Technical Information
Roofing & Wall Cladding
Corrugated Iron
Corrugated Iron is still the practical, good looking roof and wall material. Now Corrugated Iron is made from light gauge high tensile steel and is light and strong and able to span longer distances. It is manufactured locally by continuously roll-forming prefinished steel coil giving an economic and high quality product.
ADVANTAGES
COST SAVINGS
Corrugated Iron being light and strong is easy to handle and can be fixed quickly and easily. Fixing is by the simple pierce fixing method using a minimum of fasteners, thus keeping building costs low.
PROTECTION
Zincalume® and Pre-painted Zincalume® coated steel provides the best protection from the environment and gives long life to any building.
LONG SPANS
Corrugated Iron is made from high tensile steel and has closely spaced ribs which have been engineered to give high strength. This allows wide support spacings while still being able to resist wind and other loads.
COVERAGE
Corrugated Iron has an effective coverage of 762mm when laps of 1.5 ribs are used.
ROOF PITCH
Corrugated Iron is designed so that the sheets overlap by a minimum of 1.5 ribs, which prevents the entry of water. The minimum recommended roof pitch is 5 degrees.
LENGTHS
Corrugated Iron can be cut in the factory to any length specified by the customer. When determining lengths required for roofs allow 50mm extra for overhang into gutters.
SUPPORT RECOMMENDATIONS FOR NON-CYCLONIC AREAS
MAXIMUM SUPPORT SPACINGS
Values are given in table 1 below for buildings located under the following conditions as specified by AS/NZS1170.2:2002 Wind Code:
- Max. Building Height - 3m
- Wind Velocity - 50 m/s
- Internal Pressure Coefficient - +0.2
- Terrain Category - 3
ALLOWABLE WIND PRESSURES
For buildings of different wind pressures and conditions, obtain maximum spans from table 2. Calculate the actual wind pressure according to AS.1170 and then determine the span required.
(Note: For cyclonic refer to local manufacturer or click here for more details.)
APPLICATION
COMPATABILITY
Lead flashings and copper or copper alloy materials should not be used with or in run-off situations with Zincolume sheeting. Also do not use lead head nails.
SEALING
Zincalume® or pre-painted materials cannot be soldered and to seal a suitable sealant and mechanical fasteners must be used.
MATERIAL SPECIFICATIONS
MATERIAL
The material used complies with:
Zincalume® Grade G550/AZ150 (550 MPa minimum Yield Stress) coated with a minimum 150 gm/sq m. zinc/aluminium alloy as specified in AS.1397 Ap. B. Pre-painted Zincalume® baked silicon modified polyester paint applied over Zincalume® steel sheet Grade G550/AZ150.
THICKNESS
Corrugated Iron is manufactured in two (2) thicknesses and grades of material as follows:
A. 0.42 BMT/Grade G550 for roof and wall applications.
B. 0.60 BMT/Grade G300 for curving and bullnosing applications.
MASS
0.42 0.60
Material Mass/Unit Area - 4.29 - 6.10kg/m²
Material Mass/Unit Length - 3.26 - 4.63kg/m
TABLE 1 - MAXIMUM SUPPORT SPACING
NOTES:
1. The recommended number of fasteners must be used.
2. These recommendations are based on tests carried out in accordance with AS.1532.
TABLE 2 - ALLOWABLE WIND PRESSURE
INSTALLATION
PRINCIPLE
The sheets of Corrugated Iron overlap each other and are fixed progressively along the building in the opposite direction to the prevailing weather. This gives complete weather protection and a fast and efficient method of installing the roof. Each sheet consists of an over rib and an under rib and when put together form an anti-capilliary drain which prevents water entry.
PREPARATION
Lift packs of Corrugated Iron onto the roof frame so that all sheets are the right way up and with the over edge facing the end of the roof where laying will commence.
Prevent roof damage by walking on at least 2 ribs distributing the weight over the foot and walk across the roof over the supports.
When the roof pitch is less than 25° or where there are extreme weather conditions, turn the sheet ends up approx. 80° at the high end and down approx. 15° at the gutter or low end. A shifting spanner can be used to do this.
END LAPPING
When two or more sheets are required for full length cover, start laying at the gutter and work up to the ridge and then start the next run. The minimum end laps required are:
Roofs - Pitch up to 15° - 230mm
Roofs - Pitch over 15° - 150mm
Walls - 100mm
End laps in roofs with a pitch of 5° (1 in 12) are to be sealed. End laps must be positioned over a support and the support spacings either side are to be that recommended for an end span.
FIXING
RECOMMENDED FASTENERS
Steel Framing (up to 5mm):
A Crest Fixed - No 12 x 35 Hex Head Self Drilling Tek with Neo. Washer.
B. Valley Fixed - No 10 x 16 Hex Head Self Drilling Tek with Neo. Washer.
Timber Framing:
A. Crest Fixed - No 12 x 50 Hex Head Type 17 Self Drilling Wood Screw with Neo. Washer.
B. Valley Fixed - No 12 x 25 Hex Head Type 17 Self Drilling Wood Screw with Neo. Washer.
SIDE LAP FASTENERS
These are added at the midspans of the sheets for support spacings over 900mm for roofs and 1200mm for walls to give weatherproofing. Use No 8 x 12 Hex Head Type S Self Drilling Screw with Neo. Washer OR 04 Monel Sealed Blind Rivets.
METHODS OF FIXING
Roofs - Pierce fix through crests only using 3 Fasteners/sheet OR 5 Fasteners/sheet depending on the location. At the end of sheets 5 Fasteners/sheet must be used.
Walls - Pierce fix through crests OR valleys. 3 Fasteners/sheet OR 5 Fasteners/sheet can be used depending on location. At the ends of sheets 5 Fasteners/sheet must be used. If valley fastening is used, side lap fasteners must be added beside each main fastener.
PRECAUTIONS
When unloading bundles of sheeting with a crane always use a spreader bar and fabric slings to prevent damage. When manually handling sheets use clean dry gloves and do not drag sheets over each other. Storage of sheets should be above ground and under cover.
Crest fasteners must not be overtightened but driven in until slight deformation of the rib is observed and the neoprene washer is fully sealed.
Do not locate fasteners less than 25mm from the end of sheets. Do not use punches to form holes for fasteners. Holes are to be drilled or self drilling fasteners are to be used.
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