Stramit® Curved Corrugated & Bullnose Roof Cladding

  • Design flexibility - expands the versatility of traditional corrugated roofing by increasing flexibility of design
  • Variety of shapes - can be formed into a wide variety of curved shapes and radii down to a nominal 500mm minimum
  • Compatible with standard Stramit® Corrugated sheeting - profile compatibility allows end lapping on long runs
  • Easy fixing - conventional through-fixed screws maximise performance and ease of installation
  • 762mm cover - quick installation and easy handling
  • G300 curving quality base steel - also available as flat sheets to ensure matching profile on end laps
  • Fully tested - full range of load performance tables to suit most applications.


Stramit® Curved Corrugated
steel roofing can be pre-curved to produce a variety of interesting effects that enhance both modern and traditional building designs. Straight sheets can be combined with convex and concave curves to create highly original and aesthetically pleasing roof shapes. The heritage bullnose veranda is the best-known application of curved corrugated sheeting but by no means the only one. 

Stramit® Curved Corrugated
roofing is also a popular choice on contemporary steel-roofed homes and commercial buildings.


Stramit® Curved Corrugated
cladding is manufactured from G300 BlueScope Steel COLORBOND® Ultra steel or BlueScope Steel ZINCALUME® steel. In some locations galvanised and BlueScope Steel COLORBOND® Stainless steel may be available by arrangement. BlueScope Steel COLORBOND® Ultra (and Stainless steel) is in accordance with AS2728 - Category 3 and, for the substrate, with AS 1397. BlueScope Steel ZINCALUME® AZ 150 and galvanised Z450 conform to AS1397. 

Stramit Building Products has a comprehensive range of BlueScope Steel COLORBOND® colours as standard. Refer to the BlueScope Steel COLORBOND® 18 colours chart available from Stramit, and ask your nearest Stramit office for colour availability.

SHEETING MASS (kg/m2 of roof area)
thickness bmt grade Zincalume Colorbond Galvanised
0.60mm 300MPa 6.02 6.09 6.39


Stramit has in-house, purpose built, testing equipment used to design, develop and improve products for the Australian market. In addition many Stramit products are tested or witnessed by independent organisations. These include:
  • Cyclone Structural Testing Station
    (James Cook University)
  • University of Queensland
This ongoing research and development activity ensures that Stramit remains at the forefront of innovation, design and consumer information

Adverse Conditions 

Stramit® Curved Corrugated
cladding will give excellent durability in almost all locations. It is however important to choose the correct coating for each application environment. 

The table below shows the suitability of coating types for different exposure conditions. 

suitability of
coating type
site exposure condition
benign moderate severe very severe
Zincalume AZ150 ? ?
Galvanised Z450 ?
Colorbond ULTRA ?
Colorbond Stainless N/A N/A ?
? Question marks indicate conditions where durability may be diminished, depending on the particular application. 

The approximate site exposure conditions in the table above are defined below.

site exposure
distance of site from
active surf
calm, still
salt water
fossil fuel
benign 1000m + 100m + 500m + 500m +
moderate 400m-1000m 0-100m 250m-500m 250m-500m
severe 100m-400m N/A 100m-250m 100m-250m
very severe 0-100m N/A 0-100m 0-100m

The suitability and exposure tables above are guidelines only; conditions will vary from site to site. If in any doubt about the choice of coating for a particular application contact your nearest Stramit office for advice.


All building products need to be checked for compatibility with adjacent materials. These checks need to be for both direct contact between materials, and where water runs from one material to another. The following guidelines generally avoid material incompatibility:
  • For BlueScope Steel ZINCALUME®, BlueScope Steel COLORBOND® Ultra and galvanised roofs avoid copper, lead, green or treated timber, stainless steel and mortar or concrete.
  • In addition galvanised roofs should not receive drainage from aluminium or any inert materials, such as plastics, glass, glazed tiles. BlueScope Steel COLORBOND® and BlueScope Steel ZINCALUME® steel. Contact Stramit for more detailed information.

Architectural Specification 

The roofing/walling shall be 0.60mm BMT Stramit® Corrugated in continuous lengths with sinusoidal curved ribs 16mm high spaced at 76.2mm centres in accordance with AS 1445, curved to a radius of __ mm. Sheeting material shall be protected steel sheet to Australian Standard AS 1397 with a minimum yield stress of 300MPa (Grade 300) and an AZ 150 zinc-aluminium coating with or without an oven-baked paint film of selected colour. The sheeting shall be fixed to the purlins/girts in accordance with the manufacturer's recommendations. Suitable fixed screws in accordance with Australian Standard AS3566, Class 3, shall be used at every support with side lap fasteners installed at mid span. Sheets shall be laid in such a manner that the approved side lap faces away from the prevailing weather. 

A minimum of 50mm shall be provided for projection into gutters. Flashing shall be supplied in compatible materials as specified; minimum cover of flashing shall be 150mm. AII sheeting shall be fixed in a workman-like manner, leaving the job clean and weather tight. All debris (nuts, screws, cuttings, filling, etc.) shall be cleared off daily.

Typical Curved Profiles 


The spans shown below take account of 'normal' foot traffic and wind resistance including local pressure zone effects. Pressures are based on AS40SS or AS 1170.2 section 2. Where the two standards differ, the worst case has been taken for each classification. Data should only be used for buildings 7m or less in height, 1000m2 or less in area and unaffected by land topography. 

For bullnosed roofs the span is to be taken as the sheet length between fastening positions at supports.            


bmt (mm)
per sheet
pressure (kPa) at the spans (mm) shown
600 900 1200 1500 1800 2100 2400 2700 3000
0.60   internal 4.76 3.57 2.63 1.95 1.46 1.08 0.79 0.55 0.36
3 equal 4.45 3.33 2.36 1.83 1.27 1.01 0.74 0.52 0.34
  double 4.45 3.33 2.36 1.83 1.27 1.01 0.74 0.52 0.34
  single 2.80 2.41 1.73 1.03 0.61 0.37 0.25 0.20  
  internal 9.54 6.39 3.81 2.54 1.81 1.34 1.02 0.79 0.62
5 equal 9.54 4.61 2.74 1.81 1.27 0.92 0.68 0.51 0.38
  double 9.54 4.61 2.74 1.81 1.27 0.92 0.68 0.51 0.38
  single 6.84 5.31 2.18 1.09 0.63 0.41 0.31 0.25 0.23

bmt (mm)
per sheet
pressure (kPa) at the spans (mm) shown
600 900 1200 1500 1800 2100 2400 2700 3000
0.60 3 internal 12.43 9.93 9.53 8.71 7.58 6.46 5.35 4.33 3.41
equal 10.20 8.88 8.14 6.90 5.70 4.51 3.44 2.50 1.67
double 12.00 10.40 9.58 8.19 6.70 5.30 4.05 2.94 1.96
single 10.36 10.36 9.17 8.01 6.71 5.55 4.60 3.81 3.14
5 internal 12.43 12.43 12.43 12.43 11.42 6.69 8.03 6.50 5.11
equal 11.49 11.49 11.49 10.44 8.54 6.76 5.16 3.75 2.50
double 11.49 11.49 11.49 11.49 10.05 7.95 6.07 4.41 2.95
single 12.43 10.36 9.17 8.01 6.91 5.93 5.07 4.32 3.66
Tables based on testing to AS1562 and AS4040 parts 0, 2 and 3. Internal spans must have both end spans 20% shorter.
Values only valid for use with steel support members of 0.75mm or thicker.

Foot Traffic 

Foot traffic limits for Stramit® Curved Corrugated cladding are shown for three alternate foot traffic categories. These are:
  • High Maintenance - for applications with repeated maintenance, particularly where personnel may be unfamiliar with correct procedures for walking on metal roofs.
  • Normal - based on traditional expectations, with moderate maintenance foot traffic using designated foot paths.
  • Controlled - spans that conform to AS1562 but require minimal careful foot traffic only on the designated foot path. Suggested for use only where occasional aesthetic imperfections from foot traffic are acceptable.
foot traffic limits
heavy normal controlled
0.60 internal - 1200 1900
equal - 900 1600
double - 900 1600
single - 700 900
Tables are based on tests to AS1562 and AS4040 parts 0 and 1

For more information on foot traffic performance of Stramit® Curved Corrugated cladding and other Stramit® roofing profiles refer to Stramit's Foot Traffic Guide. 

Spring Curving 

Stramit® Curved Corrugated
cladding can be spring curved, concave and convex, including curved ridges, provided it is sealed at the apex, and within the recommended limits below: 

  performance restricted restricted by drainage at the
rainfall intensities shown
      maximum radius (m) at
neutral radius
0.60 8* 26 37 63 92
*At these radii a maximum support spacing of 900mm applies, and limit state pressure capacities are reduced by 14% for serviceability and 7% for strength. These reductions apply proportionately up to the lowest neutral radius. Minimum 5 fasteners required per sheet at ends.

For more comprehensive information on spring curving Stramit® Curved Corrugated cladding and other Stramit® roofing curved profiles refer to the Stramit Design Guide 'Spring Curving'. 

Thermal Expansion

All metal roof sheeting is subject to thermal expansion and, where there is a temperature difference between the sheeting and the structure, this needs to be accommodated. The colour of the sheeting will affect the amount of thermal expansion, and whether the sheet is flat or curved will affect its ability to resist without problems. Sheet lengths should be limited to those shown below. 

roof colour light dark
Flat 25 17
Spring-curved 20 17

Water Carrying 

Stramit® Curved Corrugated
cladding has limited water-carrying capacity. Roof slopes can be as low as 5° for many applications. Roof run lengths are the combined lengths of all roof elements contributing to a single pan drainage path. This can include the roof length upstream of a roof penetration that concentrates flow into other pans. The table below gives slopes for 100 year return period rainfall intensity.

Rainfall Intensity
total roof run length (m)
10 15 20 25 30 35 40 45 50 55
150   5.0 7.0 11 14 18 23
175 Minimum   5.0 7.0 11 15 20  
200 Slope 5° 5.0 6.0 10 15 21  
225   5.0 8.5 14 20  
250   5.0 6.0 12 18  
275   5.0 8.0 15 23  
300   5.0 11 19   Exceeds the  
325 5.0 5.5 13 22   scope of  
350 5.0 7.0 16 25   this manual  
375 5.0 8.5 17  
400 5.0 10 20  

For more information on water carrying performance of Stramit® Curved Corrugated cladding and other Stramit® roofing profiles refer to Stramit's Roof Slope Guide.

Darwin Area 

Information on the use of Stramit® Curved Corrugated cladding in the Darwin area can be found in deemed-to-comply sheets No's M 103/5, 6 and 7. These are available from Stramit or the Darwin Area Building Manual.


All external fastening screws must conform to AS3566 - Class 3 as a minimum. They are to be hexagon headed and must be used with neoprene washers. For connecting to purlins or top hats use:        

Fastener Locations 

Stramit® Curved Corrugated
cladding can be fixed with either 3 or 5 fasteners per sheet at each batten/purlin to meet the required performance values, as shown below: 


  For steel (0.75bmt or greater)
- No.12 x 35mm self-drilling and threading screws for crest fixing
- No.10 x 16mm self-drilling and threading screws for pan fixing to walls
  For timber (F11 or better)
- No. 12 x 50mm type 17 screws for crest fixing
- No.10 x 25mm type 17 screws for pan fixing to walls
  Side Laps
- No. 8 x 12mm ‘S’ point screws, or
- 3.2mm diameter sealed aluminium pop rivets


Stramit® Curved Corrugated
cladding is suitable for use with insulating blanket. Glasswool blanket up to 50mm thick can be readily used. Increased thicknesses require longer fasteners and greater care in installation. For domestic applications Stramit recommends that insulation is always used. 


As with all roofing products, we recommend extra caution be taken when walking on the roof. When walking on Stramit® Curved Corrugated cladding roofing always wear flat rubber soled shoes and place feet only on the ribs, taking care to avoid the last rib or two near edges of the metal roof area. 

Good Practice 

Stramit recommends that good trade practice be followed when using this product, such as that found in Australian Standards Handbook HB39.


Stramit® Curved Corrugated
cladding can be easily cut, where required, using a power saw with a steel cutting blade or a power nibbler and, for localised cutting, tin snips. Avoid the use of abrasive discs as these can cause burred edges and coating damage. Please dispose of any off-cuts carefully.


Prices on Stramit® Curved Corrugated cladding and its accessories can be obtained from your nearest Stramit location or distributor of Stramit® products. As Stramit does not provide an installation service, ask your trades person for a supply and fix price. Contact your nearest Stramit location for the names of tradespersons in your area. 

Bullnosing/Curving Information

To ensure that you receive product to suit your application it is essential that detailed information be supplied. 

Please supply template and all information wherever possible.

For curving purposes it is necessary to produce a sheet with a minimum straight section at the sheet end (A) of 100mm. All or part of this straight section can be removed upon request (docked). 

Related Products


Stramit® Curved Corrugated
can be supplied in any length from 500mm to 4000mm. Longer lengths may be supplied by arrangement. When measuring it should be noted that at the end of each curve adjacent to the curve there is at least 100mm that cannot be curved which must be allowed for. The manufacturing tolerance on the length of products supplied is +0, -15mm. 


Minimum radii may vary depending on your Stramit Building Products production centre. A call to your local Stramit office is recommended when planning to use Stramit® Curved Corrugated. When ordering Stramit® Curved Corrugated always provide a template that describes the desired curve. If you require both curved and straight product that will be end lapped, always order products at the same time. This will ensure that both straight and curved material are of a compatible profile. For best results use G300 material for straight sheets to ensure matching profiles. For lengths exceeding 4 metres please contact your local Stramit office. 


Delivery can normally be made within 48 hours, subject to the delivery location, quantity and material availability, or can be at a pre-arranged date and time. Please ensure that suitable arrangements have been made for truck unloading, as this is the responsibility of the receiver. Pack mass may be up to one tonne. When lifting Stramit® Curved Corrugated cladding, care should be taken to ensure that the load is spread to prevent damage. Packs must never be placed onto unclad purlin battens except directly above support frames. 


Stramit® Curved Corrugated
cladding should be handled with care at all times to preserve the product capabilities and quality of the finish. Packs should always be kept dry and stored above ground level while on site. If the sheets have become wet, they should be separated, wiped and placed in the open to promote drying.


Exterior surfaces of metal products unwashed by rain can benefit from occasional washing to remove build-up of corrosive salts. Walls beneath eaves or awnings are such a situation. 


Should it become necessary to wash Stramit® roof sheeting follow the procedure below.
  1. Wash the surface with a mild solution of pure soap or non-abrasive, non-toxic, kitchen detergent in warm water using a sponge, soft cloth or soft bristle nylon brush.
  2. Thoroughly rinse the water clean immediately after cleaning.
WARNING - Never use abrasive or solvent type cleaners (e.g. turps, petrol thinners or kerosene) on BlueScope Steel COLORBOND® steel.

Further Information 

As well as our standard range of Technical Manuals, Installation Leaflets, Case Studies and other promotional literature Stramit has a series of Guides to aid design. These include:
  • Concealed Fixed Decking
  • Roof Slope Guide
  • Foot Traffic Guide
  • Acoustic Panels
  • Cyclonic Areas
  • Spring Curving Guide
Please contact your nearest Stramit location for any of these guides or other literature.

Other Products 

Stramit offers a wide range of building products including:
  • Purlins & Girts
  • Formwork decking
  • Roof and wall sheeting
  • Lightweight structural sections
  • Truss components
  • Gutters and downpipes
  • Fascias
  • Custom Flashings
  • Insulation products
  • Fasteners


In preparing this document reference has been made to:
  • Standards Australia Handbook - HB39
    (Installation code for metal roof and wall cladding)
  • BlueScope Steel - Technical Bulletin TB-4
    (Maintenance of Colorbond® prepainted steel roofing)
  • BlueScope Steel - Technical Bulletin TB-1
    (Steel roofing and walling products - selection guide)

This product was added to our catalog on Monday 13 July, 2009.

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