NATURAL SLATE
COVERAGE AND WEIGHTS
SLATE COVERAGE
This table explains the required measurements for effective coverage.
| Slate Coverage | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 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 | |
| 400 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 | ||||||
The values shown in the Slate Coverage chart above are calculated using nominal sizes and incorporate a 5mm jointing gap. We recommend the addition of at least 5% wastage allowance.
Weight per square metre
To calculate the weight per square metre, simply multiply the weight per slate given below by the number of slates per square metre for the same slate listed above.
For example; 500 x 250mm slate (4–5mm thick) = 1.889 kg x 18.8 (at 75mm lap) = 35.51kg per square metre.
Weight per Slate in Grammes
| Weight per slate in Grammes | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Slate size | Thickness | ||||||||
| (Nominal) mm | 4-5mm | 6-7mm | |||||||
| 600 x 300 | 2.495 | 3.899 | |||||||
| 500 x 300 | 2.416 | 3.290 | |||||||
| 500 x 250 | 1.889 | 2.760 | |||||||
| 460 x 220 | 1.266 | 1.848 | |||||||
| 400 x 300 | 1.784 | 2.690 | |||||||
| 400 x 200 | 1.098 | 1.809 | |||||||
| 350 x 200 | 0.910 | 1.675 | |||||||
| 300 x 200 | 0.896 | 1.138 | |||||||
