Key takeaways
- Residential building work over $20,000 inc GST requires a BWC-licensed contractor (threshold up from $12,000 on 10 November 2025)
- Unlicensed building work over the threshold carries fines up to $20,000 (individual) or $100,000 (company)
- An unlicensed builder means no building indemnity insurance - you have no recourse if the work fails
- Verify any builder's BWC licence free on the CBS public register before signing anything
When a BWC licence is required
The Building Work Contractors Act 1995 (SA) is the law that governs who can carry out residential building work in South Australia. It is administered by Consumer and Business Services SA, known as CBS.
The Act requires that any residential building work over $20,000 inc GST be performed by a person or company holding a current Building Work Contractor's licence. This threshold increased from $12,000 to $20,000 on 10 November 2025. For decking, that explicitly includes new deck construction, major deck rebuilds or replacements, pergola, gazebo and verandah construction over the threshold, and pool-surround decking and pool-zone work. Most decks above a small ground-level build cross the $20,000 threshold, so most deck work in SA is licensed building work.
What a licence actually means
A Building Work Contractor's licence is held in the name of an individual or company, and it specifies the trade categories the holder is licensed for - for example carpentry, or general building. A current licence indicates that, at the point of issue, the holder met experience, qualification and insurance requirements.
Licences are not permanent. They expire and must be renewed annually, which is why checking a licence is current - not just that one once existed - matters. A builder operating on a lapsed licence is, for that work, an unlicensed builder.
Building indemnity insurance and the deposit cap
For any residential building work where the contract price exceeds $20,000 inc GST, building indemnity insurance is mandatory under the BWC Act. This insurance protects you, the consumer, if the builder dies, disappears, or becomes insolvent before completing the work. The builder must arrange and pay for the cover and provide proof to you before any work starts.
The Act also caps the deposit. The deposit for residential building work is limited to 5 percent of the contract price. A builder demanding 25 percent or more upfront before work starts is breaching the Act - it is a clear warning sign. Building work over $20,000 inc GST must also use a written contract, such as the HIA or Master Builders SA decking contract.
The cost of using an unlicensed builder
Using an unlicensed builder for work over the threshold is the single biggest consumer-protection failure in SA decking. The consequences are severe and they fall on you, the homeowner, not just the builder.
There is no building indemnity insurance, so if the builder disappears or the work fails you cannot recover your deposit or remediation costs through CBS or SACAT. Your house insurance can decline rot, leak or structural claims tied to unlicensed work. The deck may fail council inspection at sale, requiring full replacement. And the unlicensed builder themselves faces fines up to $20,000 for an individual or $100,000 for a company, with civil compensation orders also possible.
How to verify a builder's licence
Verifying a builder's licence in South Australia is free, fast and public. Consumer and Business Services maintains an online licence register. Search the builder's name or company on the CBS public register and a current Building Work Contractor's licence will show, along with its categories and status.
Do this before you sign anything, every time. A licensed builder will give you their licence number without hesitation. Decking Adelaide verifies every builder's BWC licence on the CBS register before connecting them with you - but you can and should confirm it independently. See also our guide on deck permits in South Australia, which covers whether your deck needs council approval.
BWC Licensing (SA) - frequently asked questions
A Building Work Contractor's licence is required for any residential building work over $20,000 inc GST in South Australia, under the Building Work Contractors Act 1995. The threshold increased from $12,000 on 10 November 2025. For decking, that covers new deck construction, major rebuilds, pergolas and verandahs over the threshold, and pool-surround decking.
Search the builder's name or company on the Consumer and Business Services public licence register online. A current Building Work Contractor's licence will show, with its categories and status. The check is free and public. Do it before signing anything - a licensed builder will give you their licence number without hesitation.
An individual carrying out building work over the threshold without a licence faces fines up to $20,000, and a company up to $100,000, with civil compensation orders also possible. Beyond the builder's penalty, the homeowner loses building indemnity insurance cover and any recourse through CBS or SACAT if the work fails.
Building indemnity insurance is mandatory under the BWC Act for residential building work where the contract price exceeds $20,000 inc GST. It protects you if the builder dies, disappears or becomes insolvent before finishing the work. The builder must arrange and pay for the cover and give you proof before any work starts. An unlicensed builder cannot provide it.
The Building Work Contractors Act caps the deposit for residential building work at 5 percent of the contract price. A builder demanding 25 percent or more upfront before work starts is breaching the Act, and it is a clear warning sign. Building work over $20,000 inc GST must also be done under a written contract.
Ready for real quotes?
We connect you with 3 independent, BWC-verified Adelaide deck builders. Free, no obligation.
Get 3 Free Quotes