Technical Information

Installation Details

Sorting slates

We recommend that the slates are sorted into at least three grades of thickness. It is extremely important that slates are sorted prior to fixing to ensure that slates in any one course are of the same thickness to prevent "kicking" slates or unsightly gaps. Whilst grading it is very important to tap each slate to ensure it is sound.

Fixing slates

Any slating work should be in accordance with the latest editions of BS5534 Part 1: 1997 and BS 8000: part 6 or with any subsequent parts/editions or standards

We advise that slate and halves be used where cutting of normal slates would result in slates with widths being narrower less than 150mm (6") reducing the side lap and therefore the integrity of the roof.

Nails should comply with BS 1202: Part 2 Copper clout minimum shank diameter 3.35mm. Nails should be of adequate length to ensure 20 mm of penetration into the batten. The type of shank on the nail will depend on site exposure.

Hook Fixing is a common practice in Europe and suitable for all natural roofing slate. We would recommend that only this method of fixing is used for all Brazilian slates.

Map showing the country divided into two zones on basis of wind speeds

Batten size

50 x 25mm for double lap slates with minimum 450 mm span recommended.

Scottish Practice

Traditional Method

As above

Fixing

It is generally recognised that single head nailing is acceptable with small slates, but every third course should be double nailed.

 

Boarded Roofs
  
 
Minimum Recommended Headlap
Slate Size
Moderate Exposure
Severe Exposure
Roof Pitch
Roof Pitch
mm
inches
20
22.5
25
27.5
30
35
40
45
22.5
25
27.5
30
35
40
45
600 x 300
24 x 12
-
-
95
85
80
70
60
55
-
-
-
100
90
80
70
500 x 300
20 x 12
115
105
95
85
80
70
60
55
130
120
110
100
90
80
70
500 x 250
20 x 10
-
-
95
85
80
70
60
55
-
-
110
100
90
80
70
400 x 250
16 x 10
-
-
-
-
80
70
60
55
-
-
-
100
90
80
70
400 x 200
16 x 8
-
-
-
-
80
70
60
55
-
-
-
100
90
80
70
 
Weight/Coverage
Slate Size
Weight
Slates per m2
Lap (mm)
mm
inches
per 1000
50
65
75
80
85
90
95
100
105
110
115
120
130
600 x 300
24 x 12
3000kg
12.1
12.5
12.7
12.8
12.9
13.1
12.2
13.3
13.5
13.6
13.7
13.9
14.2
500 x 300
20 x 10
2400kg
14.8
15.3
15.7
15.8
16.0
16.2
16.4
16.6
16.8
17.0
17.2
17.4
18.0
500 x 250
20 x 10
2000kg
17.8
18.4
18.8
19.0
19.3
19.5
19.8
20.0
20.3
20.5
20.8
21.1
21.6
400 x 250
16 x 10
1400kg
22.9
23.9
24.6
25.0
25.4
25.8
26.2
26.7
27.1
27.6
28.1
28.6
-
400 x 200
16 x 8
1200kg
28.5
29.6
30.7
31.2
31.7
32.1
32.6
33.2
33.7
34.2
34.8
35.4
-
 

Natural slates are individually split and individually dressed and should be treated as an individual unit when being fixed on the roof. One slate may suit a particular location on the roof better than another, perhaps for reasons of thickness, natural curvature, surface texture of appearance, therefore proper grading and selection of slates is extremely important to achieve a neat and attractive finish.

 

All Slate will weather to a degree and after time will show a surface difference in colour tones. When the change is slight the colour is classified as "permanent" or "unfading". If the final results are more evident, the colours are classified as "weathering".

Please note all green slates may be subject to slight oxidation on the surface. This does not affect the slates integrity or performance as a roofing material or the life expectancy of the slate.