Flat Pack Granny Flats: Compare Kit Scope and Project Costs

Flat pack granny flats supply a building package for assembly on site, but the package isn’t the whole project. Compare the specified structure, inclusions and documentation before comparing prices. Then price the approvals, foundations, services and finishing work that you must arrange separately.

We don’t rank a timber, steel or panel system as universally cheapest. Nor do we multiply a kit price by a fixed number to predict the finished cost. Both shortcuts conceal differences in scope that matter on an Australian backyard site.

What does the supplier actually include?

Request an itemised schedule rather than relying on “complete kit”. Ask whether it covers the frame, roof, cladding, windows, insulation, internal linings, doors and fixings. Confirm quantities and specifications as well as the presence of an item.

If the photograph shows a finished kitchen, deck or bathroom, check whether those components are in the contract. A presentation image can show an optional configuration. You’ll need the written schedule to compare the package with another supplier’s offer.

A finished module is a different supply method from a flat-pack kit. Our kit versus modular comparison explains the responsibility questions without treating factory completion as permission to occupy.

Use dated prices with their exclusions

On 3 October 2026, Wide Span Homes’ Cabin page showed a 60 m² design with a 22.5 m² veranda at $32,300, or $39,400 for the stated cyclonic option. Those are advertised kit figures, not a finished dwelling quote for your land. Recheck the current offer, GST treatment, delivery area and inclusion schedule with the supplier.

The example is useful because it identifies a product and supply stage. It doesn’t establish the average Australian kit price or a budget for assembly. Our 60sqm cost guide separates that starting price from the rest of the project.

Ask for a written quote with an expiry date. If the supplier offers optional windows, insulation or cladding, compare the same configuration across quotes. Keep unknown amounts marked as unpriced so they don’t disappear from the total.

Check documentation before ordering

Have the responsible practitioner identify the building classification and approval pathway for the intended use. Ask which engineering documents the supplier provides and which site-specific design you must commission. A standard engineering package may need information about the address, ground conditions or proposed installation.

Energy performance also needs a project-specific check. The NCC energy provisions include different compliance methods, with jurisdictional variations. Don’t accept a generic star claim as proof that your chosen orientation and glazing comply.

Ask who resolves a documentation gap if the assessor requests changes. Establish that responsibility before dispatch, especially when the kit supplier and site builder are different businesses.

Plan assembly, delivery and licensed work

For an owner-build, check the permit and training requirements in your state. Then compare the assembly instructions with your available skills, equipment and time. A supplier helpline can explain a component; it doesn’t take over your construction responsibilities.

Have the delivery contractor confirm access, unloading and storage needs. Materials left on site may require protection before assembly. Agree who carries the risk of damage and what happens if the site isn’t ready on the delivery date.

Obtain quotes for the work you won’t perform. Plumbing and electrical work need the appropriately licensed trades, and the project requires its applicable inspections and completion documents. Use our owner-builder checklist to allocate those tasks.

Frequently asked questions