Roof Material Calculator — Tiles, Underlay, Battens & Ridge
Calculate the complete material list for a pitched roof: tiles or shingles, underlay, battens, ridge units and fixings. Enter the roof footprint and pitch, and get true roof area with every component counted.
Save to project
Free to try — no sign-up
Plan the whole job — not just this calculation
Save results to a project: budget and shopping list build themselves, and the whole plan exports as a PDF. Draw your floor plan and room sizes pre-fill the calculators.
How the roof material list is calculated
- 1Plan area = footprint length × width; true roof area = plan area ÷ cos(pitch)
- 2Tiles: roof area × tiles per m² (from the product data), plus 10% cutting waste
- 3Underlay: roof area + 15% for overlaps
- 4Battens: roof width × number of tile rows (row count = slope length ÷ batten gauge)
- 5Ridge: ridge length ÷ ridge unit cover, plus hip lengths on hip roofs
- 6Fixings: clips/nails per tile per the exposure zone requirement
Worked example
Gable roof: 8 × 6 m plan, 30° pitch. Concrete interlocking tiles at 10 per m², 320 mm batten gauge.
True roof area: 48 ÷ cos(30°) = 55.4 m². Materials: 610 tiles (10% waste), 64 m² underlay, ~176 lm battens (11 rows per side), 8 m of ridge units.
Frequently asked questions
What materials make up a tiled roof?
From the rafters out: underlay membrane, counter-battens (on some systems), tile battens, the tiles themselves, ridge and hip units, verge/eave closures, and fixings. Flashings around chimneys and valleys are separate items.
How do I calculate roof material from ground measurements?
Measure the building footprint, then multiply by the pitch factor: 25° = 1.10, 30° = 1.15, 35° = 1.22, 45° = 1.41. That converts plan area to the true sloped area every material is bought against.
How much underlay do I need for a roof?
True roof area plus about 15% for the horizontal laps (typically 100–150 mm per course) and eaves/ridge details. A 55 m² roof needs roughly 64 m² of membrane.
How many battens do I need?
Rows per side = slope length ÷ batten gauge (the gauge comes from the tile — commonly 320–345 mm for interlocking tiles). Total = rows × roof width × 2 sides. Order in long lengths to minimise joints.
Does the calculator handle metal roofing?
Yes — choose the steel sheet covering and it prices the roof per m² of coverage, with sheet-support battens at 600 mm centres, sealing-washer screws (~8 per m²) and steel ridge caps. See the dedicated metal roof calculator page for panel-specific guidance.