How to Install Corrugated Iron Roof Sheets

Fastening sheets to supports

Our products are pierce-fixed to steel or timber supports.

You can place screws through the crests or in the valleys. To maximise water tightness, always place roof screws through the crests. For walling, you may use either crest or valley-fixing.

Always drive the screws perpendicular to the sheeting and in the centre of the corrugation or rib.

Side-laps

The product must be overlapped at the sides, not less than 1.5 corrugations. It is generally considered good practice to use fasteners alongside laps; however, when cladding is supported, as indicated in maximum support spacings, side-lap fasteners are not usually needed for strength.

Ends of sheets

It is usual to allow roof sheets to overlap into gutters by about 50 mm. The valleys of sheets should be turned down at the lower ends and at the upper ends.

Laying procedure

For maximum weather tightness, start laying sheets from the end of the building in the lee of the worst-anticipated or prevailing weather.

Lay sheets toward prevailing weather. Also, turning sheets on the ground is much easier and safer than on the roof.

Before lifting sheets onto the roof, check that they are the correct way up and that the overlapping side is towards the roof's edge from which installation will start.

Metal and Timber Compatibility

Lead, copper, bare steel and green or some chemically-treated timber are incompatible with this product; thus, don't allow any contact of the product with those materials or discharge rainwater from them onto the product. If there are any doubts about the compatibility of other products being used, please contact us.

Storage and Handling

Our product may be sharp and heavy. It is recommended that heavy-duty cut-resistant gloves and appropriate manual handling techniques or a lifting plan be used when handling the material. Keep the product dry and clear of the ground. If the stacked or bundled product becomes wet, separate it and wipe it with a clean cloth to dry it thoroughly.

Handle materials carefully to avoid damage: don't drag materials over rough surfaces or each other; don't drag tools over material; protect from swarf.

Swarf

Sweep all metallic swarf and debris from roof areas and gutters at the end of each day and complete the installation. Failure to do so can lead to surface staining when the metal particles rust.

Our product has a corrugated profile, equally at home with traditional and contemporary design. In addition, it is a wide, strong and lightweight profile that can be quickly and easily installed. Add up these features and have a steel roof or wall cladding that offers outstanding value.

The gently curving shape of the classic Australian roof is reflected in some of today’s most adventurous and dramatic designs.

Simple, low-cost fixing

Corrugated sheets can be fixed with hex head screws ensuring fast and simple installation with the recommended side lap (one and a half corrugations).

Colours

Our products are available in an attractive range of colours in colorbond® factory prepainted steel and unpainted zincalume® aluminium/zinc/magnesium alloy coated steel. In addition, standard colorbond® steel is available in a select range of contemporary colours suitable for all building projects. See our COLORBOND Colours page here.

Colorbond® steel with Thermatech® Technology

Thermatech® solar reflectance technology is now included in the standard COLORBOND ® steel palette. COLORBOND ® steel with Thermatech® technology reflects more of the sun’s heat, allowing both roofs and buildings to stay cooler in summer. In moderate to hot climates, compared to roofing materials of similar colour with low solar reflectance, COLORBOND ® steel with Thermatech® can reduce annual cooling and energy consumption by up to 20%.

Minimum roof pitch

A special anti-capillary forming in the side lap allows you to use custom orb (or Custom Blue Orb used on curved surfaces) for roof pitches as low as 5 degrees (1 in 12).

Sheet lengths

Sheet lengths of up to 24m can be used before an expansion joint is required for roof applications.

Lengths

Sheets are supplied custom cut.

Turning-up our products

With pliers, multi-grips, or a shifting spanner closed down to approximately 2mm, grip the valley corrugations 20mm in from the end of the sheet and turn up as far as possible. Be careful not to tear the sheet.

Masses Corrugated Roofing

Walking on roofs

When walking along the length of the corrugated roof, walk only in the pans. When walking across the width of the sheeting, walk over or close to the roofing supports. Generally, keep your weight evenly distributed over the soles of both feet to avoid concentrating your weight on either heels or toes. Always wear smooth soft-soled shoes; avoid ribbed soles that pick up and hold small stones, swarf and other objects.

Sealed joints

For sealed joints, use screws or rivets and neutral-cure silicone sealant branded as suitable for galvanised or zincalume® steel.

Laying procedure

For maximum weather tightness, start laying sheets from the end of the building in the lee of the worst anticipated or prevailing weather. Lay sheets toward prevailing weather. Also, it is much easier and safer to turn sheets on the ground than up on the roof. Before lifting sheets onto the roof, check that they are the correct way up and that the overlapping side is towards the roof's edge from which installation will start. Place bundles of sheets over or near firm supports, not at the mid-span of roof members.

Fasteners

All fastening screws must conform to AS3566 – class 3. They are to be hexagon headed and used with sealing washers for roofing and walling applications.

Cutting

Our corrugated products can be very easily cut, when required, by using tin snips, a power saw with a steel cutting blade or a power nibbler. For smaller areas, tin snips will be fine. Avoid using abrasive discs, which can cause burred edges and coating damage.

Condensation

The underside of metal deck roofs provides conditions under which condensation of water vapour will occur. Please consider the following:

Proprietary metal-strip roofing does not need the support of a (structural) deck, as this is usually omitted for the economy. Condensation will then form under the roof sheeting and drip from it in a manner of frost-drip familiar with corrugated galvanised steel roofs. Absorbent treatments applied to the underside of the sheeting and glass wool (bulk) thermal insulation material placed beneath the sheeting are valuable in reducing the likelihood of condensed water falling. It is commonly thought that condensation under metal roofing can be eliminated by liberal ventilation of the roof space. Unfortunately, that is not so, although some relief is possible.

On clear nights, roofs become several degrees colder than the adjacent atmospheric air so that air entering the roof space may be cooled by contact with the roof. However, the depression in temperature can be sufficient to cause condensation of water from the inflowing air. In other words, uninsulated metal roofs, whether foil laminated or not, are more likely to suffer from condensation than an insulated roof system. 

In conventional buildings, particularly those heated in winter, condensation of water vapour will often occur to such an extent that ceilings will become stained.

A vapour barrier underneath the blanket insulation is essential to prevent moisture from inside the building from penetrating and wetting the blanket insulation.

In icy climates and where sufficient air space exists between the roof sheeting and the blanket insulation, condensation is likely to drip onto it. The insulation blanket should be covered with a second vapour barrier, such as reflective foil sarking or plastic sheeting in such cases. For more temperate climates where the moisture will evaporate during the day and the roof space is adequately ventilated, the upper vapour barrier may not be necessary,

In buildings without ceilings, such as factories, condensed water may fall on the machinery or stock in the space below.

Footnote:

**Non-cyclonic areas**

The above information is suitable for use only in areas where a tropical cyclone is unlikely to occur, as defined in AS 1170.2:2002.