Metal Roof Calculator (Australia)
Estimate Colorbond and Zincalume roof sheet count, flashings, and installed cost in AUD. Trimdek, Klip-Lok, Custom Orb — sized to AS 1562 and AS 4040.
Metal Roof Calculator
Estimate panel count, trim lengths, fasteners, and installed cost for a metal roof. Pricing is matched to your locale's currency and contractor rates.
Material takeoff
- 76 panels × 5.5 m
- Ridge cap: 15 m
- Eave trim: 30 m
- Rake trim: 20.2 m
- Fasteners: 1631 (7 boxes of 250)
Cost breakdown
- Panels: $11,351
- Trim + flashing: $1,078
- Underlayment: $1,076
- Fasteners: $319
- Labour: $11,431
- Tear-off: $2,601
- Disposal: $1,345
- Permit + overhead: $730
Estimate excludes structural reinforcement, decking replacement, snow guards, gutter work, and complex flashings (chimneys, skylights). Add 5–10% contingency for cuts, valleys, and waste on hipped roofs.
What this metal roof calculator estimates
Plug in your building footprint, pitch, profile, and BMT — the calculator returns:
- Slope-adjusted roof area in m² for both planes
- Sheet count and length sized to Lysaght / Stratco profile cover widths
- Flashing takeoff — ridge capping, barge capping, valley iron, gutter board in lineal metres
- Fixings — ~3 fasteners per m² for concealed-fix, 5–6 per m² for exposed-fix
- Sarking / blanket area for AS 4200.1 underlay
- Installed cost in AUD — sheets, flashings, sarking, fixings, labour, strip-off, and skip
Pricing is anchored to BlueScope and Stratco 2026 trade rates, hipages and ServiceSeeking 2026 quote medians, and Master Builders Australia regional cost surveys. Standard cost figures are for capital city metro areas in non-cyclonic regions (AS 1170.2 wind region A or B).
Step 1 — Measure the footprint
Use the building plan dimensions, not the roof area — the calculator handles slope conversion.
- Length along the ridge direction
- Width across the rake direction (eave-to-eave on a duo-pitch)
- Add the eaves overhang on every side (typical 450–600 mm in Australia, 750 mm+ for passive solar design)
Aussie eaves overhangs are larger than UK or US standard, so factor 8–15% extra material on a typical project.
Step 2 — Pick the right profile
| Profile | Cover width | Minimum pitch | Cost (AUD, 2026) | Best for |
|---|---|---|---|---|
| Custom Orb (corrugated) | 762 mm | 5° | $90–$130 / m² | Heritage replacement, sheds, traditional Queenslanders |
| Trimdek | 762 mm | 2° | $110–$150 / m² | Standard residential, low-pitch homes |
| Klip-Lok 700 Hi-Strength | 700 mm | 1° | $130–$180 / m² | Concealed-fix premium, no exposed screws |
| Spandek | 700 mm | 3° | $130–$170 / m² | Architectural ribbed look |
| Longline 305 (Stratco) | 305 mm | 1° | $160–$220 / m² | Premium standing-seam, modern architecture |
Custom Orb is the iconic Aussie corrugated profile — same shape since the 1850s, used on every shearing shed, Queenslander, and outback homestead. Cheapest material, fastest install with exposed Type 17 screws and EPDM washers.
Trimdek is the volume residential profile in Australia. Five flat ribs at 195 mm centres, 762 mm cover. Lower minimum pitch than Custom Orb, cleaner aesthetic, similar install speed.
Klip-Lok 700 is the concealed-fix premium standard. Clip-fixed (no exposed fasteners), 1° minimum pitch, used on most low-slope additions, alfresco extensions, and architectural homes. Pairs perfectly with solar — Lysaght-approved S-5 clamps fix to the seam without piercing the sheet.
Spandek sits between Trimdek and Klip-Lok — wider flat pans, hidden-fix at the rib top, modern look at a mid-tier price.
Step 3 — Colorbond colour and warranty class
BlueScope’s Colorbond steel comes in 22 standard colours plus the Matt range. Warranty class depends on location:
- Benign environment (>1 km from breaking surf, no industrial pollutants) — full 30-year perforation warranty on Colorbond
- Industrial (within 1 km of heavy industry) — specify Colorbond Stainless or Colorbond Ultra
- Marine (within 200 m of breaking surf) — specify Colorbond Ultra (zinc-aluminium-magnesium coating, AM150 grade)
- Severe marine (within 100 m of breaking surf, regular salt-spray exposure) — Colorbond is excluded from warranty; specify aluminium or stainless steel
The BlueScope environmental classification map (available from BlueScope Steel Direct) gives the warranty class for any Australian address — always check before specifying for coastal projects.
Step 4 — Wind region and structural fixings
AS 1170.2 splits Australia into wind regions A, B, C, and D. Cyclonic regions C (north of Carnarvon WA, north of Bowen QLD) and D (offshore territories) require:
- 0.48 BMT minimum sheet thickness
- Structural battens to AS 4055 cyclonic classification
- Cyclonic-rated fasteners with thread engagement testing
- Cyclone washers under every fastener
- Sheet end-fixing every pan in the windward end-bay
The calculator sizes fasteners assuming 0.42 BMT residential and non-cyclonic — for region C/D projects, multiply fastener counts by 1.5 and step up to 0.48 BMT pricing.
Step 5 — Strip-off, sarking, and battens
Strip-off (replacing existing tiles or sheet): typical Sydney/Melbourne quote runs $25–$40 per m² for tile strip-off including skip and disposal at C&D recycling. Asbestos cement sheet (pre-1987 builds) requires a licensed Class B asbestos removalist — adds $50–$80 per m² and 2–3 days.
Sarking: AS 4200.1 mandates Class 4 sarking for sheet metal roofs. Bradford Anticon 60 or 75 is the volume product (foil-faced glasswool). Reflective foil-only sarking (Kingspan AIR-CELL Insulbreak) is acceptable in mild climate zones (NCC zones 2, 5).
Insulation: NCC 2022 Volume 2 requires R5.1 minimum total ceiling/roof R-value in cool-temperate zones (climate zones 6, 7, 8). Most retrofit jobs install R4.0 batts in the ceiling cavity plus the sarking blanket, hitting R5.1 with thermal bridging.
Battens: 40 × 19 mm hardwood or steel top-hat battens at 1100 mm centres for Custom Orb, 900 mm for Trimdek, 1500 mm for Klip-Lok (longer span allowed under structural-grade decking).
Step 6 — Flashings, ridge, and gutters
A complete metal roof flashing kit:
- Ridge capping along the full ridge length
- Barge capping on every gable end (4 × slope length on a duo-pitch)
- Valley iron at every internal valley
- Box gutters and parapet flashings if applicable
- Apron flashings at chimneys and walls
- Gutter and downpipe — typically replaced with the roof on a re-roof job, $50–$80 per lineal metre installed
Budget 12–18% of the sheet cost for flashings on a typical job. Hipped roofs sit at the high end.
Step 7 — Cost benchmarks (capital city metros, 2026)
For a 200 m² single-storey duo-pitch home (typical Aussie 4-bedder):
| Specification | Installed total | Per m² | Notes |
|---|---|---|---|
| 0.42 BMT Custom Orb on existing battens | $18,000 – $26,000 | $90 – $130 | Like-for-like replacement |
| 0.42 BMT Trimdek with new sarking | $22,000 – $30,000 | $110 – $150 | Volume residential standard |
| 0.42 BMT Klip-Lok 700 Hi-Strength | $26,000 – $36,000 | $130 – $180 | Premium concealed-fix |
| 0.48 BMT Trimdek (cyclonic, region C) | $32,000 – $44,000 | $160 – $220 | North QLD / WA cyclonic spec |
| Solar-ready Klip-Lok with S-5 clamps | $30,000 – $40,000 | $150 – $200 | Future-proofed for solar |
Add tile strip-off: $5,000 – $8,000 for a 200 m² roof. Asbestos strip-off: $10,000 – $16,000 plus EPA disposal fees.
Solar pairing — design notes
If you’re planning to add solar PV, specify:
- Klip-Lok 700, Spandek, or Longline 305 — concealed-fix profiles let you mount panels with S-5 PV clamps that pinch the standing rib without penetrating the sheet
- Avoid Custom Orb and Trimdek for solar — exposed-fix profiles need either tile-bracket-style mounts that pierce the sheet (warranty-voiding on most installs) or external rail systems that add $300–$500 per kW
A Klip-Lok roof and S-5 clamps add ~$1,500 – $2,500 to the roof cost but save $2,000 – $4,000 when you add solar later. Net win on any home where solar is planned.
Common Aussie mistakes this calculator avoids
- Using building footprint as roof area — Aussie eaves overhangs are deep (450–750 mm), so the actual roof footprint is 8–15% larger than the wall footprint.
- Specifying 0.42 BMT in cyclonic regions — invalid for AS 4055 N4–C4 wind classifications; 0.48 BMT minimum.
- Forgetting box-gutter pricing — box gutters and parapet flashings add $80–$160 per lineal metre on parapet wall homes.
- Skipping AS 4200.1 sarking — building surveyors and warranty insurers will fail the work.
- Quoting Colorbond standard on coastal sites — Ultra-grade is mandatory within 200 m of breaking surf.
For the cost-only comparison, see the metal roof cost calculator. Use the roof pitch calculator to convert from degrees to 1-in-X.
Sources
BlueScope Steel Lifetime Domestic Warranty Statement (2024 edition); Lysaght and Stratco Profile Selector Guides 2026; AS 1562.1 (Design and installation of sheet roof and wall cladding — Metal); AS 1170.2 (Wind actions); AS 4055 (Wind loads for housing); AS 4200.1 (Pliable building membranes — Materials); NCC 2022 Volume 2 Part 3.5; Master Builders Australia 2026 Residential Construction Cost Survey; hipages and ServiceSeeking 2026 quote medians.