Step flashing systems — aluminium

Capral Aluminium is Australia's largest aluminium extrusion and rolling company and a primary source for aluminium sheet used in site-formed step and soaker flashing applications. Aluminium sheet for roofing flashing is available in mill-finish (natural silver) and various alloy specifications. The flashing material is cut and site-formed by the licensed roof plumber using a brake press or hand folder to match the required step profile and tile gauge. Mill-finish aluminium is paintable on site using a compatible metal primer and topcoat, allowing the flashing to be finished to match the existing roof colour or as specified by the strata committee. Aluminium is lighter than Colorbond steel and does not require a factory-painted coating — it relies on its natural oxide layer for corrosion resistance in standard residential environments. Dissimilar metal contact must be managed carefully: aluminium in direct contact with copper, lead, or copper-contaminated runoff will experience galvanic corrosion. Where copper roof elements or copper pipe penetrations are present, isolate the aluminium flashing with a non-absorbent separator tape or sleeve. Confirm minimum thickness, alloy specification, and fixing requirements with Capral and AS 1562.1 before ordering for roofing applications.

Metalcorp Group is a major Australian steel and metals distributor providing aluminium sheet as an alternative supply channel to Capral for site-formed step and soaker flashing. Metalcorp carries aluminium sheet in a range of thicknesses and alloys from national distribution centres and regional branches, making it a practical supply option for roof plumbers working in areas where Capral direct supply may not be available or competitive. The forming method, AS 1562.1 compliance requirements, dissimilar metal precautions, and painting requirements for Metalcorp aluminium sheet are identical to Capral — the material is aluminium sheet regardless of the supply source. Confirm the specific alloy, temper, and thickness with Metalcorp before ordering for roofing flashing applications — not all aluminium sheet alloys and tempers are equally suitable for brake pressing and field forming. The 3003 alloy (common aluminium sheet alloy) is generally suitable for formed flashing applications — confirm with Metalcorp technical before ordering.

Where a standard aluminium sheet supply and site-forming process does not suit the project — for example, where the tile gauge is non-standard, the wall profile requires a complex step profile, or a large volume of pre-formed flashings is required for a major strata building remediation — a custom aluminium fabricator can supply pre-formed step and soaker flashings to a specific profile and dimension. Custom fabrication allows the flashing to be formed in a factory environment to a tighter dimensional tolerance than site-forming, and pre-painted or powder-coated finishes can be specified to match or complement the existing roof colour without site painting. The fabricator will require a profile drawing or site dimension for each flashing type — step height, upstand length, soaker length, and any special bends. AS 1562.1 minimum dimensions still apply — the fabricator must be briefed on the standard requirements before fabrication. Lead time, minimum order quantity, and finish options vary by fabricator — confirm all with the selected fabricator before specifying. For standard residential remediation with a small number of flashings, site-forming from Capral or Metalcorp sheet is usually more practical than custom fabrication.