Understanding Quantum Meruit and Variations in Construction Contracts

When it comes to construction contracts, two terms often surface: quantum meruit and variations

 Quantum meruit, a Latin term meaning “as much as he has earned”, is a legal principle that allows a person to claim reasonable compensation for services rendered or work done when no contract exists, or when a contract has been terminated prematurely. In the context of construction, quantum meruit claims often arise when a builder has performed work outside the scope of the original contract, and seeks to recover the fair value of that work.

 On the other hand, variations refer to changes or additions to the agreed scope of works in a construction contract. Variations can be requested by either party and may involve changes in design, materials, or construction methods. They are common in construction projects due to unforeseen circumstances or changes in the owner’s requirements.

However, variations can lead to disputes, especially when they are not properly documented or agreed upon. This is where quantum meruit claims come into play, providing a potential avenue for builders to recover costs for variations not formally agreed upon. Understanding the interplay between these two concepts is key to managing risks and avoiding disputes in construction contracts.

Quantum Meruit: A Legal Remedy for Unpaid Work

Quantum meruit acts as a legal safety net for unpaid work. This principle comes into play when a builder has performed work that falls outside the original contractor’s scope, and no agreement was made for this additional work. Quantum meruit allows the builder to claim a reasonable sum for this work, ensuring they are not left out of pocket. However, making a successful quantum meruit claim is not straightforward. It requires meeting certain conditions, such as proving the owner knew the work was outside the contract and that the builder expected payment.

Variations in Construction Contracts: An Overview

Variations are a common occurrence in construction contracts. They refer to any changes or additions to the original scope of work agreed upon in the contract. According to Clause 18 of the HIA NSW Residential Building Contract, variations must be in writing and signed by both parties. If not properly managed, variations can lead to disputes, especially when there’s disagreement over the cost or extent of the additional work, making understanding of this concept crucial for all parties involved.

Key Components of a Successful Quantum Meruit Claim

In New South Wales, the application of quantum meruit in construction contracts has been shaped significantly by case law. Two cases, in particular, provide valuable insights: 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.

Based on these cases, a successful quantum meruit claim requires several key components:

  1. The work performed must fall outside the original contract’s scope.
  2. The homeowner must have actual knowledge of the variation as it’s being done.
  3. The homeowner understands that the work being done is outside the contract.
  4. The homeowner must know that the builder expects payment for the work as a variation to the contract.
  5. The builder must provide evidence that the claimed amount was fair value for the work performed.

Practical Steps for Builders to Claim Quantum Meruit

For builders, claiming quantum meruit involves several practical steps:

  1. Document Everything: Keep detailed records of all work performed, especially work that falls outside the original contract’s scope. This includes time spent, materials used, and any additional costs incurred.
  2. Communicate Clearly: Ensure the homeowner is aware of any variations as they occur. This includes explaining why the variation is necessary, how it affects the project, and the additional costs involved.
  3. Get Written Agreement: As per Clause 18 of the HIA NSW Residential Building Contract, variations should be in writing and signed by both parties. If the owner refuses to sign, document their refusal and your attempts to get their agreement.
  4. Fair Pricing: The claimed amount must represent the fair value of the work performed. This can be supported by market rates, quotes from other builders, or costs of materials and labour.
  5. Seek Legal Advice: Quantum meruit claims can be complex. It is advisable to seek legal advice to understand your rights and obligations, and to ensure your claim is valid and enforceable.

Remember, each case is unique, and what works in one situation may not work in another. Always seek professional advice when dealing with quantum meruit claims.

Get Expert Construction Contract Review and Advice

Expert contract review and advice is just a step away. Connect with us to explore how we can assist with your construction law needs.

Get Your HIA Contract Reviewed Now

Step 1: Simply fill out this form and upload your contract.

Step 2: We’ll review it and return to you with a fixed fee quote.

Minimise construction risks on cost, time, and quality.
Get Home Building Contract Review and Advice now.


Navigating quantum meruit claims and variations in construction contracts can be complex, but understanding these concepts can help protect your interests and ensure a fair outcome. Remember, every situation is unique, and professional advice is invaluable. As a solicitor and construction lawyer with over 10 years of experience specialising in construction law, I can provide expert advice tailored to your specific circumstances. Whether you’re a builder or a homeowner, I can help you understand your contractual and legal rights, manage risks, and negotiate contracts. Don’t navigate these complexities alone. Reach out for a consultation and let’s ensure your construction project is on solid legal ground.