Why use a pitch factor
The actual roof area is always larger than the "footprint" area (the house area seen from above), because the roof is pitched (sloped). The pitch factor adjusts for this difference — the steeper the roof, the higher the factor. A roof with a typical 30% slope uses a factor around 1.15.
Formula
Roof area = house area × pitch factor. Tiles = roof area × tiles per m² × 1.05 (5% waste).
Tiles per m² by type
| Type | Tiles per m² (approx.) |
|---|---|
| Ceramic | ~16 tiles/m² |
| Concrete | ~10.5 tiles/m² |
Tip
These figures vary by tile model — always check the manufacturer's spec sheet for an exact calculation.
Frequently asked questions
Which pitch factor should I use?
It depends on the actual roof slope — 1.15 is a common estimate for moderate slopes (~30%); steeper roofs use a higher factor.
Why do ceramic and concrete tiles have different coverage?
Because tile dimensions and shape vary between types, changing how many fit per m².
Does this include ridge caps and eaves?
Not directly — for a full estimate, also check the quantity of complementary pieces (ridge tiles, flashing, etc.) with your supplier.
Is the 5% margin enough?
It's a standard market margin; for complex roofs with many cuts, consider a larger margin.