The Power of Certainty: Fixed Price Contracts in Residential Construction

A fixed price contract answers one question a homeowner cares about more than almost any other: what is this going to cost me. The builder commits to completing a defined scope for a set amount, and that amount does not move unless the scope does. For a family financing a custom home or a major renovation in Vancouver, that certainty is often worth more than shaving a small margin off the total.

The word doing the work in that sentence is defined. A fixed price is only as solid as the information it was built on, and that is where most disappointment with this contract type actually comes from.

What a fixed price contract commits to

A fixed price contract, sometimes called a lump sum contract, is an agreement where the builder delivers a specific scope of work for a predetermined amount. The price is built from the drawings, specifications, and selections that exist on the day the contract is signed. The builder prices trades against that documentation, adds overhead and margin, and takes on the risk that their estimate within that scope was right.

Compare that to a cost-plus contract, where you pay the actual cost of construction plus an agreed fee and see the invoices as they arrive. Under cost-plus you carry the cost variance. Under fixed price the builder carries it, inside the defined scope, and you pay for that transfer of risk in the number.

• One contract value agreed before construction starts
• A scope defined by complete drawings, specifications, and selections
• Estimating and productivity risk inside that scope sits with the builder
• Changes to the scope are handled through written change orders, priced separately
• The price does not respond to the builder's actual costs coming in high or low

Where the certainty actually comes from

The certainty is not created by the contract. It is created by the documentation the contract points at, and the contract simply records it.

For us to price a fixed contract with confidence, we need architectural drawings that are complete, structural engineering finished, mechanical and electrical layouts coordinated, an energy model confirming the design meets the BC Energy Step Code step the municipality requires, and finish selections resolved to the point where a trade can price a specific product rather than an allowance. That is a lot of work to complete before signing, and it is the real trade you are making.

When a builder offers a firm number against a 60 percent drawing set, they have not removed uncertainty. They have priced their guess at it, either by loading the number with contingency or by writing exclusions that surface later as change orders. Both are worse for you than doing the design work first.

Allowances are the soft spot

An allowance is a placeholder amount for something not yet selected: tile, plumbing fixtures, lighting, appliances, cabinetry hardware. Every fixed price contract has some. The question is how many, and how honestly they were set.

Read the allowance schedule before you read anything else in the contract. Ask what product each allowance was based on, whether it covers supply only or supply and installation, and what happens if your selection comes in above it. An allowance set at a number nobody could actually buy at is how a low fixed price stops being fixed. We would rather show you a higher, honest number at signing than a comfortable one that grows every month.

What a fixed price contract does not protect you from

Three things sit outside the price, and all three are worth naming before you sign.

Changes you make. A fixed price contract does not remove change orders, it defines them. Ask for a different window package or move a wall after the contract is signed and the price adjusts. That is the system working as designed, and the contract should set out exactly how a change gets priced and approved in writing before the work happens.

Concealed conditions on a renovation. Older Vancouver housing stock hides things: knob-and-tube wiring, undersized joists, rot behind cladding, asbestos in flooring and drywall compound in anything built before 1990, which brings WorkSafeBC's asbestos requirements into scope with their own abatement procedures. Nobody can price what nobody could see. A well-written renovation contract says clearly how concealed conditions are handled rather than pretending they will not appear.

Changes imposed from outside. A municipal reviewer's comment, a revised engineering requirement, or a code interpretation that changes an assembly is not the builder's estimating error. The contract should distinguish between the builder's risk and the owner's, in writing, rather than leaving it to be argued later.

Why lenders like a fixed price

Construction financing works off draws tied to progress, and a lender's appraiser needs a defined project value to work against. A single contract amount with a complete drawing set makes that appraisal straightforward. A cost-plus arrangement with an open-ended total requires the lender to take a different view, and that usually means more documentation from you.

Coordinate the draw schedule in the construction contract with your lender's advance schedule before you sign either. When the contract's milestones and the lender's inspection points do not line up, the gap becomes your cash-flow problem, and it is easier to fix on paper than during framing.

The holdback is part of the payment structure

Whatever the contract type, BC law governs part of how money is held. Under section 4 of the Builders Lien Act, the person primarily liable on a contract must retain a holdback equal to 10 percent of the value of the work or material as it is actually provided. Section 20 gives subtrades and suppliers 45 days after the certificate of completion to file a claim of lien, and section 8 sets the holdback period at 55 days, after which the holdback can be released if no lien has been filed.

That holdback exists so an unpaid subtrade cannot register a lien on your title after you have paid the general contractor in full. It is not a discretionary retention you can waive to be helpful.

Where fixed price is the right call

New construction on a clean site with a finished design is the natural home for a fixed price contract. The unknowns are mostly resolved, the drawings support real pricing, and the builder can commit without inflating the number to cover blind spots.

It also suits homeowners whose budget genuinely has no headroom. If exceeding a specific figure would derail the project or the financing, buy the certainty and accept the front-loaded design work that makes it real. And it suits anyone who would find monthly cost variance stressful, which is a legitimate reason to choose a contract type.

Where it is the wrong call

A major renovation of a century-old Kitsilano or Mount Pleasant house is the classic mismatch. Too much is hidden behind finishes to define a complete scope, so either the builder loads the price heavily or the contract fills with exclusions that make the number less fixed than it looks. Cost-plus with disciplined open-book reporting usually serves those projects better, and we make that case in our post on cost-plus contracts.

It is also the wrong call when the design is not done and the owner will not wait. Forcing a fixed price onto an unfinished design does not create certainty, it just moves the argument to a later date when it costs more to resolve.

There is a hybrid that suits a lot of Vancouver projects: run cost-plus through design and pre-construction while selections settle, then convert to a fixed price once the drawings and specifications are complete and priced. Flexibility while you need it, certainty by the time it matters.

Reading the contract before you sign it

Whatever the structure, check the same things. Confirm the builder holds a Licensed Residential Builder licence, which section 14(1) of the Homeowner Protection Act requires for anyone carrying on the business of a residential builder in BC, and verify it on the BC Housing public registry rather than taking a website's word for it.

Confirm the new home is registered for 2-5-10 home warranty insurance, which section 22(1) requires before a new home is built. Read the change order procedure, the allowance schedule, the schedule and any delay provisions, and the exclusions list. The exclusions list is the part people skip and the part that decides what fixed actually means on your project.

A fixed price contract is a promise about a scope. If you want the promise to hold, spend the time defining the scope. That work happens before signing or it happens during construction, and it is far cheaper the first way. We argue the same point from a different angle in why you should select your builder early.

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