Concrete Slab Cost Sydney 2026: Every Project Type

Concrete slab costs in Sydney (March 2026): house slab $8,000\u201325,000 (80\u2013120m\u00B2), garage floor $4,500\u201312,000 (36\u201360m\u00B2), alfresco/patio $3,000\u20138,000 (25\u201350m\u00B2), path $130\u2013220/lm. Ready-mix concrete (N25) is $210\u2013250/m\u00B3 delivered, but concrete is only 20\u201330% of the total project cost.

MixHub TeamUpdated 22 March 2026

Concrete Slab Costs by Project Type: Sydney 2026

Project typeTypical areaConcrete m³Total installed costCost per m²
House slab (raft)80–150m²12–22m³$10,000–28,000$100–175/m²
Garage floor (single)30–40m²3–4m³$3,200–6,000$90–145/m²
Garage floor (double)50–65m²5–7m³$5,000–10,000$85–135/m²
Alfresco / patio20–50m²2–6m³$2,800–9,000$80–160/m²
Shed floor15–30m²1.5–3.5m³$1,800–4,500$75–120/m²
Concrete path (1m wide)Per metre0.1–0.15m³/lm$130–220/lm$130–220/m²

House Slab Cost Sydney

A house slab (also called a raft slab or slab-on-ground) is the most complex concrete pour a homeowner typically encounters. It requires a structural engineer specification and is closely tied to soil classification (A, S, M, H1, H2, E, P) which dramatically affects the design and cost.

Worked Example: 120m² House Slab, Campbelltown (M-class soil)

ItemCost
Geotech report$800
Structural engineer design$1,200
Formwork and edge boards$2,400
DGB20 base (100mm) + compaction$2,400
DPM (200µm)$600
Reinforcement (N25 steel, M-class)$3,600
Ready-mix concrete (N25, 15m³ + pump)$4,650 + $800 pump
Labour (pour + finish)$3,600
Contractor margin (15%)$2,975
Total (~$190/m²)$23,025

Note: M-class (moderately reactive) soil is common in Campbelltown and western Sydney. H1 or H2 classification can add $3,000–8,000 to the slab cost through additional reo and thicker design.

Garage Floor Slab Cost Sydney

Garage floor slabs are simpler than house slabs: no engineer report required for detached garages on stable ground, no DPM mandatory (though recommended), and typically N25 is sufficient for domestic vehicles.

Garage typeSizeTotal cost (installed)
Single (6m × 6m)36m²$3,500–6,500
Double (6m × 9m)54m²$5,500–10,000

Alfresco / Patio Slab Cost Sydney

An alfresco or patio slab in Sydney costs $3,000–8,000 for a typical 25–50m² area. Exposed aggregate finish adds $1,000–2,000. Prices include N25 concrete, compacted base, reo mesh, and sealant.

For many homeowners, the alfresco slab is the highest-value concrete project because it directly extends your living space. Consider exposed aggregate for a premium finish at a moderate premium ($25–35/m² more than standard broom finish).

What Drives Cost Variation

  • Soil conditions: reactive clay (H1/H2) can add $3,000–8,000+ to a house slab through additional reinforcement and thicker edge beams
  • Reinforcement spec: engineer requirements vary dramatically. Simple SL72 mesh costs $8/m²; complex N-bar cages cost $30–50/m²
  • Site access: tight access requiring a pump adds $600–900 per day. Crane mats for soft ground add $50/day each
  • Finish type: broom finish is cheapest; exposed aggregate adds $25–35/m²; stencilled adds $35–60/m²
  • Concrete grade: N25 is standard; N32 or N40 for reactive soils or heavy loads adds $15–30/m³
  • Contractor competition: get 3+ quotes with identical specs. Labour rates vary 30–50% between contractors

Frequently Asked Questions

How much does a concrete slab cost in Sydney?
Concrete slab costs in Sydney (March 2026): house slab $8,000–25,000 (80–120m²), garage floor $4,500–12,000 (36–60m²), alfresco or patio $3,000–8,000 (25–50m²), path $100–180/m².
How much does a concrete slab cost per m² in Sydney?
A basic concrete slab (N25, 100mm, broom finish) costs $75–130/m² in Sydney. Garage floors with N32 cost $90–150/m². House slabs cost $100–175/m².
What is the cheapest type of concrete slab?
A simple ground-bearing slab on flat, stable ground: N25, 100mm, broom finish on compacted DGB20 base with DPM. Expect $75–100/m² for basic residential applications.
How much concrete do I need for a 10×10m slab?
A 10×10m slab at 100mm thick = 10m³ of concrete. Add 10% waste = 11m³. At $230/m³ (N25, Sydney), that’s $2,530 in concrete alone. Labour and base add $4,000–6,000 more.
What concrete grade for a house slab?
N25 is minimum for residential ground-bearing slabs per AS 3600. Your structural engineer may specify N32 or N40 for reactive soils. Always follow the engineer’s specification.
Does a concrete slab need a structural engineer?
House slabs always need a structural engineer report in NSW. Garage floors, alfresco slabs, and paths on stable ground typically don’t, but check with your council.
How long does a concrete slab take to pour?
An 80–100m² house slab can be poured in one day with a full crew and pump. Smaller garage and alfresco slabs take half a day. The prep work takes 1–3 days before the pour.
How much do concrete footings cost in Sydney?
Strip footings for a house cost $150–300/lm (linear metre) in Sydney. Pad footings for pergolas and decks cost $400–800 each. Costs vary with soil conditions and engineer requirements.
How much is a garage slab in Sydney?
A standard single garage slab (6×6m = 36m²) costs $3,500–6,500 in Sydney. A double garage (6×9m = 54m²) costs $5,500–10,000.
How long does a concrete slab last?
A properly specified and installed concrete slab lasts 50+ years. Driveways and exposed slabs benefit from resealing every 5–7 years. Structural slabs inside buildings can last 100+ years.
What is a waffle pod slab?
A waffle pod slab uses polystyrene pods between the concrete ribs to reduce concrete volume while maintaining structural performance. Common in Sydney suburbs with reactive clay soils. Costs $120–180/m².
What is a raft slab?
A raft slab is a thickened edge slab with internal beams cast monolithically. It’s the standard residential slab type in Sydney. Costs $100–175/m² depending on soil and engineer spec.

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