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Roof tiles installation: concrete and terracotta, AS 2050

Roof tiles installation guide for Australian builders: AS 2050:2018, concrete vs terracotta, sarking, batten spacing, wind class fixing, ridge bedding vs dry-fix.

By Dan Waring. Last updated 8 May 2026. Verified 8 May 2026.

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TL;DR

Roof tile installation in Australia is governed by AS 2050:2018 and NCC 2022 Housing Provisions Part 7.3. The standard covers both concrete and terracotta tiles for pitches of 15 degrees or more on wind classes N1 to N6 and C1 to C4. Sarking is mandatory on any tiled roof under 18 degrees pitch, and on longer rafters at pitches between 18 and 22 degrees. Fixing pattern escalates with wind class: at N3, every second full tile in every course must be mechanically fixed. Ridge and hip tiles must be individually fixed at N1 and above. Traditional cement bedding and pointing is still permitted, but flexible pointing compounds and mechanical dry-fix systems have become the default on new work. The single biggest defect trigger at PCI is pointing failure or cracked bedding on ridges and hips; the second is gutter overhang outside the 35 to 65 mm range.

When you do this

Roof tile installation follows:

  • Roof frame completion and any required engineer sign-off on the frame
  • Installation of fascia and barge boards
  • Plumber’s installation of penetration flashing sleeves (before tiling)
  • Any required bushfire (BAL) roofing underlays if applicable

Tiling is typically a hold point: the certifier or building inspector usually checks the roof frame, sarking, and flashings before tiling over them.

Who’s involved

RoleResponsibility
Roofer (roof tiler)Sarking, batten layout, tile installation, ridge/hip bedding or dry-fix, flashings
BuilderCoordinate access, confirm wind class on engineering drawings, pre-tile inspection sequencing
Certifier / building inspectorInspection of sarking and battens before tiling proceeds (in most jurisdictions)
PlumberPipe penetration flashings, which must be installed before the roofer laps tiles over
EngineerConfirms wind class; specifies any tie-down or bracing requirements for the roof frame
Pest managerSarking must integrate correctly with termite management if eave or tile design intersects the 75 mm termite inspection zone

Steps

1. Confirm wind class and tile specification

Before ordering tiles or booking the roofer, confirm the site wind class from the engineer’s structural details. The wind class (N1 to N6, or C1 to C4 in cyclonic zones) determines the required tile fixing pattern under NCC 2022 Housing Provisions Table 7.3.2. It also limits what products are NCC-compliant: the Housing Provisions DTS provisions for roof tiles apply only to wind classes N3 and lower; N4 and above require specific engineering design for the tiling system (verified 2026-05-08: NCC 2022 ABCB Housing Provisions Part 7.3).

Concrete vs terracotta: both tile types are covered by AS 2050:2018 and AS 2049:2014 (the tiles standard). The practical differences for installation:

PropertyConcrete tilesTerracotta tiles
WeightHeavier (typically 40 to 50 kg/m2)Lighter (typically 30 to 40 kg/m2)
Minimum pitch15 degrees (standard profiles)15 degrees; low-profile terracotta can vary
Structural impactHeavier; confirm trusses/rafters sized for loadLighter load; confirm with engineer if switching types
Water absorptionAround 13%; surface coating needed long-termAround 6%; glazed surface is inherently sealed
Lifespan50 years typical100 years+ with correct installation
Colour stabilityCoating fades over time; rebedding cycle typically 15 to 25 yearsKiln-fired colour is permanent
Source[Monier, Bristile, Boral][Terracotta Italia, Boral]

Structural note: the engineer designs trusses or rafters to the specified tile load. If the tile type changes after the frame is designed, notify the engineer before proceeding.

Source: AS 2050:2018 Installation of roof tiles (verified 2026-05-08); AS 4055:2021 (verified 2026-05-08).

2. Set out battens

Battens are sized per AS 1684 (timber) or the manufacturer’s specification. Batten spacing is determined by the tile manufacturer’s technical specification for the specific tile profile: the spacing controls the tile head lap (the overlap between tile rows), which is pitch-dependent.

Key requirements per NCC 2022 Housing Provisions and AS 2050:2018:

  • Battens must be fixed securely to rafters or truss top chords per AS 1684
  • The batten layout determines the gauge (spacing between centres), which is specific to each tile product and roof pitch
  • At roof edges (barge and eave), first and last batten positions are set to achieve the required overhang (see water discharge below)
  • Batten splice joints must occur over a rafter, not in a free span

Typical residential batten sizes under AS 1684 for tiled roofs: 38 x 50 mm or 38 x 75 mm F7 or F8 stress-graded timber at standard rafter spacings. Confirm the specific size from the AS 1684 span tables using the wind class, batten span (rafter centres), and tile weight.

Source: NCC 2022 ABCB Housing Provisions Part 7.3 (verified 2026-05-08).

3. Install sarking

Sarking must be installed per NCC 2022 Housing Provisions clause 7.3.4. The requirement depends on roof pitch and rafter length:

Roof pitchMaximum rafter/truss chord length without sarking
Less than 18 degreesSarking mandatory regardless of rafter length
18 degrees to less than 20 degrees4,500 mm maximum
20 degrees to less than 22 degrees5,500 mm maximum
22 degrees or more6,000 mm maximum

Where rafter length exceeds the threshold, sarking is required over the length exceeding the threshold (towards the eave end). In practice, most builders install full-roof sarking on all tiled roofs: the cost is low and the risk management benefit (secondary waterproofing layer, condensation management, dust and wind-driven rain exclusion) is high.

Installation specification (clause 7.3.4):

  • Sheets lapped minimum 150 mm at joints, or sheets taped at all joints
  • Secured at maximum 300 mm centres
  • Maximum 40 mm sag between fixings (prevents water ponding on the sarking)
  • Sarking must be lapped correctly: lower sheets over higher sheets (shingle principle)

Climate zones 6, 7, and 8 (NCC 2022 Part 10.8 condensation management): in these cooler zones, the sarking specification affects condensation compliance. Where sarking is installed, it must have a vapour permeance of not less than 1.14 μg/N.s, and a minimum 20 mm ventilated air gap must be maintained between the sarking and the underside of the insulation layer. Reflective foil sarking (low vapour permeance) in these zones can trap moisture and create a condensation defect. Confirm sarking product suitability against the climate zone for any project in ACT, alpine VIC, Tasmania, or southern VIC (verified 2026-05-08: NCC 2022 Part 10.8 Condensation management).

Source: NCC 2022 ABCB Housing Provisions clause 7.3.4 (verified 2026-05-08).

4. Install anti-ponding board (where required)

An anti-ponding device is required by NCC 2022 Housing Provisions clause 7.3.5 in two situations:

  • The roof pitch is below 20 degrees and sarking has been installed
  • The roof has no eaves overhang (zero-eave or parapet design)

The device must be:

  • Water-resistant material
  • Fixed along the eaves line, running from the top of the fascia back up the rafter
  • Positioned with approximately 50 mm clearance below the first batten

The function is to direct any water that runs down the sarking outward over the gutter rather than pooling behind the fascia.

Source: NCC 2022 ABCB Housing Provisions clause 7.3.5 (verified 2026-05-08).

5. Install penetration and wall flashings

All flashings must be installed before tiling. Flashing requirements per NCC 2022 Housing Provisions clause 7.3.3:

Wall and step flashings:

  • Minimum 75 mm upturn behind cladding or into mortar joint
  • Minimum 150 mm total flashing width (measured across the slope)
  • Joints lapped minimum 75 mm, lapped downslope (upper over lower)

Penetration flashings (pipes, vents, skylights):

  • Minimum 75 mm upturn around all sides
  • Minimum 150 mm width surrounding the penetration
  • Lead flashing is prohibited in drinking water catchment areas (use non-ferrous alternatives: aluminium, zinc, copper, or EPDM proprietary systems)

Integration with sarking: flashings must be lapped under the sarking above and over the sarking below. A flashing installed over sarking that is below it is a defect: water will wick behind the flashing along the sarking face.

The roofer installs flashings; the plumber installs the pipe sleeves first, and the roofer laps tiles and flashing over the sleeve. Coordinate sequencing before mobilising.

Source: NCC 2022 ABCB Housing Provisions clause 7.3.3 (verified 2026-05-08).

6. Lay field tiles: fixing pattern by wind class

Tile fixing is the single most wind-class-sensitive step. NCC 2022 Housing Provisions Table 7.3.2 sets out the minimum fixing pattern:

Wind classRoof edge tilesField of roof tilesRidge, hip, barge, and capping tiles
N1, N2Fix every full tile in the second course in from the edgeFix every second tile in a course, OR every tile in alternate coursesFix each tile individually
N3Fix each full tile in every second course starting from second courseFix every second full tile in every courseFix each tile individually
N4 and aboveEngineering design required; DTS provision does not apply

“Fix” means one of the following acceptable methods (clause 7.3.2(2)):

  • Galvanised clout nail: minimum 2.8 mm diameter, penetrating at least 15 mm into the batten
  • Self-embedding head screw: 8 to 18 gauge, minimum 15 mm batten penetration
  • Non-ferrous or stainless steel clip (corrosion protected, compliant with AS 2050)
  • Flexible pointing per AS 2050 (only for field tiles; not acceptable as the sole fixing for ridge/hip)

On cyclonic-class sites (C1 to C4), the DTS Housing Provisions do not apply, and engineering specification is required for the tiling system.

Source: NCC 2022 ABCB Housing Provisions Table 7.3.2 and clause 7.3.2 (verified 2026-05-08).

7. Water discharge: gutter overhang

Tile overhang into the gutter is set by NCC 2022 Housing Provisions clause 7.3.6. The eave course of tiles must overhang the fascia or eave batten by a minimum of 35 mm (inner face of the gutter). Standard practice is 50 mm overhang, measured to the inside face of the fascia or gutter.

This is a common defect at PCI: eave tiles sitting too far back (less than 35 mm) will let water run between the gutter and the fascia; tiles projecting too far (more than 65 mm) overhang the gutter to the outside face and miss the gutter entirely.

Source: NCC 2022 ABCB Housing Provisions clause 7.3.6 (verified 2026-05-08).

8. Ridge and hip tiles: bedding, pointing, or dry-fix

Ridge and hip tiles are the highest-failure-rate element on a tiled roof. Every ridge and hip tile must be individually fixed at wind class N1 and above (Table 7.3.2).

Method 1: Cement bedding and pointing (traditional)

  • Bedding mortar: typically 3 to 4 parts sand (bricklayer’s sand) to 1 part Portland cement, mixed to a stiff but workable consistency
  • Ridge tile set into bedding mortar, positioned, and tapped to alignment
  • Pointing applied over the bedding: traditionally a flush or slightly tooled cement finish, now commonly an acrylic or flexible polymer compound
  • Flexible pointing compounds are strongly preferred on new work: they accommodate thermal movement of the roof without cracking, and do not degrade like cement-only pointing

Pointing is defective if it becomes dislodged, is washed out, is not uniform in colour and texture, or does not present a neat trowelled appearance. Minor hairline cracking in cement pointing is not defective per the state Guides to Standards and Tolerances; cracking that leads to water ingress or dislodgement is defective.

Method 2: Dry-fix mechanical ridge system Dry-fix systems use a weather-resistant fleece strip and mechanical fixings to secure ridge caps without mortar. A butyl-strip seal between the tile and ridge cap provides weather tightness. No bedding or pointing is required.

Dry-fix systems do not degrade over time in the way that cement bedding does, eliminate cracking and repointing maintenance, and are increasingly specified on new builds. They comply with AS 2050:2018. Confirm the specific product is compatible with the tile profile and rated to the site wind class.

HIA Guide tolerances for ridge tile alignment: the HIA Guide to Materials and Workmanship contains the numerical tolerance for ridge tile line and level. This value requires HIA member access. [HIA-050]

Source: NCC 2022 ABCB Housing Provisions clause 7.3.2 and Table 7.3.2 (verified 2026-05-08); AS 2050:2018 Standards Australia (verified 2026-05-08).

Tolerances and acceptance

Roof tile workmanship tolerances are set primarily by the state Guides to Standards and Tolerances and the HIA Guide to Materials and Workmanship. The following are drawn from the Victorian VBA Guide to Standards and Tolerances 2015 and are broadly consistent with the NSW and QLD equivalents; always confirm against your state’s current guide.

ElementStandardRequirement
Cracked or broken tilesState Guides to Standards and TolerancesDefective if caused by the builder’s workmanship
Tiles not conforming to manufacturer sampleState GuidesDefective
Tile alignment (ridges, hips, verges, valleys)State GuidesDefective if not cut neatly to present a straight line
Gutter course of tilesState GuidesDefective if not on the same plane as the rest of the roof
Gutter overhangNCC 2022 HP clause 7.3.6Minimum 35 mm, maximum 65 mm overhang of inside face of gutter
Pointing: uniformityState GuidesDefective if not uniform in colour, texture, and trowelled neatly
Pointing: dislodgementState GuidesDefective if dislodged or washed out
Pointing: minor crackingState GuidesMinor hairline cracking is not defective
Ridge tile line and levelHIA Guide to Materials and WorkmanshipNumerical tolerance pending HIA member access. [HIA-051]
Sarking installationNCC 2022 HP clause 7.3.4Maximum 40 mm sag; minimum 150 mm lap; fixed at maximum 300 mm centres

Source: VBA Guide to Standards and Tolerances 2015 (verified 2026-05-08); NCC 2022 ABCB Housing Provisions Part 7.3 (verified 2026-05-08).

Documents needed

  • Engineering structural details (confirms wind class, truss/rafter design loads for specified tile weight)
  • Tile manufacturer’s technical data sheet (batten gauge per pitch, weight per m2, minimum pitch)
  • Construction Certificate or building permit with inspection schedule
  • Sarking manufacturer’s product data (vapour permeance for climate zone compliance)
  • Certifier’s or inspector’s approval for pre-tile inspection before tiling proceeds
  • SWMS (Safe Work Method Statement) for working at heights on a pitched roof

Common holds

  • Wind class not confirmed before ordering tiles. The tile fixing pattern, and whether the DTS NCC provisions even apply, depends on the wind class. A roofer quoting without a confirmed wind class is quoting into an unknown. Get the wind class from the structural drawings first.

  • Sarking lapped the wrong way. Sarking must be lapped upper-over-lower (shingle principle). Sarking lapped lower-over-upper channels water into the lap and behind the sarking. It’s invisible once tiled; it shows up as water ingress at the eave in the first heavy rain.

  • Anti-ponding board omitted on a low-pitch roof. On any pitch below 20 degrees with sarking, the anti-ponding board at the eave is mandatory. Without it, water tracks back along the sarking and behind the fascia. Certifiers check this.

  • Flashings installed after tiling. Penetration flashings and wall flashings must go in before tiling. A flashing retrofit through a laid tile roof involves breaking tiles or relying on surface-applied sealants, neither of which is a compliant solution.

  • Pointing applied too wet or too thin. Wet-applied mortar pointing shrinks and cracks on drying if applied too wet. Pointing applied too thin over the bedding has poor adhesion. Standard failure mode: pointing gone within 10 to 15 years on a 30-year-old roof. Flexible acrylic compounds eliminate this.

  • Ridge tiles not individually fixed at N1 and above. Table 7.3.2 requires every ridge, hip, barge, and capping tile to be individually mechanically fixed at any wind class. Bedding alone (without a mechanical fixing) is non-compliant.

  • Sarking vapour permeance wrong for the climate zone. In climate zones 6, 7, and 8, reflective foil sarking (low vapour permeance) can trap moisture. Using the wrong sarking product in these zones creates a condensation defect that is invisible until mould or rot appears in the roof frame.

References

See also

Last updated: 2026-05-08. Verified: 2026-05-08. Quarterly review for currency.

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