15
Questions that reveal a real builder
1
Number that matters most: blower-door result
Tarion
Ontario new-home warranty — verify standing
The builder you choose matters more than the lot, the plan, or the finishes. A great plan built badly is a bad house; a modest plan built well is a great one. The trouble is that every builder's website says the same things — quality, craftsmanship, energy efficiency — and the words tell you nothing. What tells you something is the answer to a specific question, and whether the builder can give it without flinching.
These fifteen questions are the ones we'd ask if we were hiring a builder ourselves. For each, there's a good answer and a vague one, and learning to hear the difference is most of the skill. A builder who knows their numbers answers fast and specifically. A builder who's hand-waving gets philosophical. You're listening for the difference.
We've grouped them by what they reveal: performance, the people and the paper, and how the relationship actually runs. None of them require you to be an expert — just to listen for a number where there should be one.
Performance: What's Actually Behind the Walls
1. What's your average blower-door test result?
The single most revealing question you can ask. A builder who tests every home can tell you their average ACH50 from memory. One who can't — or who doesn't test at all — has just told you their commitment to performance is words, not numbers. A typical Ontario code build is around 3.5 ACH50; we guarantee 1.5 or better and average 0.85.
2. Do you use continuous exterior insulation?
Listen for a specific assembly, not a yes. A real answer names the material and thickness — for example, two inches of exterior mineral wool outside the sheathing — and can explain why it matters. "We use good insulation" is not an answer.
3. What windows do you install as standard?
Double-glazed is code-minimum. Triple-glazed is the high-performance standard, and a builder who installs it as standard rather than an upgrade is telling you where they sit. Ask whether triple-pane is included or extra.
4. How do you ventilate the house?
A tight house needs mechanical ventilation. The right answer involves an HRV or ERV with real filtration (MERV-13 or better) and — critically — commissioning, meaning someone measures and balances the airflows after install rather than just hanging the box on the wall.
5. What's your plan for radon?
Ontario soils produce radon, the leading cause of lung cancer in non-smokers. A builder with a plan installs active sub-slab mitigation during construction and tests after occupancy. A builder without one will tell you to "test it later," which means retrofitting at several times the cost.
6. How do you heat and cool the home?
The current best answer for Ontario's climate is a hybrid system — a cold-climate heat pump for efficiency most of the year, with a gas furnace taking over on the coldest days. A builder reaching only for a basic furnace-and-AC package isn't thinking about your operating cost.
Those first six questions are really one question asked six ways: does this builder build to a verifiable performance standard, or to whatever the code minimum allows? If you want the full background before you ask them, our 2026 Building Science Guide covers each of these systems in depth, and the article on airtightness explains why the blower-door number is the one to anchor on.
"A builder who tests every home knows their average blower-door result without looking it up. If that question produces a pause, you've learned what you needed to know."
The People and the Paper
7. Are you registered and in good standing with Tarion?
Every new home in Ontario must be built by a Tarion-registered builder and comes with the statutory new-home warranty. Verify the builder's registration and licence yourself on the Home Construction Regulatory Authority's public registry — don't take it on faith.
8. Can I speak with three recent clients?
A good builder hands over references without hesitation, including a recent one and ideally one whose home is a couple of years old, so you can ask how it's held up. Reluctance here is a flag.
9. Can I see a home you built that's a few years old?
New homes all look good at handover. The test is how a home looks after a few winters. A builder proud of their durability will happily show you one.
10. Who's actually on site, and how often?
Ask who supervises the build day to day and how involved the principals are. On a custom home you want to know the people running it, not just the people who sold it.
11. What warranty do you offer beyond Tarion?
Tarion is the floor — one, two, and seven-year statutory coverage. Some builders back specific systems, like the HVAC package, with their own longer warranty. Ask what's covered, by whom, and for how long.
12. What certifications do you hold?
Credentials like CHBA Net Zero builder status or Energy Star certification aren't marketing badges — they require third-party verification of how you build. Ask which ones the builder actually holds versus aspires to.
How the Relationship Runs
13. How do you handle change orders?
Changes happen on every custom build. What matters is the process: a good builder prices changes in writing before doing the work, so you approve the cost first. "We'll sort it out at the end" is how budgets blow up.
14. What does your quote actually include?
Ask what's in the number and what isn't. Are allowances for finishes realistic or lowballed to make the bid look good? Is servicing in or out? A transparent builder lines this out so there are no surprises; a vague quote is a future argument.
15. How do you communicate during the build?
A year-long project lives or dies on communication. Ask how often you'll get updates, who your point of contact is, and how decisions get documented. The answer tells you what the next twelve months will feel like.
The last three questions aren't about building science at all — they're about whether you'll enjoy the year you spend together. A builder who prices changes up front, quotes transparently, and communicates clearly is a builder who respects your money and your time. You can learn more about how we work on our team page, and the FAQ answers a lot of these directly for our own process.
"Build cost is one number. The builder is every other number. Ask the fifteen questions, listen for specifics, and let the vague answers disqualify themselves."
Key Takeaways
The blower-door average is the single most revealing question — a real builder answers it from memory.
For envelope and mechanicals, listen for specific assemblies and numbers, not adjectives like "quality" and "efficient."
Verify Tarion registration yourself, and ask for references including a home that's a few years old.
Certifications like CHBA Net Zero require third-party verification — ask which ones the builder actually holds.
On process, the change-order and quote-transparency answers predict whether your budget will hold.
A builder who can't give specifics on performance, paper, or process has answered the real question.
