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AS 2050 (roof tile install): pitch, fixing, sarking

AS 2050:2018 is the install standard for concrete, terracotta and slate roof tiles. Minimum pitch by profile, fixing density by wind class, sarking and underlay rules.

By Dan Waring. Last updated 16 May 2026. Verified 16 May 2026.

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In plain English

AS 2050:2018, Installation of roof tiles, is the Australian Standard the tile roofer must demonstrate compliance against on every concrete, terracotta or slate tile roof in Australia. It sets the minimum pitch by tile profile, the fixing density by wind classification, the sarking and underlay requirements, and the flashing and pointing rules. NCC 2022 calls AS 2050 for tile roof installation; non-compliance is a frame inspection fail and an OC blocker (verified 2026-05-16).

The three numbers the builder should hold in their head:

  1. Minimum pitch is profile-dependent. Tiles are rated for a minimum pitch per AS 2050:

    • Standard concrete and terracotta double-Roman tiles: typically 15 degrees minimum.
    • Low-profile (flat) tiles: typically 18 to 20 degrees minimum.
    • Below the minimum, capillary action defeats the lap (see capillary-action-roofing).

  2. Fixing density scales with wind class. Wind classifications under AS 4055:

    • N1, N2 (urban suburbs, sheltered): every 5th tile fixed in body areas, every tile on perimeters.
    • N3, N4 (exposed inland, light cyclonic): every 2nd or every tile in body areas.
    • C1, C2 (cyclonic coastal): every tile fixed, with stronger storm-rated clips.

  3. Sarking is required across most of the country. AS 2050:2018 read with NCC 2022 Part 10.8 (condensation management) requires sarking under tile roofs in climate zones 6, 7 and 8. In warmer zones sarking is recommended, manufacturer-required by all major brands, and effectively standard install practice.

What it requires

For the tile roofer:

  1. Tile selection at or above the minimum pitch for the chosen profile.
  2. Sarking lapped, taped and turned up at the eaves per AS/NZS 4200.2 install rules. Sarking is the secondary water-shedding layer if a tile is lifted or broken.
  3. Battens fixed to the truss layout at the centres required by the tile manufacturer (commonly 320 to 345 mm for concrete tiles, varies with profile).
  4. Tile fixing per the wind classification, using nails, screws, or storm clips. Edge and verge tiles always fixed, regardless of body fixing density.
  5. Ridge cap bedding mortar plus flexible pointing per AS 2050:2018.
  6. Flashings at all junctions (chimney, valley, wall abutment) using metals compatible with the tile and the chimney material.
  7. Valley installation: open metal valley (preferred) with valley boards and a generous tile lap onto the valley sheet.

What it doesn’t cover

  • Sheet metal roofing. Sheet metal sits under AS 1562.1 (Design and installation of sheet roof and wall cladding, Part 1: Metal).
  • Roof structure design. AS 1684 (timber framing) or AS/NZS 4600 (cold-formed steel framing).
  • Truss design and install. AS 1720.5 (design) and AS 4440 (install).
  • Skylight install. Manufacturer’s specification and AS 4285 (rooflights).
  • Solar panel mounting. AS/NZS 5033 (PV array installation) for PV-specific mounting; AS 2050 still applies to the surrounding tile install.

Practical implications

  • Pitch is the most-litigated tile-roof defect. A roof set below minimum pitch leaks at the side laps in driven rain; the leak appears in random ceiling positions and is hard to diagnose. Set the pitch right at the truss design stage; check before the tiler starts.
  • Wind classification before fixing-density commitment. A residential project in coastal NSW with an N3 wind classification needs every-second-tile fixing in body areas at minimum. Builders sometimes assume N1/N2 and fix only every fifth tile; the certifier rejects the install.
  • Pointing is now flexible by default. Cement mortar pointing is the legacy approach; flexible pointing is the modern AS 2050 contemplation and the longer-life option.
  • Cracked tiles found during install must be discarded. A 5% allowance is acceptable for cull, but cracked tiles fitted into the roof telegraph through within 2 years; they’re discoverable on the rust-stained ceiling.
  • Battens must be on every truss, every time. Skipping a batten where the chord positioning doesn’t align is a structural defect; AS 2050 doesn’t permit unsupported tile spans.

References

See also

Last updated: 2026-05-16. Verified: 2026-05-16. Quarterly review for currency.

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