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Hidden cost checklist: questions to ask a modular builder before you sign

From Modular Living Australia — the independent knowledge base Last updated: 8 Oct 2026

Tell the tool what you are building and tick any site conditions that apply, such as a sloping block, no sewer connection or bushfire-prone land. It generates a list of the cost items a factory quote may leave out, grouped by stage of the build, with a question to send each builder in writing. Print it or copy it as text, and send the same list to every builder so their quotes can be compared on the same scope.

A quote for a factory-built home usually describes what happens inside the factory. What happens on your land — earthworks, transport, craneage, service connections, approvals and finishing — may be quoted separately, quoted later, or not quoted at all. One published builder guide notes that transport and installation are sometimes included only within a set radius of the factory, which is why the list of inclusions and exclusions matters more than the headline figure when comparing quotes.^[1]

The practical consequence is that two quotes can differ by a large margin and still describe the same house, because they describe different scopes. This page does not attempt to tell you what anything costs. It generates the list of things to ask about, phrased as questions you can send to a builder and get an answer against.

Build your checklist §

Answer as much as you know. The list below rebuilds as you go. Items shown with a green tag appear only because of a site condition you ticked.

How to use the result §

Send the list to each builder you are comparing and ask for the answer in writing against every line, marked one of three ways: included, excluded, or a provisional sum. The third is the one to watch — a provisional sum is an allowance rather than a fixed price, and it can move once the actual work is scoped.

Where an item comes back as excluded, the follow-up question is who is responsible for arranging it, not only who pays. Some excluded items are things a homeowner can organise; others require a licensed trade, a network operator or a council application, and leaving them unassigned is how a project stalls between the factory and the slab.

Two quotes are only comparable once both have been marked up this way. Until then, a lower headline figure may simply describe less work.

Warranty cover for the factory-built stage §

The checklist includes a line about statutory warranty cover because this is one area where factory-built housing is treated differently from conventional construction, and differently again between states. Two published positions illustrate the point.

In Queensland, the regulator states that the Queensland Home Warranty Scheme may apply to tiny homes and other prefabricated or flatpack homes, but only in respect of on-site residential construction work including installation — it does not cover off-site manufacturing.^[2] The practical reading is that the factory stage and the site stage may not sit under the same protection.

In Victoria, Home Warranty commenced on 1 July 2026 and applies to eligible domestic building contracts signed on or after that date, for work valued above A$20,000; policies issued under the previous Domestic Building Insurance arrangements continue under that earlier scheme.^[3] Which scheme applies therefore depends on when the contract was signed.

Positions in the other states and territories are not covered here. Rather than infer them from the two above, ask the builder directly which scheme applies to your contract, and verify the answer with the relevant state regulator before signing.

What this tool does not do §

It does not estimate anything. It contains no prices, no rates per square metre and no allowances, because a credible figure for site works depends on the specific block and cannot be generated from a set of tick boxes.

It does not assess a builder. A builder whose quote excludes many of these items is not necessarily worse than one whose quote includes them; a quote that excludes site works honestly and says so may be more useful than one that buries an optimistic allowance. What matters is that the exclusions are visible before the contract is signed.

It does not replace advice on your property. Council requirements, overlays and covenants vary between and within local government areas, and can override general expectations about what is required.

Nothing entered on this page is stored or transmitted. Reloading clears every answer, so print or copy the list before you leave.

References §