5 Questions to Ask Your Concreter Before Signing a Contract (Adelaide Guide)

Concrete is permanent. Once it is poured and cured, fixing problems means grinding, cutting, or full removal — any of which costs thousands. The best way to protect yourself is to ask the right questions before you hand over a deposit.

Here are the 5 questions every Adelaide homeowner should ask before signing with a concreter.

1. Are You Licensed Under the SA Building Work Contractors Act?

In South Australia, any building work valued over $12,000 — including concrete driveways, slabs, and patios — requires the contractor to hold a Building Work Contractors (BWC) licence issued by Consumer and Business Services SA (CBS SA).

Ask for the licence number and verify it yourself at cbs.sa.gov.au.

What to look for:

• Licence class: should include "Building Work Contractor" covering concrete/civil works
• Licence status: Active (not suspended or expired)
• Name on licence must match the business name on the quote

Why it matters: An unlicensed contractor cannot legally perform regulated building work in SA. If something goes wrong — cracking, settlement, flooding — you may have no legal recourse and no access to the SA Home Building Fund (the statutory insurance scheme for licensed work).

Opal SA Construction holds BLD 317725 — fully active, verified on CBS SA.

2. What Concrete Specification Are You Quoting?

The quality of a concrete driveway or slab depends entirely on what goes into it. Ask your concreter to specify in writing:

Component	What to ask for	Why
Concrete strength	25 MPa minimum, 32 MPa for pool surrounds	Strength determines load capacity and durability
Reinforcement mesh	SL72 (standard) or SL82 (reactive clay sites)	Prevents cracking under load and ground movement
Roadbase depth	100 mm minimum compacted DGB20	Prevents slab sinking
Concrete thickness	100 mm minimum for driveways	Below this, concrete cracks under vehicle loads
Moisture barrier	0.2 mm PE sheet	Prevents subsoil moisture migration into slab

If a concreter says "standard mix" without specifying MPa, or "reinforced" without specifying the mesh grade, push for specifics. These details should appear on the written quote.

3. Who Does the Physical Work — Your Own Crew or Subcontractors?

Some Adelaide concreters quote the job, then hand it to a cheaper subcontractor you have never met. This is legal, but it creates accountability gaps:

• The person who quoted you may never appear on site
• The subcontractor may not follow the agreed specification
• If something goes wrong, the principal contractor blames the sub

Ask directly: "Is this your own employed crew, or do you subcontract the pour?"

If they use their own crew, ask how long the crew members have been with them. Experienced, stable teams produce more consistent results than casual labour assembled job-by-job.

At Opal SA Construction, every job is completed by our own trained crew under Javed's supervision — no subcontracting.

4. What Does Your Warranty Actually Cover, and for How Long?

Concrete workmanship warranties in Australia vary from zero (informal operators) to 10 years (licensed, reputable contractors). Ask for the warranty in writing and confirm:

• What is covered: Structural cracking? Surface delamination? Settlement? Colour fading?
• What is excluded: "Normal" hairline cracks? Staining? Tree root damage?
• Duration: How many years?
• Process: How do you make a claim? Is it in writing?

Red flags:

• "Lifetime warranty" with no written terms — often meaningless
• Warranty only valid "if you don't seal it yourself" — legitimate contractors seal it for you
• Verbal warranty only — get it in writing

Opal SA Construction provides a 10-year workmanship warranty on all structural concrete work, in writing, as part of the contract.

5. What Do Adelaide's Soil Conditions Mean for This Specific Job?

This question separates contractors who understand local conditions from those who pour the same slab everywhere in Australia.

Adelaide has significant soil variability — from stable Class A coastal soils near the beach to highly reactive Class H2 clay in the northern suburbs. A competent Adelaide concreter should be able to tell you:

• What soil classification is likely at your address
• Whether that affects the slab thickness, mesh grade, or roadbase specification
• Whether you need an engineer's design (required for Class E expansive or P problem soils)

If a concreter says "it doesn't matter" or cannot explain what AS 2870 means, they may be applying a one-size-fits-all specification that does not account for your site.

Suburbs with the most reactive soils in Adelaide:

• Northern: Salisbury, Elizabeth, Para Hills, Gawler, Angle Vale, Munno Para
• Southern: Morphett Vale, Reynella, Hallett Cove, Christies Beach
• Eastern fringe: Some areas of Modbury and Golden Grove

Bonus: Red Flags to Watch For

• Quote is significantly cheaper than all others (usually means something is being cut)
• No written quote — quote is verbal or on a scrap of paper
• Requests cash payment in full upfront
• Cannot show a licence number or insurance certificate
• Does not mention soil conditions, reinforcement, or concrete strength
• Pressure to sign "today only" pricing

Summary Checklist

Before signing, tick all 5 boxes:

☐ Licence number provided and verified at cbs.sa.gov.au

☐ Concrete specification in writing: MPa, mesh grade, roadbase depth, thickness

☐ Confirmed: own crew, not subcontractors

☐ Written workmanship warranty (years, scope, claims process)

☐ Adelaide soil conditions discussed and accounted for in specification

Request a written quote from Opal SA Construction — licence BLD 317725, 43 Google reviews, 10-year warranty.

Internal links to include:

• How to Choose a Concreter in Adelaide
• Concrete Driveways Adelaide
• Concrete Slabs Adelaide
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