Opens our free tool — no signup, no email required.
What this designer does
Start with a preset profile (corner mould, J-flashing, barge, vermin, ridge cap) or sketch your own from scratch. Drag bends, click any number to edit it, pick Colorbond or Zincalume, choose which face the colour goes on. The designer adds up the girth so you know what stock width to order. When you're done, save the design and send it to us — we'll quote rolling it in your colour and material. Free to use, free to send.
Flashings, in plain language
A flashing is a strip of folded sheet metal that closes a gap. Every shed and patio has a dozen of them — ridge caps where the two roof slopes meet, barge flashings where the roof finishes at the gable end, valley gutters where two roofs join, corner moulds on the walls, J-flashings around windows. They're the bit that keeps the rain out of the joins.
Two numbers matter when you're ordering a custom flashing: the girth (how wide the flat sheet has to be before you fold it) and the bend angles (the geometry of the folds). A flashing with four segments at 50 mm, 150 mm, 150 mm, 50 mm has a girth of 400 mm — meaning we fold it from a 400 mm wide flat strip. Get the girth wrong and the flashing won't sit right; get the bend angles wrong and it won't sit flat on the roof or wall.
The designer is built to take the maths out of it. Draw what you need, drag the bends, type the segment lengths. The girth updates live. The 2D preview shows you how it'll look folded, and a colour overlay shows which face will be the outside (the bit you see from the ground) once it's on the roof.
Worked example
Profile: default ridge cap — 4 segments of 50 mm / 150 mm / 150 mm / 50 mm with 110° / 140° / 110° bends.
Material: Colorbond, 0.55 mm thickness, Surfmist on the outside face.
Result: girth 400 mm. Order a 400 mm flat strip in Surfmist 0.55 mm Colorbond and we can roll it to length. Standard lengths run to 8 m; longer runs are joined with overlaps. Cut-to-length is per linear metre with a small setup fee per bend setup.
FAQ
What's the difference between standard and custom flashings?
Standard flashings (ridge cap, barge, J-flashing, etc.) are roll-formed in bulk at the mill in fixed profiles. You order by linear metre. Custom flashings are folded one-off to your exact profile — same material, but the geometry matches your specific job. Custom costs a bit more per metre because of the setup, but it's the only option when the standard profiles don't fit.
What thickness should I pick?
0.55 mm is the standard for Colorbond cladding and most flashings — matches the sheets, sits flat, takes a bend cleanly. 0.40 mm is thinner and cheaper, used for light-duty internal trims and where you're going to be hand-folding on site. 0.80 mm is heavy gauge for industrial flashings and barge cappings on big spans where wind uplift is a concern.
Why does the colour side matter?
Colorbond is painted on one face only — the other face is the backing colour (typically off-white or grey). When you fold the sheet, the painted side ends up either on the outside (visible from the ground) or the inside (against the building). The designer lets you flip the colour to whichever face you want it on. For a ridge cap, you want the colour on the outside. For a gutter, the colour is usually on the inside.
What's the maximum length you can roll?
Standard maximum is 8 m per piece. Longer flashings are joined with a sealed overlap (usually 100 mm overlap, sealed with neutral-cure silicone). Most jobs are well under 8 m anyway — a 9 m × 6 m shed has a ridge cap of about 9 m, which is typically two 5 m sections with one overlap.
What Colorbond colours can I get?
All 22 standard Colorbond colours from BlueScope — Surfmist, Monument, Woodland Grey, Basalt, Dune, Shale Grey, Ironstone, Manor Red, and the rest. Stock varies by colour; common ones (Surfmist, Monument, Woodland Grey) are usually on the shelf, less-common shades may be a few days' lead time from BlueScope.
How do I send a design to you?
From inside the designer, click Save this design. You'll be prompted for your contact details and a description of the job (lengths, quantities, where it's going). We get an email with your design attached, including the girth, bend angles, and segment lengths. Quote usually comes back within one business day.
Need flashings rolled?
Design as many as you want here — free, no obligation. When you're ready to order, hit Save this design inside the tool and we'll quote rolling it in your colour and material. If you need flashings as part of a bigger shed or patio job, we can handle the whole thing — slab, frame, sheets, flashings, the lot. 25-year warranty on every build.