Stramit MegacladŽ Roof and Wall Cladding

  • Hi-tensile Steel - lightweight with high strength.
  • Economical - unique combination of features provides a lower installed cost.
  • Less Fasteners - reduces cost of screws and installation.
  • 800mm Cover - quick and easy installation.
  • Spaced Ribs - greater water carrying capacity providing longer runs.
  • 2" Minimum Pitch - reduces support structure.
  • Spring Curving - ideal for curved roofs.
  • Less Work - fewer turn-ups and downs, less flashing, notching and fewer fasteners to install.

 The wide cover, light weight and weather resistance of Stramit Megaclad® cladding make it perfect for many industrial, commercial and rural roofing and walling applications. Its optimized rib spacing and ease of assembly allow for economical and practical spans. The large water-carrying capacity and weather-tightness permit very low roof pitches, leading to further economies in the building structure.


Stramit Megaclad®
cladding is manufactured from hi-tensile G550 BlueScope Steel COLORBOND® XRW steel or BlueScope Steel ZINCALUME® steel. In some locations galvanised and Colorbond® Ultra steel may be available by arrangement. Colorbond® XRW (and Ultra) is in accordance with AS2728 - Category 3 and, for the substrate, with AS 1397. Zincalume® AZI50 and galvanised Z450 conform to AS1397. Stramit has a comprehensive range of Colorbond® colours as standard. Refer to the BlueScope Steel Colorbond® 18 colours chart available from Stramit, and ask your nearest Stramit location for colour availability. 

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

Adverse Conditions

Stramit Megaclad® 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® XRW ?
Colorbond® Ultra N/A N/A ?

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

  distance of site from
site exposure
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 Zincalume, Colorbond XRW and galvanised products avoid copper, lead, green or treated timber, stainless steel and mortar or concrete.
  • In addition galvanised products should not receive drainage from aluminium or any inert materials, such as plastics, glass, glazed tiles, Colorbond and Zincalume. Contact Stramit for more detailed information.


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)
  • The University of Sydney
  • University of Technology, Sydney
This ongoing research and development activity ensures that Stramit remains at the forefront of innovation, design and consumer information.

Architectural Specification 

This specification is contained in the Stramit CD-ROM 'Solutions in Steel', and can be easily loaded onto your documentation via the clipboard function. 

The roofing/walling shall be 0.42 (or 0.48) mm BMT Stramit Megaclad® cladding in continuous lengths with trapezoidal ribs 28mm high, spaced at 267mm centres. Sheeting material shall be protected steel sheet to Australian Standard AS 1397, with a minimum yield stress of 550MPa (Grade G550) 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 fixing 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. Flashings shall be provided in compatible materials as specified; minimum cover of flashing shall be 150mm. All sheeting shall be fixed in a workman-like manner, leaving the job clean and weathertight. Repair minor blemishes with touch-up paint supplied by the roof manufacturer. All debris (nuts, screws, cuttings, filings etc.) shall be cleaned off daily.


The spans shown below take account of 'normal' foot traffic and wind resistance including local pressure zone effects. Pressures are based on AS4055 or AS I 170.2 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.


roofs walls overhangs
Pressure (kPa)   internal
(end) span
Pressure (kPa)   internal
(end) span
strength double
strength double
N1 or Region A (sheltered suburban)
0.42 0.76 1.35 1250 1250 1500(1250) 0.61 1.04 2100 2300 2450(2000) 100 300
0.48 0.76 1.35 1500 1500 1800(1500) 0.61 1.04 2200 2450 2600(2150) 150 350
N2 or Region B (sheltered suburban) and Region A (exposed suburban)
0.42 0.78 1.94 1250 1250 1500(1250) 0.61 1.49 2100 2300 2450(2000) 100 300
0.48 0.78 1.94 1500 1500 1800(1500) 0.61 1.49 2200 2450 2600(2150) 150 350
N3 or Region A (rural) and Region B (exposed suburban)
0.42 1.18 2.96 1250 1250 1450(1200) 0.92 2.25 1700 1650 1900(1550) 100 250
0.48 1.18 2.96 1500 1500 1800(1500) 0.92 2.25 1800 2000 2300(1900) 150 300
Internal spans must have both end spans 20% shorter. Values are only valid for use with steel members of 0.75mm or thicker.
For more specific applications Stramit Megaclad® cladding must be designed to the pressure and foot traffic limitations below.


bmt (mm)
per sheet
pressure (kPa) at the spans (mm) shown
600 900 1200 1500 1800 2100 2400 2700 3000
  internal 3.18 2.31 1.72 1.31 1.02 0.81 0.64 0.50 0.39
0.42 3 equal 2.56 2.27 1.76 1.34 1.01 0.75 0.54 0.38 0.24
  double 3.86 2.30 1.56 1.12 0.83 0.63 0.47 0.36 0.26
  internal 2.97 2.97 2.67 2.13 1.63 1.19 0.83 0.52 0.26
0.48 3 equal 5.65 3.18 2.09 1.49 1.10 0.84 0.65 0.50 0.39
  double 6.44 3.38 2.10 1.41 0.99 0.70 0.50 0.34 0.22

bmt (mm)
per sheet
pressure (kPa) at the spans (mm) shown
600 900 1200 1500 1800 2100 2400 2700 3000
  internal 9.25 5.39 3.80 2.95 2.44 2.09 1.84 1.65 1.51
0.42 3 equal 12.43 6.05 3.48 2.49 2.06 1.86 1.78 1.74 1.74
  double 4.51 4.63 3.92 3.24 2.69 2.24 1.88 1.58 1.33
  internal 12.43 9.44 6.76 5.18 4.15 3.41 2.87 2.45 2.11
0.48 3 equal 12.43 8.74 5.42 4.07 3.44 3.13 2.96 2.87 2.83
  double 11.91 8.91 6.75 5.25 4.16 3.34 2.70 2.19 1.77

Foot Traffic

Foot traffic limits for Stramit Megaclad® 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 AS 1562 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.
per sheet
foot traffic limits
heavy normal controlled
    internal - 1500 1800
0.42 4 equal - 1250 1500
    double - 1250 1500
    internal 800 1800 2100
0.48 4 equal 600 1500 1800
    double 600 1500 1800
Tables are based on tests to AS1562 and AS4040 parts 0 and 1

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

Spring Curving 

Stramit Megaclad®
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
neutral radius
0.42 70 70 135 228 334
0.48 70* 80 135 228 334
*At these radii a maximum support spacing of 1200mm 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.

For more comprehensive information on spring curving Stramit Megaclad® cladding and other Stramit® roofing profiles refer to the Stramit® Spring Curving Guide.

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 Megaclad®
cladding has excellent water-carrying capacity. This and the sheeting stiffness enable roof slopes to be as low as 2° 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)
40 50 60 70 80 90 100 110 120 130 140
150   2.0 2.6 3.3 4.0 4.8
175 Minimum   2.0 2.3 3.0 3.8 4.7 5.8 6.3
200 Slope 2.0°   2.0 2.4 3.2 4.2 5.3 6.4 7.7 9.0
225   2.0 2.3 3.3 4.4 5.5 6.9 8.4 11 13
250   2.0 3.0 4.3 5.7 7.2 8.9 11 14 16
275   2.0 2.6 3.8 5.3 6.9 8.8 11 14 16 19
300   2.0 3.2 4.7 6.5 8.5 11 14 17 19 22
325 2.0 2.5 4.0 5.5 7.5 10 13 16 19 22 25
350 2.0 2.9 4.6 6.5 8.7 12 15 18 22 25  
375 2.0 3.7 6.0 7.8 11 14 18 21 25 Exceeds the 
400 2.6 4.4 6.5 9.0 13 16 20 23 scope of this manual 

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


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

  For steel (0.75bmt or greater)
- No. 12 x 45mm 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 65mm 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 Megaclad®
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.


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

Walk only in pans, or on ribs at purlin supports


Good Practice

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


Stramit Megaclad®
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 Megaclad® 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 tradesperson for a supply and fix price. Contact your nearest Stramit location for the names of tradespersons in your area. 

Ridge Capping
standard or custom dimensions
a range of custom flashings
Filler Strips
top and bottom; for eaves, ridge and joint sealing
Use only where sealing is preferred to ventilation
Insulation & roofing mesh
a range of mesh, sisalation, plain & foil backed blanket
Translucent sheeting
fibreglass sheeting in a range of shades and densities


Stramit Megaclad®
cladding is supplied cut-to-length. When designing or transporting long products ensure that the length is within the limit of the local Transport Authority regulations. The manufacturing tolerance on the length of product supplied is +0. -15mm.


Stramit Megaclad®
cladding can be ordered directly, through distributors, or supplied and fixed from a roofing contractor.


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 Megaclad® cladding, care should be taken to ensure that the load is spread to prevent damage.


Stramit Megaclad®
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.          

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
  • Bullnosing, Curving and Crimping
  • 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 and girts
  • Formwork decking
  • Roof and wall sheeting
  • Lightweight structural sections
  • Truss components
  • Gutters and downpipes
  • Fascias
  • Custom flashings
  • Insulating products
  • Fasteners

Design Registrations

Stramit Megaclad®
cladding is the subject of a design registration.


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-I
    (Steel roofing and walling products - selection guide)

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

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