The 5 Key Types of Construction Contracts for Capital Projects

Jamie Cerexhe
Jamie Cerexhe
March 19, 2024
The 5 Key Types of Construction Contracts for Capital Projects

Various construction contracts are available for those seeking to execute a capital project in the construction industry. As an asset owner, it is essential to have a thorough grasp of the appropriate type of contract for your specific project. It depends on what you want to build and how you want to do it.

Construction contracts serve as the backbone for defining project scope, costs, timelines, and the professional relationship between project stakeholders. A lot of money is on the line, so selecting a suitable contract can dramatically influence the success of capital projects, thus ensuring project owners and contractors navigate their projects efficiently and to mutual benefit so everyone wins.  

Carrolton Farms Branch Independent School District is an asset owner delivering capital projects.
Carrolton Farms Branch Independent School District is an asset owner delivering capital projects.

1. Fixed-Price Contract or Lump-Sum Contract

The Fixed-Price Contract, often called a Lump-Sum Contract, provides a predefined cost for project completion, irrespective of actual expenses incurred. Popular examples of this contract type is Australia's AS4000 and AS2124.

Parties (in our scenario, asset owner and contractor) agree on a fixed price for the entire project or phase. This contract type shines in scenarios where project deliverables and scopes are clear from the get-go. It instills a layer of financial predictability for the project owner, simplifying budget management tasks significantly.

Ideal for capital projects with a well-documented scope, fixed-price contracts are the go-to for initiatives where changes are minimal. Projects like constructing new buildings or establishing infrastructure facilities exemplify the practical application of this contract, given their predictable nature.

To enhance the adaptability of fixed-price contracts, integration with separable portions agreements is common, enabling project components to be segmented and managed independently. Moreover, novation deeds are critical in maintaining contractual integrity, even when transitioning between contractors, preserving the predetermined financial commitments.

2. Cost-Plus Contract

Embracing uncertainty in the scope, the Cost Plus Contract pays contractors for the actual cost of the work/materials plus an agreed-upon profit margin. This model is particularly valuable for projects where the full scope unfolds over time or is expected to evolve, offering a blend of flexibility and oversight.

Suited for pioneering or uncertain capital works, such as innovative construction methods or the incorporation of cutting-edge technology, the cost-plus contract allows for seamless scope adjustments without dispute. Projects like developing research facilities or sustainable building initiatives often leverage this contract for its adaptability.

3. Unit Pricing Contract

A construction contract based on Unit Pricing is excellent for capital projects with identifiable units of work or material requirements, setting a price per unit and offering unparalleled clarity and control over variable project elements.

This contract is particularly beneficial for repetitive or quantifiable tasks, as seen in infrastructure or utility projects. Think of linear tasks such as laying pipes, draining, or tracking. It promotes transparency and affords the flexibility needed to adjust to actual work volumes, ensuring that payment reflects the true scope of work completed.

Capital projects, such as extensive roadworks or utility system upgrades, often utilize unit pricing contracts to capitalize on the precise accounting of tasks and materials. This contract type can seamlessly integrate with fixed-price contracts for a balanced approach to project financial management, catering to fixed and variable project dimensions.

Stormwater retention projects is one examples of capital projects under a Unit Pricing Contract.
Stormwater retention projects is one examples of capital projects under a Unit Pricing Contract.

4. Time and Materials Contract

The Time and Materials Contract provides a flexible framework for projects where initial scope clarity is unclear, compensating contractors based on labor hours and material costs. This contract type is a great way to get started quickly. It can be essential for managing projects with evolving, careful, or uncertain scopes, ensuring financial fairness by aligning costs directly with work performed.

Optimal for specialized or minor projects with unpredictable scopes, such as custom renovations or repairs, it ensures that payments are made for actual work done, aligning costs with project realities. Further, capital projects involving restoring historical structures or bespoke installations often rely on time and materials contracts, which require time and care to execute the work. These contracts may be supplemented with cost-plus agreements for broader project components, balancing scope flexibility and cost oversight.

5. Design-Build or Design & Construction Contract

The Design-Build Contract, often called a Design & Construction contract, or simply 'D&C,' merges design and construction phases under a single agreement to be executed by the contractor. This contract brings design under the contractor's responsibilities, fostering a cohesive project development process that can yield time and cost efficiencies based on the contractor's expertise. This approach is particularly effective for projects requiring rapid execution or for those where design and construction processes are deeply intertwined.

The design-build contract encourages a collaborative project environment and is ideal for fast-paced capital projects or those with integrated design and construction needs, such as custom industrial facilities. This enhances efficiency and spurs innovation, potentially leading to more effective project outcomes.

Mastt's HQ in Sydney was completed by a contractor using a D&C Contract.
Mastt's HQ in Sydney was completed by a contractor using a D&C Contract.

Capital works projects, including new campus developments or industrial plant constructions, benefit from the comprehensive approach provided by design-build contracts. These projects might also incorporate fixed-price contract elements to maintain cost management throughout the project lifecycle.


Selecting the most suitable construction contract is a critical decision that significantly affects the success of any capital project. Each contract type offers unique advantages and is best suited for specific project conditions. By carefully evaluating the project's scope, complexity, and risk profile, project owners and contractors can choose an agreement that meets project objectives and fosters a successful partnership and project completion.

Disclaimer: While Mastt is dedicated to offering valuable industry insights, it's important to note that we are not legal experts. Therefore, our content should not be interpreted as legal advice. We encourage readers to exercise discretion and seek personalized guidance from qualified legal professionals.

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