Background of MBA Contract (BC4)

The Master Builders Association Head Contract Residential Building (BC4) is a standardised New South Wales (NSW) contract. Tailored for residential construction projects, this contract outlines the legal obligations, rights, and procedures for builders and homeowners, ensuring clarity and compliance within the industry.

Understanding Variations in Construction Contracts

Variations in construction contracts are changes or adjustments to the original scope of work agreed upon in the contract. These changes can be complex and multifaceted, and understanding them is essential for builders and homeowners. Here’s a closer look at the key aspects;

Definition of Contract Variation

A contract variation in construction refers to any alteration, addition, or omission to the initially agreed scope of work. It encompasses changes in design, materials, quality, or other aspects of the contract. Variations must be properly documented and consented to, ensuring alignment with the contract’s terms and legal compliance. It is also important to note that variations can impact the scope, cost, and timeline of a project.

Reasons for Contract Variation

Contract variations arise for various reasons, including unforeseen site conditions, regulation changes, client requests, or design modifications. Understanding the underlying causes helps manage these changes effectively.

The Contract Variation Process

The contract variation process under the MBA Contract (BC4) is a structured approach that ensures clarity and compliance. It involves:

  1. Identification: Recognising the need for a change.
  2. Documentation: Detailing the variation in writing, including the scope, cost, and time.
  3. Approval: Obtaining consent from all parties, often requires signatures.
  4. Implementation: Executing the variation, as agreed upon.
  5. Adjustment: Modifying the contract price or construction timeline, as necessary.

This process safeguards the interests of both builders and homeowners, providing a clear framework for handling variations and aligning with legal requirements in NSW.

Clause 14 of MBA Contract (BC4): A Detailed Analysis

Clause 14 of the Master Builders Association Head Contract Residential Building (BC4) provides a comprehensive framework for dealing with variations. This clause is pivotal for builders to ensure transparency and compliance. Here’s a detailed analysis of Clause 14:

Overview of Clause 14

Clause 14 of the MBA Contract (BC4) meticulously outlines the procedures for managing variations in construction contracts. It defines what constitutes a variation, the process for documentation and approval, and the implications for construction costs.
Main SubjectClause Number under MBA Contract (BC4)Explanation
Execution of Additional WorkClause 14(a)(i)

Execution of additional work under Clause 14(a)(i) of the MBA Contract (BC4) refers to any extra tasks beyond the original contract scope. 

It must be properly documented and agreed upon, ensuring that the additional work aligns with the contract’s terms and the parties’ mutual understanding.

Decreases, Omissions, and Changes in WorkClause 14(a)(ii)

Clause 14(a)(ii) of the MBA Contract (BC4) covers the decreases in, or omissions from the work. 

These variations may involve reducing the scope, omitting certain tasks, or altering materials and quality. 

Proper management ensures the project remains aligned with the contract and the parties’ expectations.

Builder’s Consent and DocumentationClauses 14(c) and (d)

Under Clause 14(c) and 14(d) of the MBA Contract (BC4), the Builder’s consent is required for variations, and it must not be unreasonably withheld. 

Any agreed variation must be detailed in writing and signed by both parties, ensuring clear documentation and alignment with the contract’s terms.

Value of Variations and Cost CalculationClauses 14(e) to (i)

Clause 14 of the MBA Contract (BC4) emphasises the importance of determining the value of variations. 

The Builder must notify the Owner of the variation’s value (Clause 14(e)) and detail the cost calculation. 

For additional work, the cost includes labour, subcontractors, materials, and third-party expenses (Clause 14(g)-(i)). 

The actual cost saved is deducted from the contract price (Clause 14(f)) for decreased or omitted work. 

This clear framework ensures transparency and fairness in pricing variations, aligning with both parties’ expectations and maintaining the integrity of the contractual relationship.

Directing the BuildeClause 14(j)

Clause 14(j) underscores the importance of clear communication within the construction process. 

It specifies that neither the homeowner nor any appointed representative can provide instructions to the Builder’s workers or subcontractors regarding the project. 

All directions must be in written form and given to the Builder, ensuring accurate and documented communication to prevent misunderstandings and disputes. 

This requirement promotes transparency and accountability, contributing to the smooth execution of construction works.

Quantum Meruit Claims in NSW

Quantum meruit, meaning “what one has earned” in Latin, is a legal principle allowing a party to claim reasonable payment for services rendered or work performed outside a contract’s scope. 

Conditions for Quantum Meruit Claims based on Case Laws

Two significant cases, Durastyle Homes Pty Ltd v Gosling; Gosling v Durastyle Homes Pty Ltd [2022] NSWCATCD 106 and Nayak v Rockwall Constructions Pty Ltd [2017] NSWCATAP 18, have shaped the understanding of quantum meruit claims in NSW. These rulings outlined the five essential components for a successful quantum meruit claim, in that:

  1. The homeowner must know of the variation as they were being done;
  2. The homeowner must know that the work is outside the contract;
  3. The homeowner must know that the builder expected to be paid for the work as variation to the contract; and 
  4. The builder had provided evidence that the amount claimed was fair value.

These cases serve as a vital reference for builders for establishing a quantum meruit claim.

Practical Application in Construction Contracts

Quantum meruit claims have practical applications in construction contracts, mainly when variations occur without proper agreement. Builders must understand these principles to navigate complex situations, ensuring fair compensation for extra work. Proper documentation and clear communication with the owner are vital to applying quantum meruit in construction contracts.
Compliance with Clause 14 of MBA Contract (BC4) A Builder's Guide to Variations


Navigating the complexities of variations and quantum meruit claims under the Master Builders Association Head Contract Residential Building (BC4) for NSW requires a deep understanding of the contractual clauses and their legal principles. From defining variations to understanding the provisions of Clause 14, builders must be equipped with the knowledge and tools to effectively manage these aspects of construction contracts.

Quantum meruit claims, in particular, present unique challenges and opportunities. Understanding the conditions, relevant case law, and practical applications can empower builders to assert their rights and manage risks.

As a solicitor and construction lawyer with more than 10 years of experience specialising in construction law, I regularly advise homeowners and builders regarding their contractual and legal rights. I represent clients in the tribunals of NSW, Australia, and all courts of competent jurisdiction. My expertise in Quantum Meruit Claims and Variations under the MBA Contract (BC4) has guided many in understanding their contract rights, risks, and obligations and in negotiating and amending contracts to reflect their intentions.

If you are a builder seeking to understand your legal rights and obligations regarding quantum meruit claims and variations, don’t hesitate to contact me. Together, we can navigate the complexities of construction law, ensuring that your interests are protected, and your construction projects are successful.