Two renovation projects can have the identical scope and a wildly different experience — and it often comes down to one thing signed at the start: the contract type. In Ontario, renovation work is priced one of two ways, fixed-price or cost-plus, and each hands the budget risk to a different party. Knowing the difference is how you protect yourself.
Fixed-price vs cost-plus at a glance
| Fixed-Price | Cost-Plus | |
|---|---|---|
| How it's priced | One total for a defined scope | Actual costs + a fee (%, or fixed) |
| Who carries budget risk | The contractor | You, the homeowner |
| Cost certainty | High — you know the number | Lower — the total moves |
| Transparency | Line items, but not live costs | Full visibility into every invoice |
| Best when | Scope is well-defined | Scope is unknown or evolving |
How fixed-price works
You and the contractor agree on one total price for a clearly defined scope of work. If the project costs more than expected to deliver that scope, the contractor absorbs it — you're protected. The trade-off: fixed-price only works when the scope is well-defined, and any change you request is handled as a change order with its own price.
Fixed-price is best when your drawings and selections are locked and the scope is clear. It gives you the most cost certainty and the least risk — which is why most homeowners prefer it for a defined renovation.
How cost-plus works
You pay the actual cost of trades and materials, plus a fee — either a percentage (commonly 10–20%) or a fixed management fee. You see every invoice, so it's the most transparent structure, but the total isn't guaranteed — if the project costs more, you pay more.
Cost-plus is best when the scope genuinely can't be pinned down up front — a heritage restoration, a home full of unknowns behind the walls, or a design still evolving during construction. It avoids the inflated "risk padding" a contractor has to build into a fixed price for an uncertain scope.
The danger zone: cost-plus with no ceiling
The contract to avoid is cost-plus with no cap and vague scope. That combination gives the homeowner all the risk and no protection — the budget can climb indefinitely with nothing to anchor it. If a project is cost-plus, insist on either a guaranteed maximum price (GMP) — cost-plus up to a ceiling — or a tight scope and a clear allowance structure.
How to protect your budget either way
- Get it in writing, line by line. In Ontario, any work over $50 legally requires a written contract. Scope, price, and payment terms all belong in it.
- Tie payments to milestones, not the calendar — so you're never far ahead of the work.
- Keep the deposit to 10% or less.
- Define how change orders are priced and approved — in writing, before any change is done.
- On cost-plus, demand a cap (GMP) or a detailed allowance schedule.
Which should you choose?
For a well-defined renovation, fixed-price is usually the safer choice — you know the number and the contractor carries the risk. For a project with genuine unknowns, a cost-plus contract with a guaranteed maximum gives you transparency without an open-ended budget. At Nexon Build we default to fixed-scope, fixed-price contracts — every change documented and approved by you first — because certainty is what lets homeowners actually enjoy the process.
FAQ
What's the difference between fixed-price and cost-plus? Fixed-price locks one total for a defined scope (contractor carries the risk). Cost-plus bills actual costs plus a fee (you carry the risk, but see every invoice).
Which contract protects the homeowner more? Fixed-price, for a well-defined scope. For an uncertain scope, cost-plus with a guaranteed maximum price is the protected middle ground.
Is cost-plus ever the right choice? Yes — when the scope truly can't be defined up front (heritage work, homes full of unknowns, evolving designs). Just insist on a cap.
How big a deposit is normal? No more than 10%, with the rest tied to completed milestones.
Want a contract that actually protects your budget? See how we work as your general contractor, read how to choose a contractor in Toronto, or get a free estimate.