QC1 contract (HIA Queensland new homes)

The QC1 is the Housing Industry Association (HIA) Queensland standard contract for new home construction. It is the dominant residential new-home contract in Queensland volume building, published by HIA Qld and aligned with the Queensland Building and Construction Commission Act 1991 (Qld) Schedule 1B (regulating residential building contracts in Qld) and the QBCC home warranty insurance scheme. The contract is structured for fixed-price new-home builds with prime cost items and provisional sum mechanisms for selections and unknowns.

Where it sits in the HIA Queensland contract family:

Contract	Purpose
QC1	New home construction (fixed price, prime cost, provisional sum)
QC2	Cost-plus new home construction
QC3	Alterations and additions
QC4	Owner-builder construction
QC5	Minor works

QC1 is the most-used by volume in Queensland because most residential new-home builds in Qld are fixed price.

Key features of the QC1:

Feature	Detail
Contract sum	Fixed price at signing (with variation mechanism)
Prime cost items	Allowance for items not yet selected (e.g. tiles, taps)
Provisional sums	Allowance for unknowns (e.g. site works)
Stage payments	Standard residential stage schedule (deposit, slab, frame, lockup, fixing, PC)
Variations	Written, signed, before work starts (per Schedule 1B)
Defects liability period	12 months (standard QBCC-aligned period)
QBCC home warranty	Insured under the QBCC scheme; premium typically passed through
Cooling-off period	5 business days for the client (per Schedule 1B)
Practical Completion	Defined; triggers PC payment and starts defects period

QBCC Schedule 1B compliance (mandatory features):

The QBCC Act 1991 Schedule 1B sets mandatory requirements for residential building contracts in Qld. The QC1 includes:

Deposit cap: maximum 5% of contract value (QBCC limit).
Stage payment schedule: cannot be front-loaded; must align with actual work value.
Cooling-off period: 5 business days.
Variations in writing: signed before work starts.
Defects liability: minimum 12 months for residential.
Insurance disclosure: QBCC home warranty premium disclosed.
Client information requirements: standard disclosure forms.

A non-Schedule 1B-compliant contract is potentially unenforceable by the builder; clients can argue the contract is void or modified.

Prime cost items vs provisional sums:

Type	When used	Example
Prime cost (PC) item	When the item is known but the SELECTION isn’t	Tile allowance $50/m² (client picks at selection stage)
Provisional sum (PS)	When the work is known but the COST isn’t	Site works PS $10,000 (actual cost confirmed once excavated)

Both adjust the contract sum up or down based on actual cost. The QC1 standardises how these are handled (notice required, evidence required, time impact).

Common builder issues:

Loading the deposit above 5%: Schedule 1B breach; client can demand refund.
Stage payments front-loaded: Schedule 1B requires payments to reflect actual work value; backloading is also a breach.
Verbal variations: Schedule 1B requires written, signed. Verbal variations unenforceable.
PC item not adjusted at selection: client picks more expensive tile; builder forgets to invoice the difference; PC mechanism fails.
PS work done at higher cost without notice: builder discovers site works are more expensive but doesn’t notify client; can’t recover the excess.

For builders:

Use the current QC1 version from HIA Queensland; the contract is updated periodically as legislation changes.
Set PC and PS allowances generously at quote stage; under-estimating creates variation friction later.
Issue written variations for every change, signed before work starts.
Maintain QBCC home warranty currency for every Qld residential build.
Brief clients on the cooling-off period at contract signing; document delivery for the 5-day clock.

Also known as: HIA QC1, HIA Queensland new homes contract, QC1 new home contract.

Category: Contracts / Queensland / residential.

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