Stramit Longspan® Roof and Wall Cladding

  • 700mm Cover – quick installation and easy handling.
  • Easy Fixing – conventional through fixed screws maximise performance and installation.
  • Hi-Tensile Steel – light weight and high strength with improved damage resistance.
  • Spring Curving – new data for curved roofs.
  • Design Flexibility – long lengths and anti-capillary side laps enable Stramit® Longspan cladding to be used effectively on applications from vertical wall cladding and fascias to roofs with pitch as low as 1.5°.
  • Fully Tested – a full range of load performance tables to suit most applications.
  • Extended Spans – strength and rigidity of the profile allows economical construction.


The striking linearity, strength, wide cover, light weight and weather resistance of Stramit® Longspan cladding make it perfect for many commercial roofing and walling applications. Its excellent strength and ease of assembly allow for long, economical spans.The good water-carrying capacity and weather-tightness permit very low roof pitches, leading to economies in the building structure.

Stramit® Longspan cladding is also used for domestic applications, where a strong but uniform appearance is desired.


Stramit® Longspan cladding is manufactured from hi-tensile G550 colour coated steel or alloy coated steel. In some locations galvanised and severe environment colour coated steel may be available by arrangement. Colour coated steels are in accordance with AS2728 – Category 3 and, for the substrate, with AS1397. Zinc-aluminium alloy coated AZ150 and galvanised Z450 conform to AS1397.

Stramit has a comprehensive range of colours as standard.  Ask your nearest Stramit location for colour availability.

SHEETING MASS (kg/m2 of roof area)
  Zincalume Colorbond Galvanised
0.42mm BMT 4.66 4.74 5.07
0.48mm BMT 5.29 5.37 5.70

Adverse Conditions

Stramit® Longspan 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® ?
Colorbond® Ultra 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 consult 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 zinc-aluminium alloy coated steel, colour coated steel and galvanised steel roofs avoid copper, lead, green or treated timber, stainless steel and mortar or concrete.

In addition galvanised steel roofs should not receive drainage from aluminium or any inert materials, such as plastics, glass, glazed tiles, colour coated and zinc-aluminium alloy. 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
  • Monash University
  • University of Queensland
  • 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 can be found on the Stramit web site and can be easily downloaded onto your documentation.

The roofing/walling shall be 0.42 (or 0.48) mm BMT Stramit Longspan® cladding in continuous lengths with trapezoidal ribs 27mm high, spaced at 100mm centres. Sheeting material shall be protected steel sheet to Australian Standard AS1397, with a minimum yield stress of 550MPa (Grade G550) and an AZ150 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 if required. 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 supplied 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 sheeting 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 AS1170.2 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.


Foot Traffic

Foot traffic limits for Stramit Longspan® 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
  internal - 2100 2400
0.42 equal - 1750 1800
  double - 1750 1800
  internal 800 2700 3000
0.48 equal 600 2250 2250
  double 600 2250 2250
Tables are based on tests to AS1562 and AS4040 parts 0 and 1

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

Spring Curving

Stramit Longspan® 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 30* 88 78 131 192
0.48 20* 113 78 131 192
*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 Longspan® 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 Longspan® cladding has a superior water-carrying capacity, to most close pitched trapezoidal profiles. This and the decking stiffness enable roof slopes to be as low as 1.5° 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)
20 25 30 40 50 60 70 80 90 100 110
150   1.5 2.2 3.3 4.6 5.4 7.5 9.5
175 Minimum   1.5 2.0 3.2 4.7 6.4 8.3 11 14
200 Slope 1.5°   1.5 2.8 4.6 6.5 9.0 12 15 18
225   1.5 2.2 3.8 6.0 8.5 12 15 19 22
250     1.5 2.8 5.0 7.5 11 15 19 23  
275   1.5 1.7 3.6 6.0 9.3 14 18 22  
300   1.5 2.0 4.6 7.5 12 16 21  
325   1.5 2.7 5.3 9.0 14 19 25   Exceeds the
350 1.5 1.9 3.2 6.2 11 16 22   scope of
375 1.5 2.4 3.8 7.5 13 18 25   this manual
400 1.6 2.7 4.3 8.0 15 20  

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

Cyclonic Areas

Cyclonic Data for Stramit Longspan® cladding can be found in the Stramit Cyclonic Areas Guide.

Information on the use of Stramit Longspan® cladding in the Darwin area can also be found in deemed-to-comply sheets No M/109/11 and M/109/12. These are available from Stramit.


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

Fastener Locations

Stramit Longspan®
cladding can be fixed with either 3, 4 or 5 fasteners per sheet at each batten/purlin to meet the required performance values, as shown below:


Stramit Longspan® cladding is readily installed with or without fibreglass insulation blanket. If practical lay sheets in the opposite direction to prevailing weather. Installation of Stramit Longspan® cladding is a straightforward procedure using the following fixing sequence:

  1. Ensure all purlins are in line and correctly installed and that mesh and blanket (if specified) are in place.
  2. Position and fix the first sheet ensuring the correct sheet overhangs (minimum 50mm). Ensure that screws are not overtightened.
  3. Continue to fix subsequent sheets checking that sheet ends at the lower edge are exactly aligned.
It is important that the underlap of one sheet does not protrude beyond the overlap of the next - if this is unavoidable, the underlap must be trimmed locally or water ‘drawback’ may occur.
  1. Measure the overall cover width at top and bottom of the sheets from time to time to avoid ‘fanning’.
  2. For roof spans exceeding 900mm and wall spans exceeding 1200mm, stitch the sidelaps at midspan.
  3. Turn up the pans at the upper roof edge and turn down the pans at the lower edge and install flashings.
  4. Clean up the roof after each days work, removing all screws, cuttings, swarf etc, and leave roof clean and watertight.

Stramit Longspan® 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 Longspan® 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.


Prices on Stramit Longspan® 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.

Related Products

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 Longspan® 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 Longspan® 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 Longspan® cladding, care should be taken to ensure that the load is spread to prevent damage. Packs must never be placed onto unclad purlins except directly above portal frames


Stramit Longspan® 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. Please contact your nearest Stramit location, or visit to download this manual or any of the many others available.


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.

Your IP Address is:
Copyright © 2020 KFC Roofing Supplies