How Many Roof Tiles Do I Need? Per m² and for a Gable Roof (UK)
The number of tiles per square metre is 1 ÷ (batten gauge × cover width): about 61 for plain tiles and 10 for interlocking concrete tiles. A gable roof on an 8 × 6 m house at 30° has 59 m² of roof, which takes 3,929 plain tiles or 627 interlocking tiles with 10% waste, plus 589 m of batten, 21 ridge tiles and 2 rolls of underlay. The roof tile calculator does your roof, and lets you enter a tile of any size.
Tiles by house size
Gable roof at 30°, 10% waste, 150 mm eaves overhang and 50 mm verges:
| Building (ridge × eaves) | Roof area | Plain tiles | Interlocking tiles | Battens (plain) | Ridge tiles |
|---|---|---|---|---|---|
| 6 × 5 m | 37 m² | 2,489 | 397 | 373 m | 16 |
| 8 × 5 m | 50 m² | 3,305 | 527 | 496 m | 21 |
| 8 × 6 m | 59 m² | 3,929 | 627 | 589 m | 21 |
| 10 × 6 m | 73 m² | 4,899 | 781 | 735 m | 26 |
| 10 × 7 m | 85 m² | 5,676 | 905 | 851 m | 26 |
| 12 × 8 m | 116 m² | 7,732 | 1,233 | 1,160 m | 31 |
How the pitch changes the area
For an 8 × 6 m building. A steeper roof has a longer slope, so it needs more tiles:
| Pitch | Slope length | Roof area | Plain tiles | Interlocking tiles |
|---|---|---|---|---|
| 15° | 3.26 m | 52.8 m² | 3,523 | 562 |
| 20° | 3.35 m | 54.3 m² | 3,621 | 578 |
| 22.5° | 3.41 m | 55.2 m² | 3,683 | 588 |
| 25° | 3.48 m | 56.3 m² | 3,754 | 599 |
| 30° | 3.64 m | 58.9 m² | 3,929 | 627 |
| 35° | 3.85 m | 62.3 m² | 4,154 | 663 |
| 40° | 4.11 m | 66.6 m² | 4,441 | 708 |
| 45° | 4.45 m | 72.2 m² | 4,812 | 767 |
Each type of tile has a minimum pitch (plain tiles usually 35° or more, interlocking tiles often 22.5° or less), so check the maker's data sheet.
Gauge and cover
| Tile | Size | Lap | Batten gauge | Tiles per m² |
|---|---|---|---|---|
| Plain tile | 265 × 165 mm | Double lap | 100 mm | 60.6 |
| Interlocking concrete tile | 420 × 330 mm | Single lap | 345 mm | 9.7 |
The gauge is the distance between battens. For a double lap (plain tiles) it is half the length less the headlap, and for a single lap (interlocking tiles) it is the length less the headlap.
What else to order
- Battens: the roof area divided by the gauge gives the metres needed. Add 10% for cuts.
- Ridge tiles: one for every 400 mm or so of ridge, and hips and valleys are extra. Dry-fix ridge systems are quicker and avoid cracked mortar.
- Underlay: a breathable membrane in rolls of 50 m × 1 m, with overlaps and extra at the eaves.
- Fixings: nails or clips of the right type for your wind exposure, and eaves and verge trims.
- Extras: verge tiles, eaves tiles, vents and flashings, which depend on the details of your roof.
Before you order
- Measure the roof accurately, from the ridge to the eaves along the slope, and the length of the ridge. Include the overhangs.
- Ask the tile maker for the gauge, headlap and minimum pitch for your tile and your pitch.
- Check the roof structure can carry the weight of the new covering. Concrete tiles are much heavier than slate.
- Order all the tiles from the same batch, with 5 to 10% extra for cuts and spares.
- Re-roofing normally needs a competent roofer, and may need Building Regulations approval, especially for changes to the structure or insulation.
See also the loft insulation calculator. Estimates only: follow the tile maker's instructions and Building Regulations.
Frequently asked questions
How many roof tiles per square metre?
About 61 for plain tiles (265 × 165 mm at a 100 mm gauge) and 10 for interlocking concrete tiles (420 × 330 mm at a 345 mm gauge). The tile maker's gauge and cover width give the exact figure.
How many tiles for an 8 × 6 m roof?
3,929 plain tiles, or 627 interlocking tiles, for a gable roof at 30° with 10% waste: 59 m² of roof.
How do you work out the batten gauge?
For a double lap, (tile length − headlap) ÷ 2: 100 mm for a 265 mm tile with a 65 mm headlap. For a single lap, tile length − headlap: 345 mm for a 420 mm tile with a 75 mm headlap.
How much does the pitch add to the roof area?
The roof area is the plan area divided by the cosine of the pitch: the 8 × 6 m roof is 58.9 m² at 30° and 66.6 m² at 40°.
How many ridge tiles do I need?
About one for every 400 mm of ridge, so 21 for a ridge of 8.1 m.
More guides
Tools & materials for this project
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Estimates only. Quantities depend on your materials, site and supplier. Confirm important numbers before you order, and check the Building Regulations and any planning rules for anything structural or close to a boundary.