Roof calculator — area and tile count
The roof calculator computes the actual roof slope area based on pitch angle and estimates the number of tiles and batten rows needed for your project. Enter the building length, width, roof pitch and material wastage allowance to get indicative quantities for planning a new build or a roof renovation. All calculations follow standard Polish construction practice.
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How we calculate roof area
Actual slope area = length × width ÷ cos(pitch angle in radians). The formula accounts for the fact that a pitched surface is longer than its horizontal projection. We then add a wastage allowance (10–20%) for cuts, overlaps and breakage. Tile count assumes 10 tiles/m² (standard for concrete tiles). Batten rows = width ÷ 0.345 m (standard batten spacing in Poland).
Example calculation
Roof 8 × 6 m, pitch 30°, wastage 15%. Plan area: 8 × 6 = 48 m². Pitch correction: 48 ÷ cos(30°) ≈ 55.43 m². With 15% allowance: 55.43 × 1.15 ≈ 63.74 m². Tile count: 63.74 × 10 ≈ 638 pieces. Batten rows: 6 ÷ 0.345 ≈ 18 rows.
Frequently asked questions
How do I calculate roof surface area?
Roof area = length × width ÷ cos(pitch angle). For a 30° pitch roof 8 × 6 m: 48 ÷ cos(30°) ≈ 55.4 m². Add 10–15% wastage for cuts and overlaps.
How many tiles are needed per 1 m² of roof?
It depends on the tile type. Standard concrete tiles (e.g. Braas): 10–14 pcs/m². Traditional clay flat tiles: 35–40 pcs/m². The calculator uses 10 pcs/m² as a typical value for popular concrete tiles.
What is the optimal roof pitch in Poland?
The most common pitch in Poland is 30–45°. 30–35° suits most roofing materials; 40–45° is recommended for clay and concrete tiles. Pitches below 15° require special flat-roof materials such as bituminous membrane or standing-seam metal.
What is material wastage and how much should I add?
Wastage is extra material purchased beyond the calculated requirement to cover cuts, overlaps and breakage. For simple roofs add 10–12%; for complex shapes (dormers, hips, valleys) add 15–20%.
How do I calculate the number of batten rows?
Batten rows = roof width ÷ batten spacing. Standard spacing for popular tiles is 32–35 cm; the calculator uses 34.5 cm. Check the exact value in your tile manufacturer's technical sheet.
How much does a tiled roof cost in Poland?
Approximate costs: concrete tile 35–80 PLN/m², clay tile 60–150 PLN/m², glazed tile 100–250 PLN/m². Labour: 40–80 PLN/m². Battens and counter-battens: 15–30 PLN/m². Total installed cost for a 100 m² roof: roughly 15,000–35,000 PLN.
What roofing materials are available?
Popular options in Poland: clay tile (100+ years, heavy 40–55 kg/m²), concrete tile (30–50 years, 40–50 kg/m²), metal tile sheet (4–6 kg/m², 30–50 years), standing-seam metal (50+ years), bituminous shingles (15–30 years), torch-on membrane (flat and low-pitch roofs).
When should I replace a roof?
Signs of a failing roof: water ingress inside, cracked or missing tiles, corroded flashings at chimneys, mould or damp in the attic, or a roof over 30–40 years old depending on material. Inspect every spring and autumn.
How do I plan a roof renovation?
Step 1 — assess condition. Step 2 — design and permits (tile replacement usually needs only a building notification). Step 3 — choose materials. Step 4 — get at least 3 quotes. Step 5 — schedule work in summer dry season. Step 6 — final inspection and warranty.
Can I lay roof tiles myself?
It is technically possible but requires roofing skills, scaffolding, personal protective equipment and knowledge of batten systems. Mistakes can cause leaks and costly repairs. DIYers are advised to prepare battens themselves and hire a roofer for laying the tiles. Working at height is dangerous — always use fall protection.
Results are indicative and intended for preliminary material estimation only. Exact quantities should be confirmed by a qualified roofer or structural designer. Tile count varies by product type — always check the manufacturer's technical data sheet.