NCC 2019 Volume Two Amendment 1
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Appropriate Performance Requirements
Where an alternative roof cladding is proposed as a Performance Solution to that described in Part 3.5.1, that proposal must comply with—
Performance RequirementsP2.1.1 and P2.2.2 are satisfied for roof cladding if it complies with one or a combination of the following:
Roof tiling: AS 2050.
Terracotta, fibre-cement and timber slates and shingles: AS 4597.
Compliance with this acceptable construction practice satisfies Performance Requirements P2.1.1 and P2.2.2 for roof tiles, provided—
the building is located in an area with a design wind speed of not more than N3; and
the roof tiles comply with AS 2049; and
the roof has a pitch of not less than 15 degrees and not more than 35 degrees, and
the roof tiles are installed in accordance with the provisions of this Part.
Information on design wind speed for particular areas may be available from the appropriate authority. Also see Table 3 for wind classes. A map indicating wind regions of Australia is contained in Part 3.0.
A number of other Parts of Volume Two contain specific requirements relevant to roof tiles, in addition to the provisions of this Part. They include—
Roof tiles and hip, ridge, barge and capping tiles must be fixed in accordance with Table 3.5.2.1 and Figures 3.5.2.1 and 3.5.2.2.
Fixing required by Table 3.5.2.1 must consist of one or a combination of the following:
Galvanized clout nails with a minimum diameter of 2.8 mm and of a length so that the nail will penetrate not less than 15 mm into the batten.
Self embedding head screws of 8-18 gauge and of a length so that the screw will penetrate not less than 15 mm into the batten.
Purpose made clips of non-ferrous metal, stainless steel or steel protected from corrosion in accordance with Tables 3.5.1.2a and 3.5.1.2b.
Flexible pointing material complying with AS 2050.
Tile fixing - edge of roof |
Tile fixing - field of roof |
Ridge, hip, barge and valley tiles including capping (see Figure 3.5.2.2 ) |
|
N1 and N2 |
Fix every full tile in second course in from the edge of roof |
In field of roof fix—
|
Fix each tile |
N3 |
Fix each full tile in every second course starting from the second course in (see Figure 3.5.2.1c) |
Fix every second full tile in every course (see Figure 3.5.2.1c) |
Fix each tile |
Note to Table 3.5.2.1: Refer to Figure 3.5.2.1 for determination of "edge of roof" and "field of roof".
For the purpose of this Figure, "edge of roof" is a 1.2 m wide band bounded by the eaves, hips and barge measured towards the "ridge of roof".
Flashing for roof tiles must comply with the following:
Wall and step flashings:
For masonry or similar walls, flashing must—
follow the roof line, allowing not less than 75 mm upturn to the wall and a minimum of 150 mm in width and moulded into the tiles; and
have joints overlap the one below by not less than 75 mm in the direction of flow.
For flashing where the upturn can be fixed to or behind the supporting frame or cladding, it must—
follow the roof line, allowing not less than 75 mm upturn to the wall and a minimum of 150 mm in width and moulded into the tiles; and
be fastened into or behind the wall cladding at each end and at a maximum of 600 mm centres; and
have joints overlap the one below by not less than 75 mm in the direction of flow.
Flashing of penetrations must—
be either collar, apron or other purpose made flashings; and
have a minimum upturn on the penetration of not less than 75 mm and a minimum of 150 mm in width surrounding the penetration and be moulded into the tiles; and
permit the total drainage of the area above the penetration.
Joints in flashing must be not less than 75 mm and lapped in the direction of fall of the roof.
Lead flashings must not be used on any roof that is part of a potable drinking water catchment area.
Acceptable flashing configurations, including typical details for standard, and bedded and pointed valleys, are shown in Figure 3.5.2.3.
Sarking must—
be provided in accordance with Table 3.5.2.2; and
comply with AS/NZS 4200.1 and be installed with—
each adjoining sheet or roll being—
overlapped not less than 150 mm; or
taped together; and
sarking fixed to supporting members at not more than 300 mm centres; and
no sags greater than 40 mm in the sarking.
Roof pitch |
Maximum rafter/truss top chord length without sarking (mm) Note 1 |
---|---|
<18° |
N/A Note 2 |
>18° <20° |
4 500 |
>20° <22° |
5 500 |
>22° |
6 000 |
Notes to Table 3.5.2.2 :
Where sarking is also provided as reflective insulation for the purpose of energy efficiency, Part 3.12 contains required R-values and the necessary airspaces adjoining the reflective insulation.
An anti-ponding device/board must be provided where sarking is installed on—
roofs with a pitch less than 20o; and
roofs with no eaves overhang, regardless of the roof pitch.
An anti-ponding device required by (a) must be water resistant and fixed along the eaves line from the top of the fascia back up the rafter with a clearance of approximately 50 mm below the first batten (See Figure 3.5.2.4).
Where an eaves gutter is provided in accordance with Part 3.5.3, tiles must overhang the fascia or tiling batten by not less than 35 mm (See Figure 3.5.2.4).