Does SNZ use AI for estimating?

Yes. We use AI for the repetitive counting of fixtures and pipe runs, which is fast and reliable. We do not rely on it for pricing judgment, scope interpretation or site conditions, which is where AI misses cost.

Why is an AI plumbing estimate cheaper?

Because it is usually incomplete. On a recent Southport high-rise an AI estimate came in around 40% below ours for the same drawings, because it omitted labour build-up, an acoustic lagging subcontract, and under-scoped preliminaries. A cheaper number that misses scope costs the contractor once the job starts.

What does AI miss in hydraulic estimating?

On the projects we have tested it on, AI reliably handles the counting but misses the scope that is not literally drawn. On a recent Southport high-rise it omitted the labour build-up, an acoustic lagging subcontract, and under-scoped preliminaries. What it misses varies by job, which is exactly why complex work needs a human estimator who has priced it before.

Is a human estimator still worth it if AI is free?

For simple, clean residential work AI may be enough. For complex hydraulic work, high-rise, hospitals and rail, the scope AI misses is worth many times the cost of a proper estimate. The value is in the judgment, not the counting.

AI vs Human Estimating

We use AI too. For the boring part.

We use AI for the repetitive counting, then our estimators price the scope it misses. We tested it on a real project. What we found is below, and it is why contractors bring the complex jobs to us.

Real project · 7-level residential · Southport QLD

Same drawings. A quarter of a million dollars apart.

We ran an AI-generated hydraulic estimate against our own on a recent seven-level residential building in Southport. Identical drawings, identical scope brief.

~40%

The AI estimate came in roughly 40% below our figure for the same job

$250k+

The gap between the two estimates, in scope the AI never priced

A contractor who bid the AI number would have won the job, then discovered the hole once the work was underway. The difference was not the rates. It was the scope the AI never built.

Where the gap actually came from

Not clever pricing. Missing scope. Four things the AI estimate left out or under-built, every one of which a contractor still has to pay for on site:

Labour it never built

The AI priced items but never built the crew-day labour underneath them. On a job of this size that is the single largest line, and it was simply not there.

The acoustic lagging subcontract

A required acoustic lagging package, priced as a subcontract in our estimate, was absent from the AI version entirely. On a residential high-rise that is a five-figure omission on its own.

Preliminaries and project management

Site establishment, QA, testing, commissioning and project management were collapsed into a single small allowance, under-scoped by tens of thousands against what the job actually requires.

Wastage and demobilisation

Material wastage and demobilisation, standard cost lines on any real project, did not appear in the AI estimate at all.

None of these are exotic. They are the ordinary realities of building the job. AI misses them because it prices what it can see on the page, not what the work actually takes.

Our position on AI, plainly

We are not against AI, and we are not going to pretend it is useless. We use it ourselves for the repetitive counting that used to eat an afternoon. But a fast number is not a safe number. When we ran it against our own estimate on a real seven-level building, the AI produced a figure that looked complete and was not. The value of an estimate is knowing what the drawings do not show, and that is the part we do not hand to a machine, or to anyone else.

Get an estimate you can actually bid on

Send us your drawings. We will price the whole job, flag the scope gaps, and give you a number that holds up when the work starts.

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