The window industry has more product complexity than most homeowners realize — and more opportunity for a contractor to sell down in quality while keeping the price high. Understanding the key product specifications, what they mean, and how to compare them across quotes is what separates an informed buyer from one who pays for a premium and receives a standard product.

“Most homeowners ask about the warranty duration. The questions they should be asking are about the frame wall thickness, the glass package, the spacer type, and whether the Low-E coating is appropriate for their climate zone. Those details determine how the window actually performs. The warranty duration tells you how long the company hopes it lasts — the specs tell you whether it will.”

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

Frame Material Questions

a living room filled with furniture and windows

What frame material are you recommending, and why?

Frame material is one of the most significant product decisions in window replacement. Each has meaningful trade-offs:

Vinyl (PVC): The dominant residential choice. Low maintenance, good thermal performance, and affordable. However, vinyl quality varies enormously. Key indicators of quality vinyl:
– Frame wall thickness: thicker walls are more rigid and durable
– Number of internal chambers: more chambers = better thermal break
– Fusion-welded corners vs. mechanically fastened: welded corners are stronger and more airtight
– UV stabilizers: cheaper vinyl fades and becomes brittle faster

Ask specifically about wall thickness and chamber configuration if vinyl is being proposed.

Fibreglass: Significantly stronger and more dimensionally stable than vinyl — fibreglass expands and contracts at nearly the same rate as glass, so the seal between frame and glass is less stressed over time. Paintable, longer-lasting, and superior thermal performance. Typically 15–20% more expensive than comparable vinyl.

Wood: Traditional look, excellent insulator, paintable and stainable. Requires ongoing maintenance (painting or staining every 5–10 years) to prevent rot. Some products use wood interiors with aluminum or vinyl exteriors for reduced maintenance.

Aluminum: Strong, low maintenance, slim sightlines. Poor thermal performance unless the frame has a proper thermal break separating the interior and exterior aluminum sections. Generally not recommended for primary windows in cold Canadian climates without thermal breaks.

What a good answer looks like: A specific frame material recommendation with a clear rationale tied to performance, maintenance tolerance, budget, and the specific climate of your home.

Glass Package Questions

Wooden chair in a room with plants and plants

How many panes does the glass unit have?

Double-pane (IGU): Two lites of glass with a sealed air or gas-filled space between them. The current standard. Significantly better than single-pane.

Triple-pane: Three lites with two sealed spaces. Measurably better thermal performance — particularly relevant in cold Canadian climates. Heavier and more expensive than double-pane, but the performance difference in many regions winters is significant.

For any home where energy performance is a priority, ask whether triple-pane is available and what the cost difference is.

What Low-E coating is being used?

Low-E (low-emissivity) coatings are microscopically thin metallic layers applied to one or more surfaces of the glass that dramatically reduce radiant heat transfer. In your country, the appropriate Low-E coating depends on the application:

Soft-coat (sputtered) Low-E: Applied to the interior surface of the glass unit (surface 3 in a double-pane unit). Provides excellent insulating performance. More common in higher-performance windows.

Hard-coat (pyrolytic) Low-E: Applied during glass manufacturing. More durable but somewhat lower performance than soft-coat.

The coating’s position within the glass unit (which surface it’s on) affects whether it primarily blocks heat from leaving your home (better for Canadian winters) or blocks solar heat gain (better for summer cooling). Ask the contractor which coating is being used and what it’s optimized for.

What gas fill is between the panes?

Air: The baseline. Less thermally effective than gas fills.

Argon: The most common gas fill — significantly better insulating performance than air, with minimal cost premium. Should be standard in any quality window.

Krypton: Better than argon, but more expensive. Often used in triple-pane units where the narrower gas space makes krypton’s properties more advantageous.

Ask whether argon or krypton fill is included. Any quality window should have argon at minimum.

What type of spacer is used between the panes?

The spacer is the edge seal that separates the two panes of glass and maintains the gas fill. Traditional aluminum spacers create a thermal bridge at the edge of the glass — the area most prone to condensation.

Warm-edge spacers (foam, silicone, or composite materials) have significantly lower thermal conductivity than aluminum, reducing edge condensation and improving overall window performance.

Ask whether warm-edge spacers are included. They should be standard in any quality product.

Door-Specific Questions

What is the door’s insulation core?

Entry doors should have an insulated core — polyurethane foam is the most effective insulator. Ask about the core material and the door’s R-value (thermal resistance). A quality insulated entry door should have an R-value of at least R-10 to R-15.

What is the door material?

Steel: Durable, secure, good insulation when properly constructed, relatively low maintenance. Can dent. Prone to condensation in very cold weather if improperly insulated at the frame.

Fibreglass: Excellent durability, won’t dent or rust, good insulation, can be textured to look like wood. Premium option.

Wood: Beautiful but requires significant maintenance and is more susceptible to warping in Canadian climate swings.

Is the door pre-hung or slab only?

A pre-hung door comes with the frame and hinges already assembled — the entire assembly is installed in the rough opening. A slab door is just the door panel, which is hung in an existing frame. Ask which is being proposed and ensure the frame and weatherstripping are included if it’s a full replacement.

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