Window and door replacement is one of the most common home improvement projects — and one of the most aggressively marketed. Homeowners are targeted by door-to-door salespeople, high-pressure showroom pitches, and advertising that blurs the line between what windows actually do and what the sales process promises. The result is that many Canadians spend significantly more than they need to, or end up with a product that underperforms what they were promised.

The questions in this guide cut through the noise. They apply whether you’re replacing a single drafty window, upgrading all the windows in a 1970s bungalow, or installing a new front door. They’re organized by stage — before hiring, at the quote stage, and through installation and warranty.

“Window replacement is the trade I’ve seen the most homeowners regret — not because the windows were necessarily bad, but because they were sold something they didn’t fully understand at a price that was much higher than necessary. The questions that protect you are the ones about the specific product specifications, the energy ratings, and what’s actually included in the warranty. Those questions make the sales process much more honest.”

— Theresa Huang, certified window and door installer and building envelope consultant with 16 years of experience in residential fenestration in the local area

Before You Call Anyone

Back view of unrecognizable craftsman using cordless screwdriver and assembling window while screwing metal hinge during renovation works in apartment

What problem are you actually trying to solve?

The answer to this question should drive every decision that follows. The most common reasons homeowners replace windows and doors are:

Drafts and air leakage. Often caused by failed weatherstripping or deteriorated caulking — not necessarily the window itself. In some cases, a simple weatherstrip replacement or recaulking is all that’s needed.

Condensation between panes. Fogged or cloudy glass indicates a failed insulating glass unit (IGU) seal. In many cases, the IGU can be replaced without replacing the entire window frame.

Heat loss and high energy bills. Legitimate in older single-pane or failed double-pane windows — but the energy savings from window replacement are often overstated in sales pitches.

Operational failure. Windows that won’t open, close, or lock — often fixable with hardware replacement or adjustment.

Aesthetics or renovation. The most honest reason and one that requires no justification.

Understanding your actual problem helps you avoid paying for a full replacement when a repair would do.

Is this a repair or a replacement?

Not every window problem requires a full replacement. Ask a contractor to assess your specific situation honestly before assuming replacement is necessary. A contractor who immediately recommends full replacement without considering repair options is prioritizing revenue over your interests.

Questions to Ask Before Hiring

Wooden door against narrow passage with parquet and closet in contemporary house in daylight

Are you a licensed contractor and registered business?

Window and door installation doesn’t carry its own trade licence in most regions the way plumbing or electrical does — but the contractor should hold a valid business registration, carry proper insurance, and ideally hold manufacturer certifications for the products they install.

Ask for the company’s business registration number, tax-registration number, and any manufacturer certifications they hold.

What a good answer looks like: A registered business with a verifiable tax-registration number, manufacturer certification for the products being installed, and membership in a relevant professional association.

Are you certified to install the products you’re recommending?

Most major window manufacturers — Pella, Andersen, Marvin, JELD-WEN, Durabuilt, Gentek — offer installation certification programs. Certified installers are trained in the manufacturer’s specific installation requirements, which is often necessary to qualify for the full manufacturer warranty.

Ask whether the installer is certified for the specific product being recommended.

What a good answer looks like: Confirmed certification for the product being installed, with documentation available.

Do you carry liability insurance and workers’ compensation coverage?

Window and door installation involves ladders, heavy materials, and work at heights. Workers’ compensation coverage protects you if a worker is injured on your property. Liability insurance covers any damage to your home during installation — a broken window during removal, a damaged exterior finish, or water infiltration if flashing isn’t properly installed during the gap between removal and installation.

For a full breakdown: Questions to Ask a Window and Door Contractor About Licensing and Insurance

How long have you been installing this specific product?

Installation quality varies significantly between experienced and inexperienced crews. Ask specifically how long the crew has been installing the product being recommended, and ask for references from jobs using the same product.

Questions About the Product

What are the energy performance ratings for these windows?

Windows sold should carry ENERGY STAR certification and an NFRC (National Fenestration Rating Council) label with specific performance metrics:

U-factor: Measures heat loss. Lower is better. For Canadian climates, look for U-factor of 1.22 W/m²K or lower (ENERGY STAR your country requirement for Zone 2 — most regions).

Solar Heat Gain Coefficient (SHGC): Measures how much solar heat passes through the glass. In your country, a moderate SHGC (0.25–0.40) is often appropriate — allowing some passive solar gain in winter while limiting summer overheating.

Air leakage rating (AL): Measures how much air passes through the window assembly. Lower is better.

Ask for the specific NFRC ratings for the windows being proposed, not just “ENERGY STAR certified.”

For a full breakdown: Questions to Ask a Window and Door Contractor About Energy Performance

What is the frame material, and what are the trade-offs?

Window frames come in several materials, each with different performance, maintenance, and cost profiles:

Vinyl (PVC): The most common residential option. Low maintenance, good thermal performance, affordable. Quality varies significantly — thicker walls and multi-chamber profiles perform better.

Fibreglass: Superior thermal performance, dimensional stability (doesn’t expand and contract as much as vinyl in temperature swings), longer lifespan, paintable. Premium price.

Wood: Traditional aesthetic, good insulation, but requires ongoing maintenance (painting or staining). Often used in heritage homes or high-end applications.

Aluminum: Strong, durable, low maintenance, but poor thermal performance unless thermally broken. Common in commercial applications; less ideal for residential in cold climates.

Ask specifically what frame material is being proposed and why it’s appropriate for your situation.

What glass package is included?

Modern window glass is far more complex than it appears. Ask about:

  • Number of panes: Double-pane (two lites) is the current standard. Triple-pane offers significantly better performance in cold climates.
  • Low-E coating: A microscopically thin coating that reduces heat transfer. Ask which Low-E coating is being used and what it’s optimized for (solar control vs. insulating).
  • Gas fill: Argon or krypton gas fill between panes improves insulating performance.
  • Spacer type: Warm-edge spacers reduce condensation at the edges of the glass unit.

For more: Questions to Ask a Window and Door Contractor About Products and Materials

Questions About the Installation

Is this a full-frame replacement or an insert replacement?

This is one of the most important questions in window replacement — and one that’s frequently not explained clearly in sales pitches.

Full-frame (or new construction) replacement: The entire window, including the frame and all exterior trim, is removed down to the rough opening. New framing, flashing, and a completely new window unit are installed. More disruptive and expensive, but allows inspection and correction of the rough opening, installation of proper flashing, and a complete seal.

Insert (or pocket) replacement: A new window is installed inside the existing frame, which stays in place. Less disruptive and less expensive — but doesn’t allow inspection of the rough opening, doesn’t address any rot or damage in the existing frame, and can reduce the glass area if the existing frame is deep.

Ask which approach is being proposed and why. For windows showing signs of rot, water damage, or failed flashing, a full-frame replacement is almost always the right approach.

What a good answer looks like: A clear explanation of which approach is being proposed, with a rationale tied to the condition of your existing windows and frames.

How will the windows be flashed and sealed?

Flashing is the moisture management detail that prevents water from infiltrating at the window-to-wall interface. It’s the most consequential installation detail — and the one most commonly skipped on lower-quality installations. Ask specifically how each window will be flashed and what materials will be used.

What a good answer looks like: Self-adhering flashing tape at the sill and jambs, integrated with the house wrap, before the window is set and trimmed.

For more: Questions to Ask a Window and Door Contractor About Installation

Questions About Warranties

What manufacturer warranty comes with these windows?

Quality windows carry substantial manufacturer warranties — often 20 years or lifetime on the frame and hardware, and 10–20 years on the insulating glass unit (seal failure). Ask what the specific warranty terms are and what conditions must be met to maintain coverage.

What installation warranty do you offer?

Separate from the product warranty, the installer should offer a written warranty on their workmanship — covering the installation quality, the flashing, and the caulking and sealing. Ask for it in writing.

For a full breakdown: Questions to Ask a Window and Door Contractor About Warranties

Red Flags to Watch For

Door-to-door sales with same-day pressure. Window companies that cold-call and pressure for a same-day decision are using sales tactics designed to prevent comparison shopping. No window replacement requires a same-day signature.

Vague product specifications. Any quote that doesn’t name a specific product with NFRC ratings is hiding the quality of what’s being installed.

“Free installation” or extremely low prices. These almost always mean inferior product or hidden costs elsewhere — a lower-quality glass package, substandard installation, or a warranty that’s worth nothing.

Full replacement recommended for condensation between panes. Failed IGU seals can often be addressed by replacing the glass unit alone — not the entire window.

For a full guide: Red Flags When Hiring a Window and Door Contractor

Before They Start: A Quick Checklist

  • Business registration and tax-registration number verified
  • Manufacturer installation certification confirmed
  • Certificate of insurance and workers’ compensation coverage clearance received
  • Written quote with specific product name, NFRC ratings, and frame material
  • Full-frame vs. insert approach confirmed and understood
  • Flashing method discussed and agreed
  • Warranty terms — manufacturer and workmanship — in writing
  • Payment schedule confirmed

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