Direct Contact Between Metals

Contact with (or run-off from) some materials can damage coated steel products. The materials include certain metals, treated timbers and chemicals. As a consequence:

  • Don’t allow any contact of coated steel products with incompatible materials. (See table DD DCM A 001)
  • Don’t allow discharge of rainwater from incompatible materials onto coated steel products. (See table DD DCM AD 001)
  • Ensure that supporting members are compatible with the coated steel products or alternatively are appropriately coated.

If there are doubts about the compatibility of other products being used, seek advice from your nearest Fielders Branch. 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)
  • any material which will inhibit normal exposure to the atmosphere

Compatibility of Direct Contact Between Metals

Roof Drainage System Components and any Cladding MaterialAccessory or Fastener Material
ZINCALUME® SteelGalvanised SteelZincCOLORBOND® Steel (Plus Ultra, Metallic & Matt)COLORBOND® Stainless SteelStainless Steel (300 series)Aluminium AlloysCopper and Copper Alloys*Lead2
Atmospheric classification
SI and VSMildSI and VSMildSI and VSMildSI and VSMildSI and VSMildSI and VSMildSI and VSMildSI and VSMildSI and VSMild
Aluminium AlloysNo4No4No4No4No4No4No4No4No4No4Yes3Yes3YesYesNoNoNoNo
ZINCALUME® SteelYesYesYes1Yes1Yes1Yes1YesYesNoYesNoYesYesYesNoNoNoNo
Galvanised SteelYesYesYesYesYesYesYesYesNoYesNoYesYesYesNoNoNoYes
ZincYesYesYesYesYesYesYesYesNoYesNoYesYesYesNoNoNoYes
COLORBOND® Steel (Plus Ultra, Metallic & Matt)YesYesYes1Yes1Yes1Yes1YesYesNoYesNoYesYesYesNoNoNoNo
COLORBOND® Stainless SteelNoNoNoNoNoNoNoNoYesYesYesYesNoNoNoNoNoNo
Stainless Steel (300 series)NoNoNoNoNoNoNoNoYesYesYesYesNoNoNoNoNoYes
Copper and Copper AlloysNoNoNoNoNoNoNoNoNoYesNoYesNoNoYesYesNoYes
Lead2NoNoNoYesNoYesNoNoYesYesYesYesNoNoYesYesYesYes
Table DCM C 001

Legend:

SI, VS, Mild = Severe industrial, very severe and mild classifications (see AS/NZS 2312).

Yes = Acceptable - as a result of bimetallic contact, either no additional corrosion of rainwater goods will take place, or at the worst, only very slight additional corrosion. It also implies that the degree of corrosion would not significantly shorten the service life.

No = Not acceptable - moderate to severe corrosion of rainwater goods will occur, a condition which may result in a significant reduction in the service life.

Note:
  1. Unpainted zinc-coated steel and zinc are suitable for direct contact but should not receive drainage from an inert catchment.
  2. Due to its toxicity, lead is not recommended for rainwater goods.
  3. Fixings only.
  4. Our experience is that these materials are not compatible in corrosive environments so our advise differs from AS/NZS 3500.3:2015 Table 4.4.1

Compatibility of Drainage from an Upper Surface to a Lower Metal Surface

Lower Roof Drainage System MaterialUpper Cladding or Roof Drainage System Material
ZINCALUME® SteelGalvanised SteelZincCOLORBOND® Steel (Plus Ultra, Metallic & Matt)COLORBOND® Stainless SteelStainless Steel (300 series)Aluminium AlloysCopper and Copper AlloysLead2Glazed Roof Tiles, Glass and Plastic
Aluminium AlloysNo4No4YesNo4Yes5Yes5YesNoNo4Yes
ZINCALUME® SteelYesYesYesYesYes5Yes5YesNoNoYes
Galvanised Steel4NoYesYesNoNoNoNoNoYes5No
ZincNoYesYesNoNoNoNoNoYes5No
COLORBOND® Steel (Plus Ultra, Metallic & Matt)YesYesYesYesYes5Yes5YesNoNoYes
COLORBOND® Stainless SteelYes5Yes5Yes5Yes5YesYesYes5Yes5YesYes
Stainless Steel (300 series)Yes5Yes5Yes5Yes5YesYesYes5Yes5YesYes
Copper and Copper AlloysYes5Yes5Yes5Yes5Yes5Yes5Yes5YesYesYes
Lead2Yes5Yes5Yes5Yes5Yes5Yes5Yes5Yes5YesYes
Table DCM AD 001

Legend:

Yes = Acceptable - as a result of bimetallic contact, either no additional corrosion of rainwater goods will take place, or at the worst, only very slight additional corrosion. It also implies that the degree of corrosion would not significantly shorten the service life.

No = Not acceptable - moderate to severe corrosion of rainwater goods will occur, a condition which may result in a significant reduction in the service life.

Note:
  1. Unpainted zinc-coated steel and zinc are suitable for direct contact but should not receive drainage from an inert catchment.
  2. Due to its toxicity, lead is not recommended for rainwater goods.
  3. Fixings only.
  4. Our experience is that these materials are not compatible in corrosive environments so our advise differs from AS/NZS 3500.3:2015 Table 4.4.1
  5. Although drainage between the materials shown would be acceptable, direct material contact should be avoided.