Roof Cladding

• AS 2049 Roof Tiles
• AS 2050 Installation of roof tiles
• AS/NZS 4597 Installation of roof slates and shingles (non-interlocking type)

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• AS 1562.1 Design and installation of sheet roof and wall cladding – Metal
• AS/NZS 1562.2 Design and installation of sheet roof and wall cladding – Corrugated fibre – reinforced cement
• AS/NZS 1562.3 Design and installation of sheet roof and wall cladding - Plastic

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• AS/NZS 4256.1 Plastic roof and wall cladding materials – General requirements
• AS/NZS 4256.2 Plastic roof and wall cladding materials – Unplasticized polyvinyl chloride (uPVC) building sheets
• AS/NZS 4256.3 Plastic roof and wall cladding materials – Glass fibre reinforced polyester (GRP)
• AS/NZS 4256.5 Plastic roof and wall cladding materials – Polycarbonate

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• AS 1684 Residential Timber Framed Construction

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• AS 4200.1 Pliable building membranes and underlays - Materials
• AS 4200.2 Pliable building membranes and underlays - Installation requirements
• AS 1530 Methods for fire tests on building materials, components and structures
• AS 1397 Steel sheet and strip
• AS 4859.1 Materials for the thermal insulation of Buildings
• AS 3959 Construction of buildings in bushfire prone areas
• AS/NZS 4994.2 Temporary roof edge protection for housing and residential buildings – installation and dismantling.
• AS 4046.8 Adhesive mechanical fasteners – Flexible pointing

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Roof cladding installation shall comply with the Drawings, Building Regulations and relevant Standard (AS 2050 tiles, AS/NZS 4597 slates, AS/NZS 1562.1 metal, AS/NZS 1562.2 fibre-reinforced cement , AS/NZS 1562.3 plastic). Refer also to the specification on Roof Plumbing. For construction in areas that are prone to bushfire, all materials and construction shall comply with the Building Regulations and relevant Standard (AS 3959, ..BCA Vol 2 Part 3.7.4.) Unless stated otherwise, the following shall apply.

Commencement

Work shall commence as soon as practical after, but not before,
(a) the Builder has issued:

• a written order
• the relevant contract drawings, specifications and schedule of work
• written approval of any details provided by the Contractor

(b) the roof framing is constructed and approved.

Installation of Tiled Roofs

For tiled roofs, the following shall apply:

• Timber battens or galvanized steel battens shall be installed, with strength and stiffness to resist wind uplift and gravity loads (in-service and during construction), in accordance with the Building Regulations and the relevant Standards (AS 1684, BCA Vol 2 Part 3.4.3, BCA Vol 2 P2.1 & P2.2). Battens shall be suitable fixed to trusses or rafters, such as to resist net wind pressure.
• Sarking shall be installed under roof battens in accordance with AS 4200.2. Bulk insulation may also be required. Refer to specification on Insulation.
• Roof tiles shall be fixed in accordance with the Building Regulations and the relevant Standards. (AS 2050, ..BCA Vol 2 Figures 3.5.1.1 and 3.5.1.2 and Wind Category) and not less than the following:

For Wind Category less than W33: Mechanically fix each full tile in second course adjacent to the edge of the roof Mechanically fix the end four ridge tiles Mortar fix the hip ridge tiles Mechanically fix each barge tile

For Wind Category W33-W41: Mehanically fix each full tile in second course adjacent to the edge of the roof Mechanically fix each second full tile in the field of the roof Mechanically fix every ridge tile Mechanically fix the end four hip ridge tiles Mechanically fix each barge tile At any firewall, mineral wool shall be supplied and packed between the sarking and the top of the wall.

Sheet Metal Roofs

For sheet metal roofs, the following shall apply:

• Timber battens or galvanized steel battens (or purlins and girts) shall be installed, with strength and stiffness to resist wind uplift and gravity loads (in-service and during construction), in accordance with the Building Regulations and the relevant Standards (AS 1684, BCA Vol 2 Part 3.4.3, BCA Vol 2 P2.1 & P2.2). Battens, purlins and girts shall be suitable fixed to trusses, rafters, beams, columns or frames, such as to resist net wind pressure.
• Blanket insulation shall be fixed between the metal roof sheeting and the battens. Alternatively, bulk insulation may also be required. Refer to specification on Insulation.
• Roof sheeting shall be fixed in accordance the manufacturer’s recommendations for the particular wind category and the Building Regulations (BCA Vol 2 Figures 3.5.1.5 for Wind Category W33 or W41).

For Wind Category W33 or W41, fixings shall not be less than as set out below. Profile Base metal thickness (mm) End span (mm) Internal span (mm) Fixing End Span Internal Span Corrugated 0.42 950 1200 Every second rib Every third rib Close pitched trapezoidal 0.42 1900 2400 Every rib Every second rib Trapezoidal 0.42 1350 1700 Every rib Concealed fasteners 0.48 1800 2100 Every rib

• Roof sheets shall be laid in continuous lengths where practical. If this is not practical, the correct laps and fixings specified by the manufacturer shall be used.
• The upper end of the roof sheets shall be turned up, using the correct tool. In high wind areas, turn the sheets down into the eaves gutter at the lower end.
• Sheets shall be fixed through the high point of the ribs using long screws, not valley fixed.
• At any firewall, mineral wool shall be supplied and packed between the sarking and the top of the wall.

The following inspections shall be performed.

Tiled Roofs

Item or Product Inspection Required Accept Criteria Hold / Witness Drawings & Specifications Inspect controlled documents Controlled copy of latest issue on site Hold Sarking Type Fixing   Visual Visual   As specified As specified   Hold Witness Battens Dimensions Fixing   Spot check Visual   As specified As specified   Hold Witness Tiles Colour, style Fixing Grouting Waterproof   Visual Visual Visual Hose roof   As per sample As specified As specified No leaks   Hold Witness Witness Witness Insulation at fire wall Visual In position Witness

Sheet Metal Roofs

Item or Product Inspection Required Accept Criteria Hold / Witness Drawings & Specifications Inspect controlled documents Controlled copy of latest issue on site Hold Sarking Type Fixing   Visual Visual   As specified As specified   Hold Witness Battens Dimensions Fixing   Spot check Visual   As specified As specified   Hold Witness Roofing Colour, style Fixing Turn up / down at the ends Sealing Waterproof   Visual Visual Visual Visual Hose roof   As per sample As specified As specified As specified No leaks   Hold Witness Witness Witness Witness Insulation at fire wall Visual In position Witness

Safety on Roofs

The roofing contractor should provide safety rails where required by the workplace health and safety authority.

Tile Roof Fixing

Ensure that tiles are fixed down to the battens in accordance with BCA and Australian Standard requirements by spot-checking particular areas (eg adjacent to ridges).

Sheet Roof High Wind Fixings

Special care is required to ensure that sheet roof are correctly tied down in high wind areas using the correct fixings specified by the manufacturer and as specified in AS 1170.2 and AS 4055. The tie-down requirements should be determined for the appropriate Region, Terrain Category, Topography and Shielding and recorded on the drawings by the design engineer. Although this should be specified on the drawings, it may be necessary to check the requirements with the manufacturer.

Weatherproofing

Sheet metal roofs are often constructed at low pitches or in high wing areas. These two factors combine to make sheet metal roofs more prone to the ingress of wind-blown water. To minimise this problem, lay the sheets in continuous lengths where practical. If this is not practical, use the correct laps and fixings specified in the BCA and by the manufacturer. Ensure that the upper ends of the sheets are turned up, using the correct tool. In high wind areas, it may also be advisable to turn the sheets down into the eaves gutter at the lower end. Sheets should be fixed through the high point of the ribs using long screws, not valley fixed.

Corrosion of Sheet Roofs

All flashings must be of a type compatible with the flashings, gutters or other metal items. Particular requirements apply for severe conditions, such as close to the sea with frequent on-shore winds and in local areas with heavy industrial pollution. Fixings for sheet roofs should be supplied with rubber washers to isolate the fixing from the sheet, to avoid galvanic corrosion.

Flashings

Roofs shall be appropriately flashed using soft material that can be easily bent to shape, such as zinc sheeting or pre-painted sheet metal. All flashings must be of a type compatible with the roof sheeting, gutters or other metal items, to avoid corrosion. Lead flashings shall not be used in conjunction with or upstream of zinc-aluminium coated materials or to channel potable water. Copper materials shall not b e used in conjunction with or upstream of galvanized materials.

Checking Roof Leakage

Roof leakage may be difficult to detect after the fixing of the ceiling. Therefore, test the roof by vigorous hosing before proceeding to sheet the ceiling.

Sheet Roof Colours

Some of the “standard” colours supplied by roof sheeting manufacturers are less common than others, and their availability may be limited, thus causing potential delays in the job. Always check availability before committing to the proposed colour scheme.

Roof Touch-up Sheet

The paint system used for colouring steel roof sheeting is a sophisticated system employing heat curing. If roof sheeting should be scratched, it is usually best to leave it as is, rather than attempt a “touch up” repair. Although you may be successful in matching the colour, the original paint and the repair could weather differently, exacerbating a problem that may otherwise have gone unnoticed.