An AI estimate is a number that looks finished.
It isn't. It is a number that looks like a bid, wins the tender, and then costs the contractor once the work is underway. The danger is not that AI is slow or expensive. The danger is what it cannot see.
On the simplest, cleanest counting an AI tool is useful. The rows below the first are where a tender is won or lost.
The problem is not the price. It is the confidence.
An AI estimate arrives looking complete. Clean lines, a total at the bottom, a professional layout. That is exactly what makes it dangerous.
A hydraulic estimate is not a counting exercise. It is an act of reading a job: what the drawings imply but do not state, where the site fights you, what the authority will demand, which scope hides between the lines. AI prices what is on the page. The cost of a real project lives in what is not on the page, and AI has no way of knowing it is missing.
So the number comes back looking finished, and it is wrong in ways you cannot see by looking at it. You only find out when the job is built.
Same drawings. A number that would have cost the contractor.
We ran an AI-generated hydraulic estimate against our own.
On a recent high-rise residential building in Southport. Identical drawings. Identical brief. The AI number came back looking complete.
A contractor who bid that number would have won the tender, then carried the shortfall on site.
Client and project details withheld. Comparison run on a real tender.
Why the gap is invisible until it is expensive.
We are not going to publish a checklist of what the AI missed. That is the point.
If the gaps were obvious, they would not be gaps. The reason an AI estimate is dangerous is precisely that the missing scope does not announce itself. It is not one big line anyone would notice is absent. It is the accumulated judgment of having priced these jobs before: knowing that this detail implies that cost, that this site condition changes the method, that this authority requirement is coming whether or not it is drawn.
You cannot add what you do not know is missing. That knowledge is the job.
An AI can hand you a number in minutes. It cannot tell you the number is wrong, because it does not know what it did not see. We do, because we have built these jobs, not just counted them.
Where we stand on AI, plainly.
We are not frightened of AI and we are not pretending it has no use. For the simplest, cleanest counting it is a tool like any other. But a tool is not an estimator, and a fast number is not a safe bid. On the complex work, the high-rise, the hospitals, the jobs where the scope decides the margin, the value is entirely in the reading, and that is the part no tool can do for you. When the tender is worth winning properly, you do not want the number that looks finished. You want the number that holds up when the work starts.
Common questions.
Is an AI plumbing estimate reliable?
For simple, clean residential counting it can be adequate. For complex hydraulic work it is risky, because it prices what is drawn and misses the scope that is not. On a recent Southport high-rise an AI estimate came in around 40% below ours for the same drawings, and it looked complete.
Why is an AI estimate cheaper?
Usually because it is incomplete in ways that are not visible. A cheaper number that misses scope is not a saving. A contractor who bids it can win the tender and then carry the shortfall once the job is built.
Does SNZ use AI?
For simple repetitive counting it is a tool like any other. But the value of a hydraulic estimate is in reading the job, not counting it, and that judgment is not something we hand to a tool.
Can I just use AI and add the missing scope myself?
The difficulty is that you cannot add what you do not know is missing. The missing scope in an AI estimate does not announce itself. Identifying it requires having priced these jobs before, which is exactly the judgment a specialist estimator provides.
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Get a number that holds up on site.
Send us your drawings. We will price the whole job and give you a bid you can build to, not a number that looks finished and isn't.
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