How many slates per square metre (m2)?
The number of roof slates that are needed depends on the spanish slate size and the headlap in mm.
For example, if you are using a 600 x 300mm slate (24″ x 12″) with a headlap of 90 mm, you would need 13 slates per m2.
The following table shows the required number of slates per square metre for effective coverage:
| Quantity of Slates | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Slate Size | Lap mm | |||||||||||
| (Nominal) mm | 50 | 65 | 75 | 80 | 90 | 100 | 110 | 115 | 120 | 130 | 140 | 150 |
| 600 x 300 | 12.1 | 12.5 | 12.7 | 12.8 | 13.1 | 13.3 | 13.6 | 13.7 | 13.9 | 14.2 | 14.5 | 14.8 |
| 500 x 300 | 14.8 | 15.3 | 15.7 | 15.9 | 16.3 | 16.7 | 17.1 | 17.3 | 17.5 | 18.0 | 18.5 | 19.0 |
| 500 x 250 | 17.8 | 18.4 | 18.8 | 19.0 | 19.5 | 20.0 | 20.5 | 20.8 | 21.0 | 21.6 | 22.2 | |
| 450 x 300 | 16.7 | 17.3 | 17.8 | 18.0 | 18.5 | 19.0 | 19.6 | 19.9 | 20.2 | 20.8 | 21.5 | |
| 450 x 250 | 20.2 | 20.8 | 21.3 | 21.6 | 22.2 | 22.9 | 23.5 | 23.9 | 24.2 | 25.0 | 25.8 | |
| 450 x 230 | 21.7 | 22.6 | 23.2 | 23.5 | 24.2 | 24.8 | 25.6 | 26.0 | 26.3 | 27.2 | 28.1 | |
| 400 x 300 | 19.0 | 19.9 | 20.5 | 20.8 | 21.5 | 22.2 | 23.0 | 23.4 | 23.8 | |||
| 400 x 250 | 22.9 | 23.9 | 24.6 | 25.0 | 25.8 | 26.7 | 27.6 | 28.1 | 28.6 | |||
| 400 x 200 | 28.6 | 29.9 | 30.8 | 31.3 | 32.3 | 33.3 | 34.5 | 35.1 | 35.7 | |||
| 350 x 300 | 22.2 | 23.4 | 24.2 | 24.7 | 25.6 | 26.7 | 27.8 | |||||
| 350 x 250 | 26.7 | 28.1 | 29.1 | 29.6 | 30.8 | 32.0 | 33.3 | |||||
| 350 x 200 | 33.3 | 35.1 | 36.4 | 37.0 | 38.5 | 40.0 | 41.7 | |||||
| 320 x 220 | 33.7 | 35.7 | 37.1 | 37.9 | 39.5 | 41.3 | 43.3 | |||||
| 320 x 180 | 41.2 | 43.6 | 45.4 | 46.3 | 48.3 | 50.5 | 53.0 | |||||
| 300 x 200 | 40.0 | 42.6 | 44.4 | 45.5 | 47.6 | 50.0 | ||||||
| 300 x 150 | 53.3 | 56.7 | 59.3 | 60.6 | 63.5 | 66.7 | ||||||
