Building a new home or tackling a major infill project in Calgary is one of the biggest financial commitments you’ll ever make. And the contract you sign with your builder will determine how predictable—or stressful—that journey becomes.

Two common contract types dominate custom home construction in Calgary: Fixed-Price (Lump Sum) and Cost-Plus (Time and Materials) . Both have a place, but they work very differently in our local market, especially given Calgary’s weather, labour availability, and material costs.

Let’s break down exactly how each works, so you can decide which one fits your project.

What Is a Fixed-Price Contract?

With a fixed-price contract, you and the builder agree on a total price before construction begins. That number includes all labour, materials, permits, and builder profit. Unless you approve a formal change order, the price doesn’t change—even if the builder miscalculated or a material jumps in cost.

How it works in Calgary:
Your builder estimates everything in detail: excavation on a sloped lot in the NW, winter heating costs, engineered beams, even Hail-resistant shingles. That estimate becomes the cap.

Advantages of Fixed-Price

Budget certainty – You know the final price (except for changes you request).
Easier financing – Banks and mortgage lenders prefer fixed-price contracts.
Builder bears risk – If ground conditions are worse than expected (common in Calgary’s clay soils), the builder absorbs that cost.

Disadvantages of Fixed-Price

Higher base price – Builders add a contingency (often 10–15%) to protect themselves.
Less transparency – You don’t see exactly what line items cost.
Change orders add up fast – Want to upgrade from vinyl to triple-pane windows? That’s a change order, and it won’t be cheap.

Best for: Homeowners with a hard budget, straightforward lots (e.g., new communities like Seton or Livingston), and a mostly finalized design.

What Is a Cost-Plus Contract?

Cost-plus means you pay the actual cost of construction plus a builder’s fee—usually a percentage (e.g., 15–20%) or a fixed management fee. “Cost” includes materials, subcontractors, permits, and even the builder’s site trailer.

How it works in Calgary:
The builder provides estimates but no fixed total. You get receipts or invoices. If rebar prices spike or a concrete pour needs heating during a February Chinook, you pay the actual cost.

Advantages of Cost-Plus

Full transparency – You see every invoice. No hidden builder markup.
Lower upfront price – The builder doesn’t need a large contingency.
Easier to make changes – Want to change countertops mid-build? No renegotiation needed—you just pay the difference.

Disadvantages of Cost-Plus

No price cap – Your home could cost significantly more than expected.
Builder has less incentive to save money – With a percentage fee, higher costs mean higher builder profit (unless you negotiate a fixed fee).
Requires more trust & time – You need to review invoices regularly. Not ideal for first-time builders.

Best for: Experienced homeowners, complex infills (e.g., a sloped Mount Royal lot with a walkout basement), or projects where the design isn’t fully finished.

Which One Is Safer for Calgary Homeowners?

For most people: Fixed-price is safer.

Calgary’s construction environment has wildcards: Chinook-related foundation stress, spring runoff delays, labour shortages, and fluctuating lumber prices. A fixed-price contract puts those risks on the builder—not you.

But there’s a catch. Some builders respond to fixed-price contracts by:

Picking lower-grade materials to protect their margin
Arguing over change orders for everything
Adding so many exclusions that the “fixed” price doesn’t cover much

So if you choose fixed-price, get a very detailed scope of work attached to the contract. Every light fixture, cabinet brand, and insulation R-value should be listed.

Cost-plus makes sense if:

You’re building a luxury home with many custom, unpredictable elements
You trust your builder completely (and have references to prove it)
You have a large contingency fund (20%+ of estimated budget)
You or a project manager can review invoices weekly

4 Questions to Ask Before Signing Either Contract

What’s excluded? (Landscaping? Appliances? Permit fees? Utility connections?)
How are change orders priced? (Fixed markup or actual cost plus fee?)
Who manages overages? (In cost-plus, you need an invoice review process.)
Is the builder using CHBA Calgary’s standard contract? (A good baseline for local accountability.)

Call to Action

At Raynow Homes, we offer both contract models—but we always start with a conversation about your risk tolerance, timeline, and budget. Before you sign anything, we’ll walk you through a detailed estimate specific to your Calgary lot.

Footer note: This blog is for informational purposes. Always consult a Calgary construction lawyer before signing any contract over $10,000.

Insights

Fixed-Price vs. Cost-Plus Contracts: Which One Protects Your Calgary Home Build?