Slate Coverage, Roof Pitch & Lap

Use this Slate Coverage chart to assist in calculating your required slate quantity.

The table below shows Slate coverage by number per m²
Size - Nominal (mm) 50mm Lap 65mm Lap 75mm Lap 80mm Lap 85mm Lap 90mm Lap 95mm Lap 100mm Lap 105mm Lap 110mm Lap 115mm Lap 120mm Lap 125mm Lap 130mm Lap 135mm Lap 140mm Lap 145mm Lap 150mm Lap 155mm Lap
600 x 300
11.9
12.3
12.5
12.6
12.7
12.9
13.0
13.1
13.2
13.4
13.4
13.5
13.8
14.0
14.1
14.3
14.4
14.6
14.7
500 x 300
14.6
15.1
15.4
15.6
15.8
16
16.2
16.4
16.6
16.8
17
17.3
17.5
17.7
18.0
18.2
18.5
18.7
19.0
500 x 250
17.4
18.0
18.5
18.7
18.9
19.1
19.4
19.6
19.9
20.1
20.4
20.6
20.9
21.2
21.5
21.8
22.1
22.4
22.7
460 x 225
16.4
17.0
17.5
17.7
18.0
18.2
18.5
18.7
19.0
19.3
19.6
19.9
20.2
20.5
20.8
21.2
21.9
21.9
-
400 x 250
22.4
23.4
24.1
24.5
24.9
25.3
25.7
26.1
26.6
27.0
27.5
28.0
28.5
29.0
-
-
-
-
-
400 x 200
27.9
29.1
30.1
30.5
31.0
31.5
32.0
32.5
33.1
33.6
34.2
34.8
35.5
36.1
-
-
-
-
-
350 x 250
26.1
27.5
28.5
29.0
29.6
30.2
30.9
31.4
32.7
32.7
33.4
-
-
-
-
-
-
-
-
350 x 200
32.5
34.2
35.5
36.1
36.8
37.5
38.3
39.0
39.8
40.7
41.5
-
-
-
-
-
-
-
-
300 x 200
39.0
41.5
43.4
44.3
45.4
46.5
47.6
48.8
-
-
-
-
-
-
-
-
-
-
-

Values calculated using nominal sizes and incorporating a 5mm joint gap as per BS8000: part 6: 1990. We recommended the addition of at least 5% wastage allowance.

Slate Coverage & Cost

The actual cost of a roof per unit floor area of the building is determined by a number of factors, including roof pitch, slate size and head lap. By taking advantage of the various sizes and types of SlateScape roofing slate, considerable cost savings can be made.

 

Roof Pitch & Lap

The shallower the roof pitch, the smaller the area of the roof slopes. This area reduction, however, does not automatically lead to a cost reduction because lower pitches require larger slates and laps. The full cost advantage can be taken by adjusting the lap to the minimum required, for the pitch of the roof.