As this series moves through the most common CCDC contract types, our focus will now shift from fixed-price and cost-reimbursable models to contracts designed for projects where quantities are difficult to predict. While CCDC 2 provides certainty through a stipulated sum and CCDC 3 addresses evolving scope through actual-cost reimbursement, the unit price contract (CCDC 4) offers a practical solution when the scope of work is known, but the total volume of that work is not.
Under CCDC 4, the contractor submits pricing based on a fixed cost per unit of work rather than a single lump-sum price. These units could include cubic metres of excavation, tonnes of asphalt, metres of piping, or hours of specific repair services. The final contract value is then determined by multiplying the agreed unit rates by the actual quantities completed during construction.
This structure is commonly used in civil, infrastructure, and maintenance projects where exact quantities cannot be accurately established before work begins. Roadwork, site servicing, utility installation, and rock removal are typical examples. In these situations, the owner can define the type of work required, but subsurface conditions, field measurements, or changing site requirements make total quantities uncertain at tender.
The primary advantage of CCDC 4 is flexibility without sacrificing pricing clarity. Contractors commit to fixed unit rates upfront, giving owners confidence in how costs will be calculated even when final volumes remain unknown. This approach can create a fairer pricing model than forcing contractors to estimate uncertain quantities within a stipulated sum, which often leads to inflated bids to account for risk.
However, because the total contract price depends on actual quantities, owners must carefully manage the risk of cost overruns. Many projects include estimated quantities for bidding purposes, along with adjustment formulas if actual volumes vary significantly from those estimates. Establishing a maximum contract value or spending ceiling can also help protect budgets and support procurement compliance.
Tendering for CCDC 4 often follows a similar low-bid process to CCDC 2, but evaluating bids can be more complex. When multiple unit-price categories are involved, determining the lowest overall bid requires careful review of estimated quantities and pricing assumptions. Accuracy in tender documents is critical to ensure fair comparison and avoid disputes later in the project.
Like other owner-designed contract models, design responsibility typically remains with the owner’s consultant. Clear specifications and measurement standards are essential so both parties understand how units will be calculated, verified, and paid. Ambiguity in these definitions can quickly lead to disagreements over quantities and compensation.
CCDC 4 is most effective when the work itself is straightforward, but the amount of that work cannot be confidently measured in advance. It creates a balance between competitive pricing and practical adaptability, particularly in projects where field conditions drive the final scope.
While CCDC 4 manages uncertainty through measurable units, a different approach is sometimes needed to address uncertainty in project delivery itself. In our next spotlight article, we shift focus to a contract designed for these scenarios: the CCDC 5A, the construction management contract for services,where construction can begin before design is fully complete, and the owner takes on a more active role in managing both risk and project execution.
Looking for a team to take the lead on your next project? At Pulse Construction, we’re committed to doing business with an honest, professional, and competitive approach – without compromising safety or schedules. Contact us today for all of your building needs.
