Flashings are the unsung heroes of every metal roof. Sheets keep the weather off the broad areas, but it’s the folded steel trims — ridges, barges, aprons, valleys and box gutters — that seal every junction where roofs meet walls, edges and each other. The good news: you no longer need to visit a sheet metal shop with a cardboard template. Custom flashings can now be ordered online and folded to your exact profile within days. Here’s how.
Step 1: Identify the Flashings Your Job Needs
Walk the roof (or the plans) and list every junction:
- Ridge capping — the apex where two roof planes meet.
- Barge capping — the sloping gable edges. Both are covered in detail in our barge capping and ridge capping cost guide.
- Apron flashings — where a roof runs into a vertical wall, such as below a second storey or against a parapet. See apron flashing installation for how these fit.
- Valley gutters — internal junctions between roof planes.
- Drip edges, wall cappings and box gutters — the specialty folds that finish parapets and internal drainage.
Step 2: Measure Each Fold, Not Just the Total Width
A flashing is described by its cross-section: the length of each face (fold) and the angles between them. To specify one:
- Sketch the profile end-on — a simple pencil drawing is perfect.
- Label each face length in millimetres, working around the shape in one direction.
- Note the angles — 90° is assumed unless marked; roof-pitch angles should match your roof (e.g. 22.5° for a 22.5° pitch).
- Mark which side is the colour side. Steel is coloured on one face, so the fold direction matters.
Total girth (all faces added together) drives the price — flashings are folded from flat sheet, and wider girths use more steel and larger brake presses.
Step 3: Choose Material and Colour to Match the Roof
Order flashings in the same material as your roof: Colorbond in the matching colour, or Zincalume for unpainted roofs. Standard flashing material is 0.55 BMT, which is slightly heavier than roof sheeting for crisp, straight folds. If you’re mid-project on a full roof order, add flashings to the same cart as your custom cut roofing sheets so everything arrives together and colour-matched from the same batch.
Step 4: Specify Lengths and Quantities
Flashings come in lengths up to 8 metres, but 3-metre lengths are easiest to handle and lap on site. Add 150mm of lap allowance at every join when calculating quantities. For a 12m ridge, order 4 × 3.15m rather than 4 × 3.0m and you won’t come up short.
Step 5: Order Online and Check the Confirmation Drawing
At ClickSteel, ordering works like this:
- Select the flashing type or upload your sketch.
- Enter face lengths, angles, colour and quantity.
- Review the generated profile drawing — this is your moment to catch a reversed fold or wrong angle.
- Confirm, pay, and your flashings are folded and dispatched, typically within 3–5 business days. Freight works the same as sheet delivery — our steel roofing delivery guide explains lead times by region.
Common Ordering Mistakes to Avoid
- Forgetting lap allowance — always add 150mm per join.
- Mirroring the profile — a left-hand barge is not a right-hand barge. Order both if your roof has both.
- Undersizing cover. An apron should extend at least 150mm up the wall and 100mm over the roof; skimpy flashings are the number-one cause of leaks at junctions.
- Mismatched colour batches — order flashings with your sheets, not weeks later.
Ready to Order?
Whether it’s ten standard barges or a one-off box gutter from a site sketch, custom flashings are a few clicks away. Browse roofing flashings online, or email your sketch to the ClickSteel team and we’ll quote it same day.