Homeowner Professional

Here you will find the weight for the most common slate sizes and thickness.

How much does slate weigh?

Slate Coverage

To calculate the weight per per m2, we must first know how many slates  the roof will require. This table explains the required measurements for effective coverage. 

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.
Slate Coverage
Slate SizeLap mm
(Nominal) mm5065758090100110115120130140150
600 x 30012.112.512.712.813.113.313.613.713.914.214.514.8
500 x 30014.815.315.715.916.316.717.117.317.518.018.519.0
500 x 25017.818.418.819.019.520.020.520.821.021.622.2
450 x 30016.717.317.818.018.519.019.619.920.220.821.5
400 x 25020.220.821.321.622.222.923.523.924.225.025.8
450 x 23021.722.623.223.524.224.825.626.026.327.228.1
400 x 30019.019.920.520.821.522.223.023.423.8
400 x 25022.923.924.625.025.826.727.628.128.6
400 x 20028.629.930.831.332.333.334.535.135.7
350 x 30022.223.424.224.725.626.727.8
350 x 25026.728.129.129.630.832.033.3
350 x 20033.335.136.437.038.540.041.7
320 x 22033.735.737.137.939.541.343.3
320 x 18041.243.645.446.348.350.553.0
300 x 20040.042.644.445.547.650.0
300 x 15053.356.759.360.663.566.7

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.

The most common format used in the UK is 500x250mm with a thickness of 5mm and weighs approximately 35kg per m2. This is significantly less than other roofing products like concrete or clay tiles.

slate weight

Weight per slate in kilogrammes

In this table you can find the weights for the most common slate sizes and formats.

Weight per slate in Kilogrammes
Slate sizeThickness
(Nominal) mm4-5mm6-7mm
600 x 3002.4953.899
500 x 3002.4163.290
500 x 2501.8892.760
460 x 2201.2661.848
400 x 3001.7842.690
400 x 2001.0981.809
350 x 2000.9101.675
300 x 2000.8961.138

Follow Us