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Concrete Slab Costs in NSW

Concrete slab work covers a wide range of project types from a small patio slab in a backyard through to a fully engineered house slab on a reactive clay site, and the pricing range reflects this diversity. NSW pricing in 2026 spans $80 per square metre for a lightly loaded patio or shed slab through to $250 per square metre for an engineered industrial slab carrying heavy loads. House slabs, which are the most common slab type for residential customers, typically fall between $90 per square metre for a waffle pod system on a stable site and $200 per square metre for a conventional raft slab on a moderately reactive Class M site. Sydney's underlying soils mean that most of the metropolitan area requires either a Class M or higher site classification, so reactive site allowances should be assumed in budgeting unless the soils have been confirmed otherwise.

The single most important variable in slab pricing is the site classification under Australian Standard AS 2870 for residential slabs and footings. The standard requires every residential site to be classified based on a soils investigation, with the classification determining the slab depth, the edge beam dimensions, the reinforcement schedule, and whether engineered design is required. A confirmation of site class through a soils report is normally the first step before any meaningful slab quote can be obtained, and reputable concreters and builders will not commit to a slab price without site classification information. The hub page on general concreting services in NSW covers the broader concreting category that surrounds slab work.

What a Concrete Slab Project Includes

A complete residential concrete slab project in NSW takes between four and ten working days on site for a typical house slab depending on slab size, site complexity, and weather. The project sequence covers site cut and fill to bring the building footprint to the design level, excavation of edge beam trenches, installation of plumbing and electrical penetrations through the slab, placement of vapour barrier (typically 200 micron polyethylene under the slab), placement of mesh reinforcement and trench mesh in the edge beams, edge formwork, the pour itself, screed and float finishing, saw cutting of any control joints, application of curing compound or covering with hessian or plastic, and removal of formwork once the slab has set sufficiently.

The materials supplied to site for a typical 200 square metre house slab include around 25 to 35 cubic metres of concrete depending on slab type and edge beam depth, 50 to 60 square metres of mesh in standard sheets, 80 to 120 metres of trench mesh for edge beams, vapour barrier sheeting in 4 metre wide rolls covering the slab footprint plus an overlap, formwork timber and stakes, bar chairs, polystyrene void formers for waffle pod systems, termite protection materials at slab penetrations, and curing compound. The project crew typically includes the lead concreter who manages the pour, two to four labourers for excavation, formwork, and mesh placement, and the concrete truck driver delivering the supply. Larger pours often require a concrete pumper to place concrete from the truck to the slab edge, and our concrete pumping guide covers the boom pump, line pump, and mini pump options used for slab pours.

Beyond the slab itself, a properly scoped quote should include the disposal of excavation spoil, any temporary site works such as silt fencing or sediment control, the saw cutting of expansion joints where required for larger slabs, the formation of any drainage falls, and the tying in of the slab to existing surfaces or footings. Plumbing penetrations and electrical conduits running through the slab should be coordinated with the relevant trades before the pour, with the concreter typically managing the inspection of pre pour positioning. Termite protection at slab penetrations is mandatory under the National Construction Code for residential slabs and should be itemised separately as a builder responsibility rather than left as a slab inclusion. For large slab pours where edge or saw cuts are required after the pour, our concrete cutting guide covers the diamond saw work involved.

Slab Types and Applications

Residential slab work in NSW covers six main slab types, each with different design requirements and price points. The simplest is the patio or shed slab, a 100 millimetre lightly reinforced slab suitable for outdoor entertaining areas, garden sheds, and small workshops with minimal vertical loading. The second is the garage slab, typically 100 to 125 millimetres with edge beams or thickening at the door opening to support the weight of vehicles entering and leaving the garage. The third is the granny flat slab, a residential slab subject to Australian Standard AS 2870 requirements but typically smaller and simpler than a full house slab.

The fourth and fifth types are the two main residential house slab systems used across NSW: the waffle pod slab and the conventional raft slab. Waffle pod systems use polystyrene void formers laid over a flat compacted base, with concrete poured around and over them to produce a slab with integral concrete ribs in a waffle pattern. The system is faster to construct, uses less concrete than equivalent raft slabs, and is well suited to Class A, S, and M sites. The conventional raft slab is built with excavated edge beam trenches, internal beams, and a thinner slab on a compacted fill, producing a heavier and more rigid system suited to Class M, H, and reactive sites where the additional rigidity is needed to bridge soil movement. The choice between waffle and raft is a structural engineering decision based on site classification rather than a matter of homeowner preference.

The sixth type is the industrial or commercial slab, typically 150 to 250 millimetres thick with heavier reinforcement, designed for warehouse loads, forklift traffic, machinery foundations, or commercial floor loads exceeding what a residential slab carries. Industrial slabs are typically engineered specifically for the loads they will carry and are not designed by rule of thumb. For decorative residential slab work where the slab serves both structural and aesthetic purposes, our polished concrete guide and our coloured concrete guide cover the integration of slab construction with finished floor outcomes. For pool surrounds and patios where the slab forms part of an outdoor living area, our concrete patio guide and concrete pool surrounds guide cover the related work.

AS 2870 Site Classification

The Australian Standard AS 2870 classifies residential sites into seven categories based on the reactivity of the underlying soil to changes in moisture content. Class A sites have the most stable soil with little to no movement under typical wetting and drying cycles, found primarily on rocky or coarse sand sites. Class S sites have slight reactivity with minor seasonal movement, common across sandy soils on the Northern Beaches and parts of the Central Coast. Class M sites have moderate reactivity with measurable seasonal movement, which is the dominant classification for most of western Sydney, the Hills District, and the Hawkesbury due to the underlying shale and clay soils. Class H1 and H2 sites have highly reactive soils with significant seasonal movement, found across parts of the Cumberland Plain and around the foothills of the Blue Mountains. Class E sites have extreme reactivity. Class P sites have problem soils requiring specific engineering, including former fill, mine subsidence areas, and soils with abnormal drainage.

The classification has substantial practical implications for slab design and cost. A Class A or S waffle pod slab on a stable site can be built with shallow edge beams, a thin slab section, and standard mesh reinforcement. A Class M raft slab needs deeper edge beams (typically 300 to 500 millimetres), internal beams subdividing the slab into smaller cells, and heavier trench mesh to span between beams. A Class H slab needs even deeper beams (500 to 800 millimetres) and may require piling or screw piers to transfer loads through reactive layers to stable strata below. The cost progression from Class A through Class H is roughly $90 per square metre at the lower end to $220 per square metre at the upper end for the same residential footprint, before considering the engineering and soils investigation costs that the more reactive sites also require.

Determining the site class for a specific property requires a soils investigation, typically involving boreholes drilled to 2 to 4 metres depth at multiple positions across the building footprint, with samples laboratory tested for plasticity index, shrinkage, and other reactivity indicators. The cost of a residential soils report typically ranges from $1,200 to $3,500 depending on the site size and complexity, and the report is a normal precursor to any house slab quote. Skipping the soils investigation to save the cost is unwise because building a slab to a lower classification than the actual site condition is a defect that will manifest as cracking, twisting, and door sticking within the first few years of building life. The NSW Fair Trading guidance on home building defects identifies inadequate slab design for site conditions as a recurring source of major defect claims, with rectification typically costing $30,000 to $80,000 per affected dwelling. For sites where existing slab issues need to be assessed and repaired before new work proceeds, our concrete repair guide covers the rectification options.

Waffle Pod vs Conventional Raft

The choice between a waffle pod slab and a conventional raft slab is one of the most consequential design decisions for any new house slab in NSW. Waffle pod slabs use lightweight polystyrene void formers laid in a grid across a flat base, with concrete poured around and over them to produce a slab with integrated concrete ribs in a waffle pattern. The polystyrene voids reduce the volume of concrete required by 25 to 35 percent compared to a solid slab of equivalent depth, and the construction is faster because no edge beam excavation is required. Waffle pod slabs are well suited to Class A, S, and M sites where the soil reactivity is low to moderate.

Conventional raft slabs are built with excavated edge beam trenches around the perimeter and internal beams subdividing the slab into smaller cells, with a relatively thin slab section poured between and over the beams. The system is heavier, uses more concrete, and takes longer to construct than a waffle pod slab, but provides greater stiffness and load distribution that is essential on reactive sites where soil movement would crack a less rigid slab. Raft slabs are the standard specification for Class M (in some configurations), Class H, and Class E sites. The decision between waffle and raft on a Class M site is often the engineer's call based on specific soils data, with both systems being valid at different ends of the Class M reactivity range.

Cost comparison between the two systems on the same site shows waffle pod slabs typically 20 to 35 percent cheaper than the raft equivalent, due primarily to reduced concrete volume and faster construction. The trade off is that waffle slabs have specific limits on their suitability for reactive sites and cannot be used on Class H or higher sites without specific engineering approval. Recent industry guidance has tightened the conditions for waffle pod use on Class M sites following several high profile defect cases involving waffle pods on sites that were on the boundary between Class M and Class H, and modern engineering practice typically defaults to a raft slab for Class M sites with significant clay content or recent fill. Asking the engineer to specify the slab system rather than the builder is the appropriate sequence on any reactive site, and the engineer's recommendation should be considered binding rather than negotiable. For projects involving slab demolition and replacement on existing sites, our concrete removal guide covers the demolition and disposal logistics.

Reinforcement and Concrete Grade

Steel reinforcement in a residential slab consists of two components: the slab mesh and the trench mesh in the edge and internal beams. Slab mesh is typically SL72 or SL82 sheet mesh in standard 6 by 2.4 metre sheets, manufactured by BlueScope Steel and Liberty OneSteel to Australian Standards specifications, laid on bar chairs to position the mesh at the design height within the slab thickness. Trench mesh is typically L11TM or L12TM (longitudinal trench mesh, 11 or 12 millimetre bars) supplied in 6 metre lengths and lapped at corners and intersections to provide continuous reinforcement around the slab perimeter and through the internal beams.

The reinforcement schedule for a specific slab is determined by the engineer's design, which references the AS 2870 standard slab tables for the relevant site classification. Modifications to the standard tables are common for unusual loadings, large slab spans without internal beams, slabs on steep sites where additional reinforcement is required to handle terrain induced stresses, and slabs with unusual openings or geometry. Substituting cheaper or thinner mesh for the specified reinforcement is a serious defect and is one of the items that an independent slab inspection (where one is engaged) will check before the pour proceeds. Reinforcement specifications should be readable in the slab plans provided by the engineer and should match what is delivered to site.

Concrete grade for residential slabs in NSW is typically 25 MPa for Class A, S, and M sites with standard residential loadings, supplied to Australian Standard AS 1379 by Boral, Holcim, Hymix, Adbri, Hanson, or another major supplier. Higher strengths of 32 MPa are appropriate for Class H sites, slabs in coastal exposure zones within a kilometre of the surf, and slabs subject to heavier loads. Additives including water reducing admixtures, retarders for hot weather pours, and air entrainment for cold weather pours are determined by the supplier based on conditions on the day of the pour. The slab plan typically specifies the minimum concrete grade and any specific admixture requirements; using a lower grade than specified is a defect that should be caught at delivery rather than after the slab is poured. Our concrete grinding guide covers slab flatness rectification work where finished slab levels need correction before subsequent trades can proceed.

Vapour Barriers and Termite Protection

Vapour barriers under a residential slab are mandatory under the National Construction Code Volume Two and serve to prevent moisture migration from the soil through the slab into the building. The standard specification is 200 micron polyethylene sheeting laid across the slab footprint in continuous sheets with overlapped joints sealed with vapour barrier tape, returning up the formwork at slab edges to be folded back over the top of the perimeter beam. Penetrations through the vapour barrier for plumbing, conduit, and other services are sealed individually with proprietary boots or sealant tape to maintain the barrier integrity.

Vapour barrier installation is a quality sensitive task because any breach in the barrier becomes a moisture pathway for the life of the building. Punctures during slab construction (from formwork stakes driven through the barrier, from mesh chairs damaging the membrane, or from foot traffic during the placement of reinforcement) are common defects that compromise the barrier's effectiveness. Reputable concreters protect the vapour barrier during construction and inspect for punctures before the pour proceeds. Independent slab inspection at the pre pour stage typically includes a vapour barrier inspection and is a worthwhile expense for any house slab project, costing $400 to $1,200 for a single inspection.

Termite protection at slab penetrations is required by the NCC for residential buildings in most parts of NSW, with the specific requirements depending on the building's classification under the BCA and the property's location relative to identified termite risk zones. The two main termite protection approaches are physical barriers and chemical treatment systems. Physical barriers including stainless steel mesh and graded stone collars at slab penetrations provide a permanent mechanical barrier against termite ingress and are increasingly preferred over chemical systems for new construction. Chemical termite treatment systems applied to the soil before the slab is poured provide effective protection for 5 to 10 years before requiring reapplication. Both systems should be installed by a licensed pest control operator rather than included in the concreter's general scope. The NSW Fair Trading framework treats termite damage to residential buildings as a serious defect issue and the warranty requirements for termite protection systems should be reviewed carefully before signing the building contract.

Pour Sequencing and Curing

Pour sequencing for a typical residential house slab involves a single continuous pour of the entire slab footprint, completed within a single day to avoid creating cold joints in the slab. A 200 square metre house slab requires 25 to 35 cubic metres of concrete delivered by 4 to 6 truck loads sequenced at 15 to 30 minute intervals to maintain continuous pour without delay. The pour starts at the back of the slab and works towards the access point, with the concrete pump or chute repositioned as the pour progresses. The screed and float work follows immediately behind the pour to finish the slab before the concrete becomes too firm to work. Curing compound or wet hessian is applied immediately after finishing to prevent moisture loss during the critical first 24 hours.

Larger slabs exceeding the volume that can be poured in a single day, or slabs on sites where access constraints limit the number of trucks that can be accommodated within the working day, require staged pours with construction joints between sections. Construction joints are designed and detailed by the engineer to maintain the structural continuity of the slab across the joint, typically using shear keys, dowels, or specific reinforcement laps. Random joints created by running out of concrete or losing a working day to weather are not acceptable construction practice and are typically rectified by additional reinforcement or delayed completion of the pour. Larger commercial and industrial slabs are typically engineered to accommodate construction joints at planned positions, often coinciding with column lines or service penetrations.

Curing protocol during the first 7 days is critical to the slab developing its design strength. The slab must remain damp during this period to allow the cement hydration reactions to proceed fully. Curing compound is the standard approach for residential slabs and forms a film on the surface that retains moisture in the slab. Wet hessian is the traditional alternative and works well but requires daily rewetting. Plastic sheeting can cause condensation marks and is not best practice for slabs that will have visible finishes. Foot traffic should be kept off the slab for 48 hours, light vehicle traffic should be kept off for 7 days, and heavy vehicles including delivery trucks, framing supplies, and brick deliveries should be kept off until day 28 when the slab has reached close to design strength. Premature loading of slabs is a common cause of cracking and surface damage that is entirely preventable. For projects requiring core drilling through completed slabs for plumbing penetrations or service routing, our concrete coring guide covers the diamond core drilling work.

NSW Licensing and Building Code

Concreting work valued above $5,000 in NSW must be performed by a contractor holding a current building licence under the Home Building Act 1989, administered by NSW Fair Trading. The relevant licence categories are structural landscaping or builder. House slabs, garage slabs, and granny flat slabs always exceed this threshold and require licensed work. Builders engaged for the broader house build typically subcontract the slab work to specialist concreting contractors, with the slab forming a defined work package within the broader building contract. Independent slab projects (where a homeowner is engaging the slab work directly without a head contractor) require the slab specialist to hold a builder licence rather than just a concreter or structural landscaping licence.

Residential slabs are subject to the National Construction Code Volume Two for Class 1 dwellings, which incorporates AS 2870 by reference for slab and footing design. Compliance certification for the slab is part of the broader building approval process, with the slab forming one of the inspection stages required by the principal certifying authority. Most metropolitan Sydney councils and certifiers require an inspection at the pre pour stage to confirm reinforcement placement, vapour barrier integrity, and edge beam dimensions, and a further inspection after the pour to confirm the slab has been poured to design specification. Inspection failures at the pre pour stage are common but generally rectifiable; inspection failures after the pour typically require slab replacement. Engaging a competent slab contractor and an independent inspector at the pre pour stage is a more reliable path than rely on the certifier alone.

Most residential slab work for new dwellings requires a development application or complying development certificate under the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008, integrated with the broader dwelling approval. Standalone slab projects for sheds, granny flats, and outbuildings may fall within exempt development for smaller structures, depending on the size and the site classification. The Service NSW portal provides access to council planning information and the relevant Local Environmental Plan for any NSW property. Heritage listed properties and properties within heritage conservation areas have additional approval requirements that can extend the timeline by two to twelve weeks. The Australian Competition and Consumer Commission publishes consumer guidance on residential building contracts that applies to slab work alongside other home building contracts. For sites where excavation safety and subgrade preparation involve specific occupational health and safety considerations, the SafeWork NSW framework applies.

Concrete Slab Costs Across Sydney

Sydney pricing for concrete slab work reflects three main factors: the prevailing site classification across different parts of the city, the density of competing slab specialists in the local area, and the typical complexity of access on residential blocks in different suburbs. Inner Sydney work generally carries premiums for limited access, demolition of existing slabs, and heritage approval overhead. Outer Sydney work is generally cheaper because new build sites are simpler and there is more competition among contractors working within the major release area corridors. The pricing tables below capture typical cost ranges for waffle pod slabs (where applicable to the site class) and for raft slabs as the more conservative option suitable for the dominant Class M sites across most of the metropolitan area.

Inner Sydney pricing for slab work carries premiums driven by access difficulty, the higher proportion of demolition required on infill sites, and the complexity of working within tight urban footprints. Many inner west and eastern suburbs sites require concrete pumping rather than direct truck delivery because of laneway access or building footprint that prevents the truck from reaching the slab edge. Demolition of existing slabs adds a significant line item, with disposal of spoil being a substantial component because of the higher cost of waste handling in inner urban areas. Heritage conservation areas across Paddington, Surry Hills, Newtown, Glebe, and Balmain have additional approval requirements that affect both the timeline and the achievable slab design when existing buildings are being modified or extended.

Western Sydney and the Hills District represent the largest single market for new house slab construction in the state, driven by the major release areas across Marsden Park, Schofields, North Kellyville, Catherine Field, and Oran Park. New build sites in these zones typically have straightforward access for concrete trucks, simple site geometry, established council requirements, and a competitive pool of slab specialists working at scale. Pricing per square metre is consistently 15 to 25 percent below inner Sydney for the same slab specification, and project turnaround from quote acceptance to completed slab can be as short as three to four weeks during normal demand periods. For pathway and patio work that often accompanies new house slab construction, our concrete pathway guide covers the residential pedestrian concreting that complements the main slab work.

Concrete Slab Costs in Regional NSW

Regional NSW pricing for concrete slab work is generally 10 to 20 percent below Sydney pricing for comparable work. Regional sites benefit from simpler access on most rural and regional residential blocks, lower labour rates, and lower compliance overhead in many councils. Concrete supply is sourced from Boral, Holcim, Adbri, and Hanson plants in major regional centres including Newcastle, Wollongong, Dubbo, Tamworth, Wagga Wagga, and Albury. The site classification distribution differs from Sydney with more Class A and S sites in coastal and sandy soil regions, and more Class M to H sites across inland clay country, so the typical slab cost varies by region as much as by labour rate.

Coastal regional NSW pricing across the Mid North Coast and Northern Rivers shows a small premium over inland regional pricing. Coastal sites within a kilometre of the surf require concrete grade upgrades from 25 to 32 MPa to resist chloride attack from airborne salt, adding to the concrete supply cost. The Northern Rivers around Lismore, Ballina, and Byron Bay also has high construction demand combined with limited contractor capacity, keeping pricing elevated relative to comparable inland centres. Sloped sites are more common across the Northern Rivers and the Mid North Coast, requiring stepped slabs or piling that adds to both engineering and construction cost. For sloped site work that combines slab construction with retaining or piled foundations, the structural engineering content is typically substantially higher than for a flat site.

Inland regional NSW including the Central West, the New England, and the Riverina offers the most affordable slab pricing in the state. Local concreters and slab specialists in Dubbo, Tamworth, Wagga Wagga, and Albury can deliver high quality slab work below metropolitan rates because the cost base is lower and most sites are simple to work. The main cost factor for very rural properties is travel time for concrete trucks from the nearest plant, which can add $300 to $1,000 to a pour if the property is more than 45 minutes from the nearest batching plant. Mobile batching is available for very remote sites and typically becomes economic for slab pours above 50 cubic metres. For projects requiring slab resurfacing or structural overlay rather than complete replacement, our concrete resurfacing guide covers the overlay options.

What to Look For in a Concrete Slab Quote

A quality concrete slab quote in NSW is a detailed multi page document that itemises the slab area, the slab type (waffle pod or raft), the slab thickness and edge beam dimensions, the concrete grade, the mesh and trench mesh specifications, the vapour barrier specification, the inclusions and exclusions for excavation, formwork, drainage, plumbing penetrations, termite protection, joint cutting, and disposal. The quote should reference the engineer's slab design by drawing number and date, confirming that the quoted work is to the specification on the latest issued drawings rather than a generic typical detail. A quote without engineering reference is incomplete for any slab subject to AS 2870 design requirements.

Reference checks are critical for slab work because slab defects are expensive to rectify and often invisible until the building is partially built or fully occupied. Ask each prospective slab contractor for the addresses of three to five completed slabs in the past two years that you can drive past, ideally including projects on the same site classification as your project. Check edge beam profile where it is visible above ground, the alignment and squareness of the slab edges, joint cuts and crack control, and any signs of movement around the perimeter that might indicate subgrade issues. Phone references from previous customers are particularly valuable for slab work and should focus on whether the contractor met the schedule, completed the work to design specification, and rectified any defects raised at inspection without dispute. The NSW Fair Trading licence check is a parallel non negotiable step before signing any contract.

Payment terms must comply with the Home Building Act 1989, with a maximum deposit of 10 percent for contracts above $20,000 and 20 percent for contracts below that threshold, and progress payments tied to defined work stages such as excavation complete, formwork and reinforcement complete pre pour, slab poured, and final clean down. Inspection arrangements should be specified in the contract, with at minimum a pre pour inspection by the certifier and an option for an independent slab inspector engaged by the homeowner. The contract should include the engineer's design as a referenced document, the contractor's six year statutory workmanship warranty under the Home Building Act for major defects, and a clear process for raising defects during the warranty period. Where slab cutting or coring work is needed during the slab construction or shortly after, our concrete cutting guide and concrete coring guide cover the specialist saw and core drilling services.

Maintenance and Crack Remediation

Concrete slabs are generally low maintenance once installed correctly, but a few specific maintenance considerations apply. Drainage around the perimeter of the slab should be maintained to prevent water from pooling against the edge beams and migrating into the soil beneath the slab. Reactive site classifications including Class M, H, and E are particularly sensitive to moisture variation, and persistent over wetting (from broken plumbing, blocked agricultural drains, or roof gutter overflow) can cause differential heave that cracks even a properly designed slab. Maintaining stormwater systems, gutters, and subsoil drains around the slab is the most useful long term slab care for reactive sites.

Hairline cracking in a residential slab is normal and is not a defect. All concrete shrinks during the curing process, and the resulting tensile stresses produce minor cracks that are not visible without close inspection. Saw cut control joints are designed to concentrate this cracking along predictable lines where it is invisible in the finished slab. Visible cracks above 1 millimetre wide that develop over time, particularly cracks that progress diagonally across the slab or cracks that show step displacement across the crack line, are potential indicators of structural movement and warrant assessment by a structural engineer. The Home Building Act statutory warranty for major defects covers structural defects in residential slabs for six years from completion, providing recourse where the slab has been built to a lower specification than the site conditions require.

Crack remediation options vary by crack severity. Hairline cracks can be filled with low viscosity epoxy resin injection that bonds the crack and prevents water ingress without affecting structural performance. Wider cracks may require structural injection with high modulus epoxy that restores the slab's load capacity across the crack. Cracks accompanied by step displacement or differential settlement typically require underpinning of the slab edge or affected portions to stabilise the foundation before any cosmetic crack repair will be durable. Slabjacking, a technique where polymer foam is injected beneath the slab to lift settled portions back to level, is appropriate for some settlement cases but is not a substitute for structural rectification where the cause of settlement remains active. Our concrete repair guide covers the full range of structural slab repair options. For slabs that have weathered to a point where the surface finish requires renewal but the structure remains sound, our concrete resurfacing guide covers the overlay options. Post your concrete slab project on The Quote Yard to connect with licensed NSW concreters for house slabs, garage slabs, granny flat slabs, shed slabs, patio slabs, and industrial slabs across Sydney, Newcastle, Wollongong, the Central Coast, the Hunter, and regional New South Wales.