SPACING BETWEEN THE SLATES
To aid consistent spacing, 6mm spacer tabs are provided on each side of every slate.
The spacers allow for any movement of the roof deck and expansion / contraction of the slate (although thermal expansion is highly unlikely in European climates)
LAYING OUT CUT SLATES
When beginning or finishing with a cut piece of slate, the cut edge should be installed inward. The manufactured edge should be installed to the outside edge of the roof to maintain an acceptable roof appearance along the gable edge of the roof.
The centre mark of the slate can be used as a guide to cut 1 /2 slates. This can also be used as a guide to keep courses straight and to assist in maintaining the 6mm spacing when aligning with intermittent vertical chalk lines.
DO NOT install slates smaller than 76mm
Inspect all areas of the roof surface to be covered.
1. Ensure the surface area is uniformly flat, smooth, sound, clean and free of irregularities.
2. Examine roof sheathing to verify that sheathing joints are supported by framing and blocking and / or metal clips.
3. Verify that substrate is sloped for drainage and completely anchored to sound framing. Any foreign particles shall be cleaned from interlocking areas to ensure proper seating and to prevent moisture intrusion. Proper provisions must be made for flashings and roof penetrations.
4. Metal flashing and other specialty flashings must be in place prior to the roof slate installation. Work by other trades which penetrate the roof plane must also be completed.
5. Product handling and storage on a flat surface is very important. Do not double stack pallets.
1. The starting point may be from the left side, right side or centre of the area to be installed. 6mm spacer tabs are provided on every roof slate.
2. To create an eaves or starter slate, cut a full slate into 3 /4 size.
3. Locate the centre of the roof area to be covered.
From either end, position starter pieces and draw a horizontal line from the top of the starters between these two points. Next draw a vertical perpendicular line. This can be done easily by marking 0.91m along the eave, then where 1.22m and 1.52m intersect will form a perpendicular line. As long as the ratio 3:4:5 stays the same this will hold true, for example, 21:28:35
4. Begin by placing an eaves slate on the right and left side of the vertical line maintaining a 6mm spacing and continue to both ends overhang the eaves by a maximum of 50mm
5. Using a full slate, begin the first course, align centre locator line of the slate directly over the vertical blue chalk line. Adjust the roof slate up or down to align the exposure lines with the top edge of the lower course. Continue to both ends, maintaining the 6mm spacing between slates.
6. Fasten each Guardian Slate with two 30mm x 4mm head stainless steel screws. The fasteners should be placed within the two screw targets on each slate and must penetrate the boarding by at least 12mm.
7. Continue subsequent courses with a full standard slate, the finished edge facing the gable edge.
FELT AND BOARD ROOF
The following instructions are just a guide, and standard roofing procedures should be applied. Apart from the lightness and ease-of-use that Guardian Slate, there is very little difference between it and standard slate roof application. For felt and board roofs, start by fixing timber sheets to the rafters – over vapour permeable underlay. The first course and starter course should oversail the fascia by at least 50mm.
Fix starter course using a 3 /4 cut slate which can be easily cut to size from a full slate using a fine-toothed hand / circular saw or a sharp utility blade. As stated earlier, the first course and eaves (starter) course should oversail the fascia by at least 50mm. This ensures water disperses into the centre of the gutter.
The required gauge and number of courses can then be calculated. The first course should sit on top of an eaves course.
Lay the first course of full slates over the eaves course and fix to the sheet board. Ensure that the first course and eaves course are laid ‘broken bond’ so that the joints do not line up and the weatherproofing integrity is maintained. Lay subsequent courses ‘broken bond’ as illustrated. It will be necessary to cut to start and finish every other course.
RIDGE CAP FINISHING
Guardian ridge caps should be finished by cutting a standard slate at the end of the ridge into a triangle or diamond shape of the right size to cover the end gap. The resulting material should then be screwed in place into the truss. Alternatively, the material can be joined to the ridge cap by using a strong epoxy glue (adhering to the manufacturers instructions). The end piece can be sealed by using a good quality silicon sealant. Screw heads should be disguised with coloured sealant / paint.
HIP AND RIDGE DETAIL
When using pre-formed hip and ridge slates, place screw at fastener guide targets. Fasten hip slates with 2 screws (one on each side). Maintain a 152mm exposure.
Hip and ridge slate installation requires the slate to be screwed in place.
- Draw a straight line in blue chalk by placing one piece of hip at the eave and one near the peak, draw the chalk line at the edge of the slate on the top and bottom pieces. This will help keep the hip straight in the event of a crooked hip.
- If any screw heads are visible, cover with a coloured sealant or paint compatible with the roof slate.
- Preformed ridge slates require 152mm exposure. Use 51mm length fasteners for the slate.
- Fastener deck penetration must be a minimum of 19mm.
- Ridge end closure can be made by cutting a triangular section from a slate and screwing to the timber fillet.
When a ridge tile meets hip tiles, it is necessary to weatherproof this intersection. A lead saddle should be fitted to cover the intersection between the ridge tile and the mitred hip tiles. Guardian slate hip tiles cut easily without splintering or cracking to create a tidy mitred joint.