Colorbond

Contact with, or runoff from, some materials can damage coated steel products. Buildings can also be susceptible
to condensation on inside surfaces. The materials include certain metals, treated timbers and chemicals.
• Don’t allow any contact of coated steel products with incompatible materials.
• Don’t allow discharge of rainwater from incompatible materials onto coated steel products.
• Ensure that supporting members are compatible with the coated steel products or, alternatively, appropriately
coated. Incompatible materials include: lead, copper, monel metal, bare steel, stainless steel (except with colorbond ®
stainless cladding), carbon (in pencils and some rubbers), green or some chemically-treated timber (like CCA or tanalith
treatments), materials subject to cycles of dryness and wetness or which have excessive moisture content (such as
improperly-seasoned timber), wet and dry concrete, soils, vegetable matter, cleaning agents (e.g. brick cleaning)
and any material which will inhibit normal exposure to the atmosphere. When moisture is present and two dissimilar metals are in
contact, accelerated galvanic corrosion can affect one of the surfaces. This type of corrosion can also occur when
water flows over dissimilar metals. Properly designed flashings help to keep the cladding dry
and help to divert moisture and debris away from joins. To avoid ponding, all flashings should have a minimum fall of
1.5°. Roofers and designers should consider compatibility issues when selecting materials in a roof or wall system
Furthermore placing solar collectors, air-conditioning units or walkways on top of roof cladding need to consider
discharge from such systems. Severe corrosion may occur If materials are not combined correctly.
Lead flashing is not recommended, however it will usually be retained when re-roofing, because it is usually
cemented into the structure. In these cases: 

• the top surface of the lead flashing must be painted with a good quality exterior paint system (to limit
contamination with lead compounds in water running off the flashing); and
• there must be a barrier between the lead flashing and the cladding: either a plastic strip (such as
polyethylene damp course), or paint. Flashings should conform to AS/NZS 2179.1:1994, and
be compatible with the cladding (Section 2.10, LYSAGHT Roofing & Walling Installation Manual).
Materials for flashings are available in zincalume ® or colorbond ® finishes.