Turn your roof area and roofing option into an illustrative low and high price range, plus fixed costs such as edge protection and waste.
Use this estimator to sanity-check a roofing quote before you meet the roofer, or to see whether a quote sits far outside a plausible range. Pick a roofing option, enter your roof surface area in square metres and the fixed costs that do not scale with area.
How it works. Low estimate = area × low rate + fixed costs. High estimate = area × high rate + fixed costs. Choosing an option fills in the low and high rates, which you can overwrite.
Getting the area right. Use the roof surface, not the floor area. Measure the plan area of the roof including eaves and multiply by a pitch factor (about 1.08 for 22.5°, 1.10 for 25°, 1.15 for 30°), as shown in the roof area guide.
Worked example (illustrative). A 210 m² roof going from concrete tile to steel at $90–$160 per m², plus $4,500 of fixed costs: low = 210 × 90 + 4,500 = $23,400; high = 210 × 160 + 4,500 = $38,100.
Limits. The rates are illustrative ranges chosen for this site, not survey data or quotes, and include GST. Real prices depend on your city, access, roof complexity, storeys, material profile, gutters and downpipes, structural repairs, bushfire or cyclone requirements and the contractor's overheads. Always get at least three written quotes from licensed contractors.
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