Contracts and commercial
HIA, MBA, ABIC, variations, claims.
Contract risk is where most residential builders lose money quietly, through variations that do not get signed, progress claims that miss the statutory window, defects clauses that are read too late, and deposits that are not protected under home building legislation. This pillar covers the standard form contracts used on Australian residential projects: HIA New Homes, HIA Alterations and Additions, MBA GC21, ABIC Simple Works, and the AS 4000 and AS 4902 suites for larger work.
It is for builders, subcontractors, and building designers who enter contracts with clients and subbies and need to understand the key clauses before they sign, not after a dispute. Coverage includes the statutory requirements that override contract terms (security of payment legislation, home building compensation, builder licensing conditions), how to write a variation that will stick, and what the progress payment regime looks like in each state under SOPA.
Chalkline's contract articles are written by someone who has managed real disputes on real projects. The advice is practical: what to do and what not to do, with enough legal context to know when to call a lawyer.
Concept
- concept 9 May 2026ABIC contracts: a builder's guide to Simple Works, Basic Works, and Major Works ABIC contracts are architect-administered building contracts for residential and commercial work. Compare SW-2018, BW-2018, MW-2018 and when to use each.
- concept 9 May 2026Allowances, PC items and provisional sums: what each one means in your contract Allowance, prime cost item and provisional sum: three contract terms builders get wrong. What each means, how margin works, and what NSW and QLD require.
- concept 14 May 2026Design and construct (D&C): a builder's risk primer Design-and-construct is the model where the builder owns the design risk. PI insurance becomes mandatory in NSW from 1 July 2026. State-by-state guide.
- concept 9 May 2026HIA contracts: the full suite explained Complete guide to the HIA residential contract suite: fixed price, cost-plus, state editions (NSW, VIC, QLD, WA, SA), Contracts Online access, and when each applies.
- concept 9 May 2026HIA cost-plus contract: how it works and when to use it How the HIA cost-plus contract works: builder margin, progress claims, NSW and VIC restrictions, and when cost-plus beats fixed-price for residential builds.
- concept 9 May 2026HIA fixed-price contract: builder's guide HIA fixed-price contract for Aussie builders: lump-sum mechanics, PC/PS items, cooling-off periods, deposit limits, mandatory clauses (NSW, VIC, QLD).
- concept 9 May 2026Liquidated damages in building contracts: Australia guide How liquidated damages work in Australian building contracts: penalty doctrine, HIA defaults, calculating a genuine rate, and Security of Payment set-off rules.
- concept 9 May 2026MBA contracts: Master Builders residential contract suite explained Plain-English guide to Master Builders Australia residential contracts: BC4 lump sum, Cost Plus, renovation, ABIC. State editions, key clauses, and how they differ from H
- concept 15 May 2026Novation of design consultants to the builder Novated design: the architect or engineer engaged by the client gets reassigned to the builder at contract execution. Design freeze, change control, PI implications.
- concept 8 May 2026Owner-builder vs licensed builder: contract and legal differences in NSW NSW owner-builder permits, HBCF insurance exclusion, statutory warranties, and how contract obligations differ from a licensed builder under current legislation.
- concept 9 May 2026Prime cost items: supply allowances in residential building contracts Prime cost items cover supply only, not installation. Know the margin rule, reconciliation timing, and how VIC and QLD impose hard disclosure obligations.
- concept 9 May 2026Provisional sum items: scope-undefined work in residential building contracts Provisional sums cover scope-undefined work like earthworks and drainage. Know the margin rule, QLD invoice obligation, VIC penalty, and how true-up works.
- concept 2 May 2026Reading a building contract: what to look for first Plain-English guide for Aussie builders on the clauses to check first in a residential building contract: payment, variations, PC/PS, EOT, LDs, insurance, red flags.
- concept 8 May 2026Retentions clause: how it works and how to negotiate it How Australian building contract retention clauses work: typical 5%, two-stage release at PC and DLP, SOP Act trust rules, and tips to negotiate the terms.
Process
- process 9 May 2026Adjudication under SOPA: the full process from payment claim to enforcement NSW SOPA adjudication: payment claim to enforcement in ~40 business days. Timelines, ANA selection, adjudicator fees, and what if the respondent won't pay.
- process 7 May 2026Extensions of Time (EOTs): how to claim and protect your programme How to claim an EOT under HIA, MBA and ABIC contracts: eligible grounds, notice deadlines, documentation, and the link to liquidated damages.
- process 9 May 2026Progress claims: how to submit, defend, and enforce payment How Australian progress claims work: HIA stages, payment schedule deadlines, NSW SOPA adjudication timelines, and grounds for withholding payment.
- process 9 May 2026Variations process: how to issue, price, and enforce scope changes How to issue, price and enforce variations in Australian residential building contracts. HIA cl 18, MBA cl 14, QBCC rules, and what happens to unsigned variations.
Regulation
- regulation 10 May 2026Domestic Building Insurance VIC: builder's guide to DBI Domestic Building Insurance VIC: mandatory over $16,000. Covers 6 years structural defects. BPC sole provider; first-resort scheme from July 2026.
- regulation 9 May 2026Home Building Compensation Fund NSW: builder's guide to HBCF NSW HBCF: mandatory home warranty for residential work over $20,000. Covers 6 years (major defects) and 2 years if builder becomes insolvent, dies, disappears.
- regulation 10 May 2026QBCC Home Warranty Insurance Queensland: builder's guide to the QHWS QBCC Home Warranty Insurance: mandatory for residential work over $3,300 in QLD. 6 yr 6 month structural, 6-month non-structural, $200k cover. Builder's guide.
- regulation 9 May 2026Security of Payment Act NSW: how to use it NSW Security of Payment Act 1999: payment claims under s13, payment schedules under s14, adjudication under s17, and what residential builders need to know.
- regulation 9 May 2026Security of Payment Act SA: builder's guide to the SA SoP Act SA Security of Payment Act 2009: payment claims, payment schedules, adjudication, residential exclusions, and the 2025 Crown exemption for SA builders.
- regulation 9 May 2026Security of Payment Act VIC: builder's guide to the VIC SoP Act Victoria SoP Act 2002: payment claims, schedules, adjudication via ANAs, domestic building exclusions, and the April 2026 reforms that removed excluded amounts.
- regulation 9 May 2026Security of Payment Act WA: how to use it WA Security of Payment Act 2021: payment claims, payment schedules, adjudication, residential exclusions, and the retention trust scheme explained for builders.
- regulation 9 May 2026Security of payment in Queensland: BIF Act guide for builders and subbies How the Queensland BIF Act 2017 works: payment claims, payment schedules, adjudication timelines, project trust accounts, and residential exclusions explained.