Slate Roof Coverage
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.
Project specific advice on your required roof pitch, slate size and head lap is available from the Welsh Slate technical department.
Values calculated using nominal sizes and incorporating a 5mm joint gap as per BS 8000: Part 6. We recommend the addition of at least 5% wastage allowance.
|
Size (Nominal) |
Lap `(mm) |
|||||||||||||||
|
mm |
50 |
55 |
60 |
65 |
70 |
80 |
90 |
100 |
105 |
110 |
115 |
120 |
125 |
130 |
135 |
150 |
|
600 x 350 |
10.2 |
10.3 |
10.4 |
10.5 |
10.6 |
10.8 |
11.0 |
11.3 |
11.4 |
11.5 |
11.6 |
11.7 |
11.9 |
12.0 |
12.1 |
12.5 |
|
600 x 300 |
11.9 |
12.0 |
12.1 |
12.3 |
12.4 |
12.6 |
12.9 |
13.1 |
13.2 |
13.4 |
13.5 |
13.7 |
13.8 |
14.0 |
14.1 |
14.6 |
|
550 x 300 |
13.1 |
13.2 |
13.4 |
13.5 |
13.7 |
14.0 |
14.3 |
14.6 |
14.7 |
14.9 |
15.1 |
15.2 |
15.4 |
15.6 |
15.8 |
16.4 |
|
500 x 300 |
14.6 |
14.7 |
14.9 |
15.1 |
15.2 |
15.6 |
16.0 |
16.4 |
16.6 |
16.8 |
17.0 |
17.3 |
17.5 |
17.7 |
18.0 |
18.7 |
|
455 x 250 |
19.4 |
19.6 |
19.9 |
20.1 |
20.4 |
20.9 |
21.5 |
22.1 |
22.4 |
22.7 |
23.1 |
23.4 |
||||
|
400 x 250 |
22.4 |
22.7 |
23.1 |
23.4 |
23.8 |
24.5 |
25.3 |
26.1 |
||||||||
|
400 x 200 |
27.9 |
28.3 |
28.7 |
29.1 |
29.6 |
30.5 |
31.5 |
32.5 |
||||||||
|
350 x 200 |
32.5 |
33.1 |
33.6 |
34.2 |
34.8 |
36.1 |
37.5 |
39.0 |
||||||||
|
300 x 200 |
39.0 |
39.8 |
40.7 |
41.5 |
42.4 |
44.3 |
46.5 |
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For Slate Sizes or Headlaps not listed the following formulae can be used:-
Slate Coverage = 1000000mm2 divided by (((Slate Length minus headlap) divided 2) x (Slate width +5mm perp gap)
Example 500x300 mm @ 75mm headlap:-
1000000mm2/((500 - 75) / 2) x (300 + 5)
1000000mm2/(212 x 305) = 15.5
Download our Roofing Brochure for a Comprehensive Guide to Technical Requirements and Standards
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