Suitability and Compatibility
Can I still use COLORBOND® steel close to the ocean?
Please view our page Effect of Location.
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Can I use COLORBOND® steel as a retaining wall, or garden bed?
In Concrete
ZINCALUME® steel (and COLORBOND® steel manufactured with a ZINCALUME® steel substrate), are NOT recommended for immersion in wet cement as rapid corrosion and degradation of the coating alloy will occur. The recommended product for use with uncured concrete and highly alkaline bonding materials is galvanised steel. COLORBOND® steel is available with a galvanised substrate - one common use being posts for fencing.
In Soil
The construction of gardens adjacent to buildings or fencing by placing soil directly against ZINCALUME® steel or COLORBOND® steel sheeting is strongly discouraged as corrosion of the sheeting will rapidly occur about the area covered with soil.
Moisture or moisture retaining materials should not be permitted to remain in intimate contact with ZINCALUME® steel, COLORBOND® steel or galvanized steel. Such contact will ultimately result in corrosion of the material.
The major factors influencing corrosion are the continual retention of moisture and the differential concentration of oxygen at the material surface. Gutters are frequent victims, with insufficient fall leading to ponding of water.
The accumulation of debris (leaf matter, dirt etc) which results in continual immersion, is the most common reason for unsatisfactory performance of guttering.
In typical garden applications such as fence panels, garden sheds and walling the build up of grass cuttings, leaves, soil from gardens, mulch, compost, sand and ashes must be avoided.
For more information, please Download Corrosion Technical Bulletin CTB 16 - Immersion.
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Can I use COLORBOND® steel as formwork, or cover it with concrete?
Please view our page: Avoid corrosion from contact with concrete or soil.
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Can I use COLORBOND® steel directly on steel beams?
The use of uncoated steel supports for ZINCALUME® steel or COLORBOND® steel is discouraged as the possibility of corrosion of the overlying sheeting may be greatly enhanced. Where heavy steel sections such as hot rolled steel angles are necessary for structural requirements, the steel sections must be post painted with an appropriate high build industrial coating system or galvanised.
Such procedures are regarded as imperative to prevent the deterioration of the steel member and consequently, the rapid degradation of the sheeting. Advice should be sought from reputable coating manufacturers in regard to the specification of an appropriate coating system which will offer suitable corrosion resistance for the particular exposure environment.
For more information, please Download Corrosion Technical Bulletin CTB 9 - Contact With Unprotected Steel Supports.
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Can I use lead flashings with my roof made from COLORBOND® steel?
Lead is not compatible with ZINCALUME® steel or COLORBOND® steel. ZINCALUME® steel or COLORBOND® steel is also prone to corrosion when in contact with or receiving run off water from lead.
Instead of lead, the recommended flashing materials that can be formed on site are soft zinc or aluminium.
Popular flashing materials include COLORBOND® steel or ZINCALUME® steel sheet formed to suit the application. While zinc-coated steel can be used with ZINCALUME® steel or COLORBOND® steel, its generally lesser life span makes it impractical in the long term.
When using COLORBOND® Stainless steel we recommend the use of stainless steel flashing products. Flashings made from zinc coated, zinc/aluminium alloy coated and COLORBOND® prepainted steel should not be used with COLORBOND® Stainless steel.
Roof penetration flashings are also available in a wide range of rubber and aluminium materials, and these are commonly used.
In the event of roof renewals where lead flashing already exists and its re-use is desirable, the ZINCALUME® steel or COLORBOND® steel should be insulated from the lead by a suitable barrier. This can be achieved by painting the underside of the lead. Plastic film can also be used to separate the surfaces, provided it is robust enough and will not tear, eg Polyethylene damp-course.
Painting the underside of lead flashings already existing on an old building well enough to ensure separation is not easy. Polyethylene damp-course placed between the lead and ZINCALUME® steel or COLORBOND® steel sheet is a better alternative.
Lead in the water run-off can be avoided by painting the top surface of the lead flashing. Applying two or three coats of water-based acrylic is suitable but any painting should be maintained so that it will not break down and expose any of the lead surface.
This information is intended as a guide only. For further information, please Download Technical Bulletin TB 8 - Flashing Materials for ZINCALUME® steel and COLORBOND® steel sheet.
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My fence, wall or shed sides are buried in dirt and soil. Will this affect the sheeting?
In Concrete
ZINCALUME® steel (and COLORBOND® steel manufactured with a ZINCALUME® steel substrate), are NOT recommended for immersion in wet cement as rapid corrosion and degradation of the coating alloy will occur. The recommended product for use with uncured concrete and highly alkaline bonding materials is galvanised steel. COLORBOND® steel is available with a galvanised substrate - one common use being posts for fencing.
In Soil
The construction of gardens adjacent to buildings or fencing by placing soil directly against ZINCALUME® steel or COLORBOND® steel sheeting is strongly discouraged as corrosion of the sheeting will rapidly occur about the area covered with soil.
Moisture or moisture retaining materials should not be permitted to remain in intimate contact with ZINCALUME® steel, COLORBOND® steel or galvanized steel. Such contact will ultimately result in corrosion of the material.
The major factors influencing corrosion are the continual retention of moisture and the differential concentration of oxygen at the material surface. Gutters are frequent victims, with insufficient fall leading to ponding of water.
The accumulation of debris (leaf matter, dirt etc) which results in continual immersion, is the most common reason for unsatisfactory performance of guttering.
In typical garden applications such as fence panels, garden sheds and walling the build up of grass cuttings, leaves, soil from gardens, mulch, compost, sand and ashes must be avoided.
For more information, please Download Corrosion Technical Bulletin CTB 16 - Immersion.
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What difference does the thickness of the COLORBOND® steel make?
The thickness of sheeting is normally measured as its BMT (base metal thickness). For steel of the same grade and profile, a higher BMT generally means the sheet can span further between supports.
Care should be taken when referencing thickness because some manufacturers will quote Total Coated Thickness (TCT). This is the thickness of the total sheet and will be higher than its BMT (which measures only the thickness of the steel beneath any coatings). eg. 0.42mm BMT is the same as 0.47mm TCT.
Increased thickness will not increase the life of a product, and direct comparisons of BMT between profiles or steel grades cannot be made. The profile manufacturer should be able to provide you with spanning information for the profile and BMT you are using.
Soft (or lower strength) steels will generally be thicker than hard, high strength (or hi-tensile) steels, and are commonly used in applications where tight curving is required.
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What is the difference between the standard, Ultra, Stainless and Metallic ranges of COLORBOND® steel?
Standard COLORBOND® steel is the product you're most likely to see on the majority of applications and locations across Australia. However, there are some environments and applications for which it isn't suited, and for these BlueScope Steel has developed specialised products. COLORBOND® Ultra steel and COLORBOND® Stainless steel grades are made for more severe environments, such as those exposed to industrial emissions or close to the sea. COLORBOND® Metallic steel has a unique metallic paint finish and is commonly used for prestige projects. You can find out more by viewing our pages: Effect of Location and Look Your Best: COLORBOND® Metallic steel.
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What other building materials can I use alongside COLORBOND® steel? What metals are OK to use in contact with COLORBOND® steel and what should I avoid?
Do not allow any metals other than aluminium, galvanised steel, ZINCALUME® steel or zinc to come into direct contact with COLORBOND® steel. Any direct contact between any other metals (eg. copper and lead) and COLORBOND® steel can result in corrosion. Especially take note of the following:
- Copper pipes and lead flashing should not come in direct contact with either ZINCALUME® steel or COLORBOND® steel. If the building design is such that water will flow from lead flashing onto ZINCALUME® steel or COLORBOND® steel, then the flashing should be painted.
- Water from copper pipes should not be directed onto COLORBOND® steel or ZINCALUME® steel.
- Stainless steel fixings and fixings containing copper should also not be used with ZINCALUME® steel or COLORBOND® steel.
- Fasteners conforming to AS3566 Class 3 or 4 are acceptable depending on the location of the product. If you have any questions, ask your supplier or contact us.
- This information is intended as a guide only. For more information, on our Corrosion Technical Bulletins, Download Corrosion Technical Bulletin CTB 12 - Dissimilar Metals (283 KB).
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What sealants (silicone) can I use with COLORBOND® steel?
Neutral Cure silicone rubber sealants are the only sealants recommended for use with COLORBOND® steel and ZINCALUME® steel. Look for the words "Neutral Cure" on the sealant cartridge to make sure. View our page: Select a sealant for the job.
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Will contact with timber, including treated pine, affect COLORBOND® steel?
Green timber or timber treated with copper chromium arsenic (CCA) should not come into direct contact with galvanized steel, ZINCALUME® steel or COLORBOND® steel because acidic substances from these timbers have a corrosive effect on the metallic coating. The time of wetness of the metal surface is a factor in the overall corrosion mechanism (the longer the product is wet, the greater the corrosion).
Even run off from CCA treated timber can contain corrosive leachate which will cause corrosion if it contacts galvanized steel, ZINCALUME® steel or COLORBOND® steel.
BlueScope Steel recommend against the use of CCA treated timbers for high moisture situations such as roof and ceiling batons, composite fence constructions and built up flooring or external decking which may utilise a metallic coated steel structural support system.
If CCA treated timbers must be used, the timber and/or steelwork must be sealed by fully painting the material prior to installation.
The use of kiln dried or appropriate dried timber species is recommended for any situation where intimate contact between the metallic coated steel and timber is considered.
For more information, please Download Corrosion Technical Bulletin CTB 13 - Contact With Timber
