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

                 

 

For Slate Sizes or Headlaps not listed the following formulae can be used:-

Batten Gauge 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

Sales Office
Penrhyn Quarry
Bethesda
Bangor
Gwynedd
LL57 4YG

+44 (0) 1248 600656
enquiries@welshslate.com

Download this Roofing Brochure for a Comprehensive Guide to the Technical Requirements and Standards

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