Concrete slabs and shed bases in the Sutherland Shire
Updated October 2026
Whether you need a shed base in Engadine, a garage slab in Kirrawee or a granny flat slab behind a Miranda duplex, the slab is the part of the job you never want done badly. We connect you with experienced, insured local concreters who pour slabs across the Sutherland Shire. We are a referral service, not a concreting business, so your job goes to a contractor suited to its size and complexity.
Common slab jobs in the Shire
- Shed and workshop bases
- Garage and carport slabs
- Granny flat and studio slabs
- House slab extensions
- Pool surrounds and equipment pads
- Hot water, tank and air conditioner pads
Knockdown-rebuild and duplex activity around Caringbah and Miranda also drives steady demand for new garage slabs and driveways.
What a concrete slab costs
Guide pricing only. Published 2026 Australian figures put a plain concrete slab at roughly $75 to $150 per square metre supplied and laid, with around $110 typical, and Sydney tends toward the upper end. Small pads often cost more per square metre than that range suggests because the fixed costs of the truck, crew and setup are spread over fewer metres. Site conditions move the price more than the finish does. Get a fast quote for a real number on your block.
How a slab is built
A good slab is mostly about what happens before the truck arrives.
1. Excavation to a level base and removal of topsoil
2. Compacted road base or crushed rock
3. Formwork set to height with correct falls for drainage
4. A plastic vapour barrier where required
5. Steel mesh reinforcement on bar chairs, not lying on the ground
6. The pour, screed and finish
7. Curing, then control joints cut or tooled to manage shrinkage cracking
Shed slabs are commonly 100mm thick with SL72 mesh. Slabs carrying vehicles or machinery are often 125mm or more with heavier mesh. Thickened edge beams suit sheds that bolt down to the perimeter.
Soil matters, especially around Menai
Reactive clay soils around Menai, Bangor and Barden Ridge swell when wet and shrink when dry, which can crack a slab that was not designed for the site. Contractors working in these suburbs allow for it with deeper edge beams, extra reinforcement or piering where needed. Sandier soils closer to Cronulla and Kurnell behave differently again, and coastal salt air is a reason to insist on proper concrete cover over the steel.
Council approval
Many small sheds and slabs fall under exempt development rules in NSW, but size, height and boundary setbacks all have limits. Larger sheds, granny flats and habitable structures need approval through council or a private certifier. Check with Sutherland Shire Council before you pour, and note that for driveways crossing the footpath a crossover permit is usually needed. A slab poured without required approval can be expensive to unwind.
Licensing
In NSW, residential building work worth more than $5,000 (labour and materials, including GST) must be done by a licensed contractor. Plenty of slab jobs cross that line once excavation, steel and concrete are added up. Our referral service connects you with appropriately qualified, insured contractors.
Site factors that move the price
- Access. If the truck cannot get close, a concrete pump or barrows add cost. Steep blocks in Jannali, Woronora and Illawong often need a pump.
- Cut and fill. Sloping sites need more excavation and sometimes retaining.
- Old concrete. Breaking out an existing slab adds demolition and tip fees.
- Engineering. Reactive soil or a heavy structure can require an engineered design.
- Weather. Rain delays pours, and summer heat means early starts. A slab poured in the wrong conditions is a slab you pay for twice.
How long a slab lasts
A well built slab on a properly prepared base should last 40 years or more with no drama. Hairline shrinkage cracks are normal. Wide, stepped or sunken cracking is not, and our concrete repairs page covers the options if you have an older slab moving.
Ready to price your shed base or slab? Get a fast quote and compare local contractors.
Frequently asked questions
How thick should a shed slab be?
100mm with SL72 mesh suits most garden sheds and workshops. Go to 125mm or more if the shed will house a vehicle, hoist or heavy machinery. Your contractor will confirm once they see the soil and the shed specs.
Do I need council approval for a shed slab?
Small sheds often qualify as exempt development, but limits apply to size, height and setbacks. Check with Sutherland Shire Council or a private certifier before building, especially in bushfire or flood affected areas.
How soon can I build on a new slab?
Most shed builders want at least seven days of curing before fixing frames down. Full design strength takes around 28 days.
Why did my quote come in higher than the per metre guide rates?
Small pours carry the same truck, crew and setup costs as big ones. Difficult access, pump hire, extra excavation on a sloping block and demolition of old concrete all push a quote above the headline per square metre rates.