Roof calculator — area and tile count

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.

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.

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.

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%.

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.

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.

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).

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.

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.

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.