Minimum Recommended Headlap B.S.5534 for nail fixing.

Notes:
A) The recommendation for laps given might not be adequate at roof pitches of less than 30 Degrees or less under the following conditions:
(i)In driving rain exposures of less than 56.5 l/m2 per spell for rafter lengths greater than 9m
(ii) In driving rain exposures of 56.5 l/m2 per spell or greater for rafter lengths greater than 6m in these circumstances please consult our technical department.

B)Where abnormal weather conditions might be expected - eg; on elevated sites near the coast, in localities where heavy snow falls are commonly experienced or in conditions of severe exposure, the recommendations for lap will not always ensure full protection. The specifier should seek guidance from a competent person conversant with local conditions.

Fixing:Stoneleaf natural slates should be fixed in accordance with BS5534.
To achieve a neat and attractive finish, the company recommends the following:

• Mark out the slate joints on the batten, allow for 5mm gap between slates to allow for free drainage. We recommend that marks are made at least every third course.
• Each slate is to be fixed to treated softwood batten, size 50x25mm, with either 2 copper nails. 3.35mm diameter; nails should be of sufficient length to penetrate the batten by 15mm or stainless steel slate hooks nail type.
• Slates are split by hand and are subject to a variance in thickness. It is imperative that the slates, prior to fixing, are sorted out into at least three or four thicknesses.

The thickest slate used at eaves level, progressing to the thinnest slate at the top of the roof. Slates of the same thickness should be used in the same course. A small percentage of slates may be twisted, (more if Standard grade slate is used). These slates should not be fixed as they are likely to "kick up", however they can be cut down and used as an under-eave slate.

Roofing contractors who wish to obtain a more comprehensive step by step fitting procedure should contact our technical department.