Written by: Luke Cheverie
Reviewer: Editorial Team
Replacing windows and doors is one of the best investments you can make in your home. Done right, it improves comfort, lowers energy bills, and adds lasting value for decades to come.
A quick search for "Best Window and Door Replacement Company in the Greater Toronto Area or Hamilton" returns hundreds of options. The good news? Finding the right one doesn't require a PhD in windows. It’s about asking the right questions and knowing what a straight answer sounds like.
How To Choose A Window and Door Company
Here are five questions to bring to every consultation to help guide you through the process and make an informed decision.
Do you manufacture your own windows, or are you a reseller?
What exactly does a window & door warranty cover?
Are your windows ENERGY STAR® certified? What's their ER rating?
What material are your windows made of? How does it perform in Canadian winters?
How do you handle a service call after installation?
Question 1: Do You Manufacture Your Own Windows and Doors, or Are You a Reseller?
Choose a company that manufactures and installs its own windows and doors. This means better quality control, direct warranty accountability, and no middleman markup between you and the product.
Three types of companies typically exist: manufacturers, resellers/installers, or both.
Manufacturers usually design and build their windows and doors in-house. Resellers/installers purchase windows and doors from a third party, often selling them under the supplier's name. Keep in mind that some companies, such as Nordik , are both manufacturers and installers.
The difference matters because it affects who is accountable when something needs fixing. When something goes wrong, a manufacturer can fix it and stand behind it. A reseller can only call their supplier and hope for the best.
It also affects
Quality control — who's overseeing production?
Price — resellers add markup on top of the manufacturer's markup
Warranty accountability — unless it’s a manufacturer direct warranty, accountability can be ambiguous depending on the reseller’s promise
Question 2: What Exactly Does A Window and Door Warranty Cover?
A strong window and door warranty should cover product, installation, and labour. It should also be non-prorated, clearly define its duration, and be written in plain English. Avoid vague “lifetime” warranties that exclude labour or reduce coverage over time.
If it takes more than one page to explain or has fine print, that's worth questioning. Another red flag is "our warranty is industry-leading" without specifying what it covers. Vague warranty language is not accidental.
Before you sign anything, here’s what to look for.
Related:
Question 3: Are Your Windows ENERGY STAR® Certified? What's Their ER Rating?
In Canada, window energy performance is measured by ER. Natural Resources Canada (NRCan) calculates this value and uses it to determine ENERGY STAR® certification. It combines three performance factors into one optimized rating.
U-factor - how well the window resists heat loss
Solar Heat Gain Coefficient, or SHGC - how much solar energy passes through the glass
Air leakage rate
Choosing a window with the highest ER value generates the maximum energy-efficiency benefit all year-round.
Almost all of our Nordik standard configuration windows are ENERGY STAR® Most Efficient certified . This means every product meets the performance standard designed specifically for Canadian climate conditions. The casement and awning double-pane windows are consistently performing at ER 40. The great thing is that the windows often outperform the competitors' triple-pane products. You get the kind of efficiency you'd expect to pay more for, but without the high cost.
Can I Verify Your Product Performance?
You can verify any company's claims through the NRCan Searchable Product List and the NFRC (National Fenestration Rating Council). Both publish independent, third-party data.
Question 4: What Material Are Your Windows Made Of? How Does It Perform In A Canadian Winter?
Look for windows made with solid-core mPVC (microcellular PVC) rather than standard hollow vinyl. Solid-core frames hold up better through Ontario's extreme temperature swings, deliver more stable long-term thermal performance, and allow for slimmer frames that let in more natural light.
Solid-core mPVC, Nordik’s exclusive RevoCell® technology is engineered with billions of microscopic air bubbles throughout the frame. Each one acts as a buffer, moderating the temperature as it tries to move through the material. The more bubbles, the more moderation — which means less of the cold outside becomes the cold inside.
In contrast, the industry standard is hollow vinyl (PVC). While they are widely used, they are actually less energy-efficient, which can affect your energy bills. Why? Because it’s hollow, it’s like having only a handful of large chambers doing the same job. Fewer buffers means more temperature transfer and less thermal stability, especially through Ontario's seasonal temperature extremes.
Here's the difference and why it matters for Canadian homeowners:
Question 5: How do you handle a service call after installation?
A trustworthy window and door company has a dedicated service team with a clear response time commitment and a process that treats post-installation calls with the same care as a new job.
Ask the company directly: "Walk me through what happens if I have an issue after installation." A company that's genuinely invested in after-care will be specific without hesitating.
Pro Tip
Always check what the warranty covers. Coverage of common issues should include hardware adjustments, weather-stripping wear, and seal-integrity checks are all part of the deal, not afterthoughts. Nordik has a 25-Year No-Bull warranty, which includes parts, labour and service. No fine print, no surprises.
Look for:
A dedicated service line or team — separate from the sales line, so your call isn't competing with new quote requests for attention
A clear response time commitment — an actual estimated time frame, not "as soon as possible"
Real examples of post-install calls they handle regularly — a company with a functioning service department can rattle these off without thinking about it.
Pro Tip
Always keep a copy of your warranty documents. If you ever need to make a claim, written proof is your strongest protection.
Bonus: How Does the Sales Experience Feel?
A trustworthy company sends a consultant, not a closer. They ask about your home before talking about their products. They explain your options instead of steering you toward one.
Good Questions to Ask When Replacing Windows. Here's How We Answer Them.
These questions won't just help you find a good window company. They'll help you understand what you're actually buying.
Good windows and doors, installed correctly, by a company that stands behind the work, will perform for decades to come and increase the comfort, energy efficiency, and resale value of your home.
How Does Nordik Answer These Questions?
Manufacturer? Yes. Our team handles everything from production to installation to after-care service. We design and build our own custom doors and RevoCell® windows all made in Canada, by Canadians for Canadians.
Warranty? Our 25-Year "No-Bull" Warranty is one page with no fine print. It covers product, installation, and service, is non-prorated, and fully transferable.
Energy efficiency? Almost all of our standard configuration RevoCell® windows are ENERGY STAR® Most Efficient certified. Our performance data is listed publicly on NRCan and NFRC.
Window Frame material? RevoCell® is solid-core mPVC , our exclusive technology. Slimmer frames, more glass, and better thermal stability through Ontario winters, not just the first one.
After-installation service? We have a dedicated service team with a clear response process.
Forty-plus years and 100,000+ Ontario homes later, we've answered these questions thousands of times and our answers are always the same. Why? Because we believe in happy customers and treating your home like it's our own.
Frequently Asked Questions
What is a good Energy Rating (ER) for windows in the GTA?
In Canada, a window's Energy Rating (ER) is the primary measure of performance in our climate. Windows rated with an ER ≥ 34 and a U-factor of ≤ 1.22 W/m²·K qualify for ENERGY STAR® certification. Windows with ER ≥ 40 with a U-factor of ≤ 1.05 W/m²·K earn ENERGY STAR® Most Efficient status.
Almost all of Nordik Windows and Doors' standard configurations, including casement, hung and slider, hit an ER of 40 in double-pane and ER 47 in triple-pane, earning ENERGY STAR® Most Efficient designation. This is higher than most competitors' on the market. Whether Canadian weather is trying to freeze you in February or melt you in August, these windows are built for both.
What should I look for when choosing a window and door company in Toronto?
Look for a window and door company that manufactures its own product, has its own installation team, and offers a clearly written warranty covering product and labour. Also, don’t be afraid to ask for third-party certification data.
What does a typical window warranty coverage include in Canada?
A strong window and door warranty covers three things without exception: the product, the installation, and the labour to fix either. It doesn't shrink over time (non-prorated), it transfers to the next owner if you sell, and it fits on one page with no fine print or a law degree to decode it.
How many quotes should I get for window and door replacement in the GTA?
Getting 2–3 quotes is a smart idea. Compare value to price and look at the detailed description, including the door and window specifications (frame material, ER rating, glass type) and installation type. Also consider what's covered under the warranty .
About Nordik
Nordik Windows & Doors manufactures and installs windows and doors for Ontario homeowners. Every product is custom-built in Canada, every installation is handled by Nordik's certified crews, and every job is backed by the 25-Year No-Bull Warranty, covering product, parts, labour, and installation with no fine print.