Corrugated Roof Sheeting: Durable Solutions for Your Roofing Needs

Available Lengths, Installation, & Structural Considerations for CORRUGATED sheeting

Structural capabilities

Load span characteristics are to be used as a guideline only as purlin spacing also depends on other factors e.g. the wind conditions in a certain area, the type of structure or load bearing elements such as solar geysers and panels. An engineer should determine the purlin spacing of a structure after considering the complete design. Approximate spanning capabilities of Corrugated is as follows:

Available lengths

Corrugated is available in lengths of up to 14 metres with a length tolerance of -0 +5 mm. Sheet lengths up to 15.8m are available on enquiry.

When bullnoses and curves are designed a maximum permissible transport height of 4.3 metres is applicable.

Roof slope

When using Corrugated, the recommended minimum pitch for roof slopes in excess of 15.8m is 12.5º and for slopes less than 15.8m is 10º.

The minimum end laps for roof pitches >16º is at least 150 mm and 250 mm for other roofs. Side cladding end laps should be at least 100 mm.

It is recommended that end laps on roofs <16º are sealed with a bitumen sealing strip to ensure water tightness.

Fixing procedure

The required number of Corrugated sheets can be calculated as follows:

• Length of building plus gable overhangs - (minus) 76 mm
• Number of sheets = Meters required ÷ (divided by) 0.762 m (Cover width of sheet)
• The result of the calculation is the number of sheets required rounded up to the next sheet

Roof sheets and side cladding must be fixed with one-and-a-half corrugation side lap and fastened through the crests of alternate flutes to purlins using 38 mm Tek screws into steel purlins and 65 mm Tek screws in the case of timber roofs, all fasteners must incorporate a 19 mm bonded washer.

When Corrugated sheeting is double overlapped the covering width for 8.5 Corrugated changes to 535 mm and 10.5 Corrugated changes to 686 mm.

For a quick calculation, 3 fasteners per sheet per purlin can be used.

BULLNOSING, CRANKING & CURVING OF ROOF SHEETING

Bullnoses & centre cranks

Bullnosing and center cranking of a profiled sheet incorporates lateral rib indentations pressed in at uniform distances. Standard bullnoses are made with the narrow flute uppermost and the bend away from the angular inclination. Reverse bullnoses are made with the narrow flute downwards and with the bend into the narrow flute. Bullnoses and cranks can be at the end of a sheet or at any position along the length.

Bullnoses and center cranks can be done in a radius from 300 mm to 800 mm for bullnoses which are bent through 0 - 180 degrees, larger radii will be classified as a curve.

The maximum sheet length which can be bullnosed is 15 m, with a maximum height of 2 m. The minimum runout from the bullnose is 30 mm on one side with a minimum of 500 mm on the other side of the sheet.

The critical end of a bullnose must be specified in order to ensure consistent lengths.

Due to handling and transport limitations the maximum height of center and off-center cranks which can be manufactured is 2 m with a limitation of 12 m total sheet length.

0.50mm Material can only be bullnosed and cranked to a minimum radius of 450 mm.

Care must be taken when ordering bullnoses and curves as there are no broad or narrow flutes on a Corrugated 10.5 sheeting to differentiate between a normal or reverse bullnose.

Two items must be clearly indicated on a Corrugated 10.5 bullnose:

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1. The position of the “lip up” or “lip down” on the sheet.
2. The colour requirements

Crank curving

Corrugated material can be crank curved with the same process used for bullnosing but with manual handling to achieve the larger radius. In the case of Chromadek sheeting the colour can be specified on either side of the sheet.

Bullnoses will be priced as curves when the radius exceeds 800 mm. The maximum height of curves which can be handled is 2 m with a maximum sheet length of 12 meters.

On-site springing of Roof Sheets

For roofs gently curved on elevation sheets may be sprung on site. However, extreme caution should be used when attempting this procedure to prevent buckling or oil canning. 

Why NJR Steel Stands Out as Your Roofing Solution

Choosing NJR Steel for your roofing needs means selecting a partner committed to quality, durability, and customer satisfaction. With our comprehensive range of Corrugated sheeting options, along with customization choices, we ensure that your project benefits from the best roofing materials in the industry.

For more details on our Corrugated roof sheeting or to discuss your specific project requirements, please reach out to us. Our expert team is eager to assist you in selecting the ideal roofing solutions.

Trust in NJR Steel for all your roofing requirements, where excellence and customer satisfaction are our top priorities.

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