Alumaz Slate Roofing


Pitch: Recommended minimum 17°. Absolute minimum 12° (contact Mazista for specification).

Slates: Length 280mm with widths of 205mm, 225mm, 255mm, 305mm, 355mm and 405mm. Holed for top nailing, with 2 holes DRILLED NOT PUNCHED.

Colour: Silver Blue, West Country or Multi Colour

Nails: 40mm length, 2.8mm diameter,  non-corrosive nails.

Trussed Rafters: Free-standing rafters require correct calculation of size and spacing, based on an overall weight of slate roofing underlay of approximately 45kg/m2. Any tables of size and spacing of free standing rafters should be considered as a guide only.

Battens: 38mm x 38mm (nominal). Laying of Battens is to be commenced at the eaves, allowing for the correct overhand of slate into the gutter, then continued upwards towards the ridge. See diagram overleaf for spacing details. Where slates are to be fixed directly onto timber boarding, the boarding shall be at least 25mm thick.

Laying: Slates are to be laid in single thickness, with a headlap of 90mm. On a lapped underlay consisting of waterproof membrane (450mm wide) all as approved by Mazista. The lower edge of the underlay is to be kept in line with the tails of the slates laid on it, so that there is a double course of underlay, to the second batten, with a 50mm overhang into the gutter. The next roll of underlay is then laid in position, and the second course of slates is top nailed, through the underlay, to the third batten. This sequence is followed upwards towards the ridge. Slates are to be laid to straight lines horizontally and vertically, in broken bond.

Plumbing: All plumbing requirements are to be supplied by the builder. Laying of the slate roof will be delayed if a plumber is not made available, when requested by Mazista, for supplying and cutting the necessary flat iron, flashings, etc. Wall soakers to measure 150mm across, with 75mm turn-up, and length 280mm.


Construction Detail:


Top of Fascia Board to be 13mm higher than top of second batten, to allow as tilting batten.
Top of Ridge Batten to be 20mm above level of other battens.

Note 1:
Where Fascia board is not required, tilting batten 50mm x 38mm should be used instead.

Note 2:
Batten Spacings: (All slates 280mm long)

x = 230mm
y = 190mm
z = not more than 190mm

"x" is measured from outside of fascia board on top edge of batten.
"y" and "z" are measured from top edge to top edge. See diagram.

Note 3:
If a mitred hip or mitred valley is required, the battens must be firmly joined in a true mitre along the centre line of the valley or hip rafter, as applicable.


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