The 5% Deposit Cap: A Quick Way to Spot a Dodgy Deck Builder

There is one fast, simple test that filters out a lot of bad deck builders in South Australia, and most homeowners do not know it exists. It is the deposit.

If a builder asks for a 25 percent deposit, or 40 percent, or "half upfront to cover materials", they are breaching South Australian law. Here is what the rules actually say and why the deposit is such a useful warning sign.

The 5% deposit cap

Under the Building Work Contractors Act 1995 - the same law that requires a BWC licence for building work over $20,000 inc GST - the deposit a builder can take for residential building work is capped at 5 percent of the contract price.

That is the legal maximum. Not a guideline, not a norm - a cap. A builder who demands more than 5 percent upfront, before work has started, is breaching the Act. On a $25,000 deck, the legal maximum deposit is $1,250. A builder asking for $6,000 upfront is well outside the law.

Why this is such a useful test

The deposit cap is useful precisely because it is simple and the builder cannot disguise it. A homeowner cannot easily tell a sound frame design from a corner-cutting one, or seasoned timber from green. But anyone can hear "I need 30 percent before I start" and recognise it against a 5 percent cap.

A builder who demands a large upfront payment is showing you something. At best they are working outside the rules they should know. At worst, large upfront deposits are how cash-only operators take a homeowner's money and disappear before doing the work - one of the most common decking horror stories in South Australia.

A licensed, reputable builder works within the cap because they are run as a proper business with cash flow, and because they know the law.

What else the contract rules require

The deposit cap is one of several protections that come with building work over $20,000 inc GST. A written contract is mandatory - standard ones include the HIA or Master Builders SA decking contract. Building indemnity insurance is mandatory, protecting you if the builder dies, disappears or becomes insolvent before finishing, and the builder must give you proof of it before work starts.

A builder who wants to work on a handshake, cash, no contract, and a big deposit is offering you none of these protections.

GST is another quiet signal

While you are checking the deposit, check the GST. Residential deck quotes are normally GST inclusive. A builder who quotes "ex GST" or wants to be paid cash to avoid GST is a warning sign - a builder turning over enough to do decks should be GST-registered, and a cash-to-dodge-GST arrangement leaves you with no proper invoice and no recourse.

Put it together

Three quick checks filter out most bad deck builders before you ever assess the quality of their work. Is the deposit at or under 5 percent? Is there a written contract with proof of building indemnity insurance? Is the quote properly GST inclusive with a real invoice?

A builder who passes all three is operating properly. One who fails any of them is telling you something. When you compare 3 quotes through Decking Adelaide, every builder is BWC-verified - but knowing the deposit cap means you can run the test yourself, every time, on any builder.