Types of Construction Contracts: Lump Sum, Cost-Plus, and Unit Price Explained
Before a single beam goes up or a single crew shows up on site, one decision shapes the whole project: how the contractor gets paid. That decision comes down to the type of contract you sign, and getting it right matters just as much as picking the right contractor in the first place. Yet most owners spend far more time thinking about who will do the work than how the payment structure will actually work.
Understanding the types of construction contracts available isn’t complicated once someone explains it in plain language, which is what this guide sets out to do. We’ll walk through the main contract types used on Canadian industrial projects, what each one is good for, and where the risk sits in each case. If you’re planning a build, a shutdown, or an ongoing maintenance contract, this is worth knowing before you sign anything.
Why the Types of Construction Contracts Matter Before You Even Pick a Contractor
Every construction contract answers the same basic question: who takes on the risk if something costs more or takes longer than expected? The types of construction contracts differ mainly in how they answer that question. Some put almost all the risk on the contractor. Others share it with the owner. None of them are wrong — they just fit different situations.
Picking the wrong one for your project doesn’t usually blow things up right away. It shows up later, as disputes over change orders, arguments about what was included in the price, or a contractor pricing in so much extra risk that the “fixed price” wasn’t actually a good deal. Knowing the options up front avoids most of that.
In Canada, many of these contract structures follow standard forms published by the Canadian Construction Documents Committee (CCDC), a national body that develops widely used templates for construction agreements. You don’t have to use a CCDC form, but a lot of Canadian contracts are built on that structure, so it’s useful to know the names.
Lump Sum Contracts: One Price, Fixed in Advance
A lump sum contract, also called a stipulated price contract, is the simplest of the types of construction contracts to explain: the contractor agrees to do the whole job for one fixed price. The owner knows the total cost before work starts. If the job costs the contractor more than planned, that’s on the contractor. If it costs less, the contractor keeps the difference.
This type works best when the scope is clear and unlikely to change — a well-defined steel erection job, for example, where the drawings are finished and everyone knows exactly what’s being built. The tradeoff is flexibility. Any change to the plan after signing usually means a change order, which can slow things down and sometimes leads to disagreement about what the original price was supposed to cover.
Cost-Plus Contracts: Pay for What It Actually Costs
A cost-plus contract works the opposite way. The owner pays the contractor’s actual costs — labour, materials, equipment — plus an agreed fee on top, usually a percentage or a fixed amount. There’s no single locked-in price for the whole job.
This structure makes the most sense when the scope isn’t fully known at the start. Emergency repairs, breakdown work, and projects where the full extent of the problem only becomes clear once work begins are good examples. You can’t put a fixed price on fixing something you haven’t fully assessed yet, and cost-plus lets work start right away instead of waiting for a detailed estimate that might be wrong anyway.
The tradeoff here is the opposite of lump sum: the owner carries more of the cost risk. Good cost-plus contracts usually include some kind of cap or a “guaranteed maximum price” so costs can’t run away entirely, along with clear rules on what counts as a reimbursable cost.
Unit Price Contracts: Pay by the Piece
A unit price contract sets a fixed price for each unit of work — per linear foot, per tonne of steel, per cubic yard — rather than one price for the whole job. The final cost depends on how many units actually get used, measured once the work is done.
This fits projects where the general scope is known but the exact quantities aren’t locked down until the work is underway — earthwork, certain types of repair work, or projects where conditions in the field might change what’s actually needed. It gives the owner price certainty on a per-unit basis while staying flexible on total quantity.
Design-Build: One Contract for Design and Construction
Design-build contracts combine design and construction responsibility under one contractor, rather than the owner hiring a designer and a builder separately. The contractor takes the project from concept through completion, often allowing design and construction to overlap instead of happening one after the other.
This approach tends to speed up projects and reduces the back-and-forth that can happen when a separate designer and contractor don’t fully understand each other’s plans. It works well when the owner wants a single point of accountability for the finished result, rather than managing two relationships and hoping they line up.
Which Type of Construction Contract Fits Industrial Work?
On industrial sites — mining facilities, grain terminals, processing plants — the right contract type usually depends on what kind of work is happening.
Planned shutdowns and greenfield builds with clear drawings and a defined scope are often a good fit for lump sum pricing, since the work is well understood before anyone shows up.
Emergency breakdowns and unplanned repairs almost always lean toward cost-plus, simply because nobody knows the full scope until the damage is actually assessed.
Ongoing maintenance contracts, where the scope varies month to month, often end up as a mix — sometimes unit pricing for routine, measurable work, with cost-plus terms built in for anything unexpected that comes up along the way.
This connects directly to something we covered in our post on general contractors versus subcontractors: the contract type and the contracting structure are two different decisions that work together. Who’s holding the contract matters. How that contract prices the work matters just as much.
A Few Questions Worth Asking Before You Sign
Whichever type of construction contract you’re considering, a few questions help avoid problems later:
- What exactly counts as included in the price, and what triggers a change order?
- If it’s cost-plus, is there a cap, and what counts as a reimbursable cost?
- Who owns the risk if site conditions turn out different than expected?
- How are delays handled, and by whom?
A contractor who can walk through these questions clearly, before you sign anything, is usually a good sign they’ve handled this kind of project before.
Frequently Asked Questions About Types of Construction Contracts
What is the most common type of construction contract in Canada?
Lump sum, also called stipulated price, is the most widely used contract type in Canada for projects with a clearly defined scope. It’s the standard structure behind many CCDC contract forms.
Which contract type is best for emergency repairs?
Cost-plus is usually the better fit for emergency or breakdown work, since the full scope isn’t known until the problem is assessed. It allows work to start quickly instead of waiting on a fixed-price estimate.
Can a project use more than one contract type?
Yes. Larger or ongoing projects sometimes combine approaches — for example, unit pricing for predictable, repeatable work alongside cost-plus terms for anything unplanned that comes up during the contract.
What’s the difference between lump sum and unit price contracts?
A lump sum contract sets one total price for the entire scope of work. A unit price contract sets a fixed price per unit of work, with the total cost depending on the actual quantity completed and measured.
Choosing the Right Fit for Your Project
None of the types of construction contracts is universally better than the others. The right one depends on how well the scope is understood before work starts, how much risk each side is willing to carry, and what kind of project you’re actually running.
Credence Construction works across all of these contract structures on mining, agricultural, and industrial projects throughout Saskatchewan, Alberta, Manitoba, and Western Ontario — from planned greenfield builds to emergency breakdown response. If you’re planning a project and want to talk through which contract structure actually fits it, call us at 306-786-7000.
