HSS Brazilian Green slate is a green coloured roofing slate, produced in Papagaio, Brazil to the strictest extraction and production regulations and is of the highest quality. Produced in two sizes: 600 x 300mm & 500 x 250mm. They are preholed to laps of 100mm. They have a nominal thickness of 5 - 7mm. The slates are split by hand utilising the slate splitters years of experience to produce a product consistent in thickness and texture. The slates are rectangle with chamfered edges and a moderately textured surface. Being a natural product you may get a small variation in the green colour. This adds to the natural appearance of the roof. Slate & a halves are also available. The slate has excellent climatic resistance properties. It is totally unaffected by atmospheric pollution, and is fire resistant. It offers the specifier or builder the ideal roofing product to suit all extremes. Harris Slate & Stone (UK) Limited have the HSS Brazilian slate available at all four of its branches.
Performance Characteristics
HSS Brazilian Slate is regularly tested to BS680 part 2: 1971 requirements for roofing slates. Samples have passed the following parts.
Wetting & drying tests (clause 6.2.2.)
Acid immersion test (clause 6.2.3.)
General Design Considerations.
HSS Brazilian slates when fixed to BS5534 Part1: 1997 Design will have adequate resistance to wind loads, wind uplift and rain penetration under most conditions. The specifier should check the annual driving rain index in BS5534 to decide if the area the slates are being laid is in a moderate or severe exposure area. The site exposure rating and the pitch of roof rafters will determine the size pattern, lap and fixing for the slates.
Sitework
The slates should be stacked on their longer edges with timber bearers, battens or boards between layers. The bottom layer should be on a firm base.
Fixing
The slates should be laid in accordance with the code of practice for slating and tiling BS5534: Part1 1997 and BS8000 Workmanship on building sites Part6: 1990. The slates should be cut on site by hand or machine. When additional holing is required the slates should be drilled from the bed towards the face so that the nail head can sit in the small cavity formed by the area of spalling. Care should be taken to avoid undue spalling. At the time of holing the fixers should be grading the slates into three thicknesses. The thickest to be used at the eaves. Individual slates should be holed so that the thicker end is the tail of slate. Slates should be twice centre nailed as described in the British Standard. Harris Slate & Stone recommend the use of copper nails 40mm in length by 3.35mm diameter to BS1202: Part 2.
Underlay
Protex roofing felt should be used or similar product to BS747: 1994. The underlay should be draped over rafters, or fully supported on boarding. It should allow any moisture to drain and should extend over the tilting piece, fascia board and into the eaves gutter.
Battens
Sizes are recommended in BS5534 for pitched roofs and vertical cladding. Harris recommends the minimum batten size to be 50mm wide x 25mm deep.
Leadwork
Any lead used should be treated with patination oil as it is fixed. If patination oil is not used it could cause unsightly staining to the roof slates.
Ventilation
Adequate ventilation is required for all slate roofs. Ventilation provides the following benefits: Prolonged aesthetic appearance. Avoidance of condensation, resulting in superior insulation performance. Long term protection of roof structure. Harris Slate & Stone have a full range of ventilation products available. See our ventilation data sheet for full details. Accessories A range of GRC ridge tiles are available to suit most roof applications. See separate data sheets for full details.
Accessories
A range of GRC ridge tiles are available to suit most roof applications. See the roofing accessories section for further details.
