sales) Corporation. SRCB Road, Fancy Bazar, Guwahati-781 001
Overtheyears, TATA Steel has altered the landscape of the roofing industry in India. The company has been a pioneer in the field of manufacturing superior quality TATA Shaktee Galvanised Corrugated (GC) sheets.
Manufactured with world-class technological expertise, these GC sheets are stronger and longer lasting than any other ordinary GC sheets. TATA Shaktee GC Sheets are not only made of virgin steel processed at TA-TA Steel's state-of-the-art Cold Rolling Mill but also have uniform Zinc coating on them, which gives them the re-quired strength in fighting the weather and to last longest.

Living up to the company's assurance of good quality and trustworthy products, these sheets are manufact-ured to exact parameters of thickness, length, width and Zinc coating as per the specified requirernents. In addition to this, TATA Shaktee GC sheets are ISI certified under Bureau of Indian Standards (BIS).

All in all, TATA Shaktee GC sheets give more value for money and are the best choice for anyone looking for a product that will perform year after year.

This manual has been created in order to make consumers aware of the best engineering practices involved
in installation and maintenance of Galvanised Corrugated Steel sheets used in Roof and Wall Cladding app-lications. We have attempted to collate best practices recommended by various Indian and global standards alongwith those received from practising shed fabricators and architects.

Please feel free to send your suggestions/feedback for improvements on this manual, if any, to Brand Mana-ger - Tata Shaktee, Tata Centre, 43 Jawaharlal Nehru Road, Kolkata 700 071
 

While one of the most important roles of roofing is to fight the weather, they also have significant effec the aesth-etic, cost and durability of a building. In Roof Cladding, factors such as rainfall, wind speed, h of building and walk-ing weight on roofs (arising out of maintenance) have considerable effect on desi roof slope, supporting structures and spacing between Purlins (Figure-1).

Design parameters for Wall Cladding is simple and str-aightforward compared to Roof Cladding. The main con-sideration in the design is spacing between the suppor-ts, known as "Side Girt" (equivalent of Purlins used in Roof Cladding). Wind speed and thickness of sheets play major role in arriving at the spacing between Side Girt.

I SLOPE

 

Slope is a major component of roof design. In absence of adequate roof slope, there is danger of accumulation, wh-ich can lead to leakage and reduced sheet life. Most commonly used roof slopes in Indii in 4 (14°) and 1 in 3 (18°) (Figure 2 & 3). However, various other slopes can be used depending upon the in1 of rainfall and wind force. In case of sinusoidal profiles, it is recommended that one should not go below sl 1 in 12 (5°). It is importantto use sealants at the end lap of sheets in case roof slope is below 5°.

 

Note: Roof slopes with 1 in 3 and higher are pi in locations with high rainfall/snowfall

I OVERHANG

 

Overhang in Roof Cladding is important from the angle of complete weather-proofing of the building "End Overhang" maintained at the "Eave End" (Gutter end) of the roof facilitates proper drainage 01 without drenching the inside of building from its front, the "Side Overhang" makes sure the rain water dl enter the building from sides (Figure-4). Overhangs are recommended below as per good engineering practice.

 

Usage of recommended accessories leads to enhanced life of Roofs and Walls. Poor and substandard quality of accessories may adversely affect the superior quality of cladding sheets leading to reduced Accessories an-d the cladding material should have similar life expectancies as that of the main structure i hence criteria for selecting the accessories such as Fasteners, Gutters and Flashings must be based on design life of the structure.

I FASTENERS  

Researches executed on causes of steel building failures worldwide indicate that almost 80% of failures start from the fasteners. Since fasteners, used on cladding and structure together, constitute roughly 6-8% of the entire project cost, several builders have the tendency to neglect this vital aspect of their project.

Fasteners us-ed on steel Roof and Wall Cladding must be of good quality and properly galvanized conformi, to 15:730 standards. This will go a long way in providing a weather proof and long lasting roof. Differe components of good quality fastener is depicted below in Figure-8.

There are various kind of hooks and screws available in the market depending upon the material and type purl-ins on which sheets need to be fixed (Figure-9). G.!. Hook Bolt should be used for fixing sheets to ang Iron pu-rlins. G.!. Crank Bolt should be used for fixing sheets to channels or rectangular/square tubes purlin G.!. Coa-ch screw (square head) should be used for fixing sheets to wooden purlins only.

The rubber washer should be 25 mm in diameter and 3 mm thick with 6 mm bore to suit 8 mm diameter bolts. This bond between rubber washer and bolt ensures water proof sealing.
The G.!. flat washer is 25 mm in diameter (if it is a round washer) and 1.60 mm thick with central hole to suit 8 mm diameter fixing bolt or screw.

The sheets are fastened to purlins (in case of Roof Cladding) or side girts (in case of Wall Cladding) by mini-um 8 mm diameter hook bolts at a maximum pitch of 375 mm.

 
   
   

 
TATA SHAKTEE GC SHEET
ORDINARY GC SHEET
RIGHT HARDNESS FOR ROOFING

Accurate tempering in TAT-A Shaktee GC Sheets res-ist cr-acks and fissures dur-ing dril-ling.

Uneven tempering causes or-dinary sheets to crack during drilling.

I HIGH TENSILE STRENGTH

High tensile strength (app-rox 700 mpa) of TATA Sha-ktee GC Sheets resist na-tural forces like hail-storms and other external forces.

Low tensile strength of ord-inary sheets results in dam-age/rupture caused by hail-torms and other external for-ces.

 

I EXCELLENT ZINC ADHERENCE

Superior technology and pr-ocess control ensures pro-per surface cleaning before coating. This means a clea-ner st-eel surface that resu-lts in ex-cellent Zinc adhe-ence.
Inferior technology and pro-cess control results in unc-lean steel surface leading to low adher-ence of Zinc coa-ting. This causes the galvan-ised surface to peel off resu-lting in reduced sheet life.
I UNIFORM ZINCOATING
Uniform 120 gsm Zinc coat-ing ensured by the sophis-ticated FEED FOR-WARD X-RAY COATING GAUGE results in even surface prot-ection.

Non-uniform Zinc coating ca-use parts of galvanised surf-ace with low Zinc coating to corrode faster. This reduces the sheet life drastically.

I ASSURED THICKNESS AND ZINC COATING
Each sheet has its thickn-ess and Zinc coat-ing prin-ted on it to ensure that the custom-ers get what they have paid for.

Thickness of the sheet and the Zinc coating applied to it is not mentioned and even if it is, it is generally incorr-ect.As a result, customers are often cheated during pur-chase.

I PERFECT OVERLAPPING

Uneven corrugations and ed-ge waviness lead to ga-ps in overlapping, resulting in a badly fabric-ated roof. Unwanted particles and moisture stu-ck between the sheet ov-erlappings re-sults in corro-sion starting from the joint.

Uneven corrugations and ed-ge waviness lead to gaps in overlapping, resulting in a badly fabric-ated roof. Unw-anted particles and moisture stu-ck between the sheet ov-erlappings results in corro-sion starting from the joint.