Roofing Tool
Plan a roofing project by estimating sloped roof area, material packs, underlay rolls and ridge caps. Compare covering choices, enter waste and local pricing, and review labour, contingency, tax and an itemised cost breakdown.
| Item | Quantity | Unit price | Cost |
|---|---|---|---|
| Estimated total | — | ||
Table of Contents
Highlights
- Supports gable, hip, single-slope and flat roof shapes
- Live roof illustration responds to shape and pitch
- Estimates covering packs, underlay rolls and ridge caps
- Itemised costs with labour, contingency and tax
- Interactive cost breakdown with CSV, JSON and PNG exports
How Roofing Tool Works?
Roof measurements start with the building length L, width W and eave overhang O. The overhang is added on both ends of each dimension. The resulting rectangular plan area is adjusted for the slope of a gable, hip or single-slope roof; a flat roof uses a pitch factor of one.
For a rise-per-12 pitch, the slope ratio is rise divided by 12; for an angle entered in degrees, the ratio is the tangent of that angle. The multiplier is the hypotenuse of a right triangle with horizontal run one.
The waste percentage increases the ordering area, which is divided by the selected covering's pack coverage or underlay roll coverage. Both quantities are rounded up to whole packages.
Ridge length is estimated as the overhang-adjusted building length for gable roofs, the greater of zero and adjusted length minus adjusted width for hip roofs, and zero for single-slope and flat roofs. Ridge cap pack quantities are rounded up in the same way. Labour cost uses actual roof area, not waste-adjusted area.
| Cost component | Calculation |
|---|---|
| Covering, underlay and ridge | Whole packs or rolls × their entered prices |
| Labour | Actual roof area × labour rate per ft² or m² |
| Subtotal | Materials + labour + other fixed costs |
| Contingency | Subtotal × contingency percentage |
| Tax | (Subtotal + contingency) × tax percentage |
| Total | Subtotal + contingency + tax |
The result includes total estimated cost, cost per unit of actual roof area, quantities and an itemised table. The cost doughnut chart displays covering, underlay, ridge, labour, other costs, contingency and tax.
Practical Use Cases
Homeowners: Budget for a gable-roof replacement by entering roof dimensions, pitch, material prices and a contingency for unforeseen expenses.
Roofing contractors: Prepare an early-stage material and labour estimate, check whole-pack ordering quantities and export an itemised CSV for further review.
Builders and project managers: Compare the approximate project costs of asphalt shingles, metal panels, tiles and membranes by adjusting the preset coverage and price assumptions.
Property managers: Assess indicative reroofing allowances across properties, including other fixed costs, tax and a separately visible labour component.
DIY renovators: Estimate how many covering packs and underlay rolls a straightforward roof might require before asking suppliers to confirm specifications.
Accuracy and Limitations
Results are planning estimates based on a rectangular footprint, uniform pitch and user-entered prices and coverage. Overhang is applied to all four sides, and the same waste allowance is applied to covering and underlay. Hip ridge length is a simplified approximation; gables, valleys, dormers, penetrations, complex intersections, flashing, gutters and structural work are not individually measured. Quantities round up to whole packs or rolls, potentially increasing costs. Material presets are illustrative, not supplier specifications, and the roof drawing is schematic rather than to scale. Tax applies to subtotal plus contingency; actual installation costs and tax treatment may differ.
