Plan your window replacement before the first quote.

01 /Start with what is actually failing

Before choosing new windows, work out what is wrong with the old ones, because many problems are repairs rather than replacements. Fog between the panes means a failed glass seal, and a new sealed unit in the existing sash often fixes it. A crank that spins or a sash that will not stay up is worn hardware. A draught at the trim is usually a gap between the frame and the wall that was never sealed. None of these, on its own, means the whole window has to go.

Replacement makes sense when the frame itself has failed or the window is holding the house back: rot or softness at the sill, water stains below the window, a frame out of square, single glazing or sashless sliders, several failing parts at once, or a bedroom window too small to escape through. The repair or replace guide goes part by part, and is window replacement worth it weighs energy, comfort, condensation and resale.

02 /Four choices set most of the price and performance

Once you know which openings need new windows, four choices decide most of the cost and how the windows perform. Window type sets ventilation, airtightness and egress: casements and awnings seal tightly, sliders and hung windows cost less, fixed windows are tightest of all. Frame material sets upkeep, stiffness and look: vinyl is the value baseline, fibreglass is stiffer and paintable, clad wood gives a wood interior. Glass sets heat loss and condensation: double or triple panes, low-e coatings, gas fill and warm-edge spacers. Installation method sets what gets fixed: an insert keeps the old frame, full-frame goes back to the rough opening.

Each choice has its own guide: window types, vinyl windows, fibreglass vs vinyl, low-e glass, gas fill and spacers and insert vs full-frame. The cost guide shows whole-house examples, and how to choose replacement windows pulls every choice into one specification.

03 /Ratings and climate: what changed, and what still matters

Window energy performance in Canada is certified under NRCan's ENERGY STAR program. The current specification, version 5.0, in effect since January 1, 2020, has one national requirement: a U-factor of 1.22 W/m²·K or lower, or an Energy Rating of 34 or higher, for windows and doors, plus low air leakage. The three climate zones many people still ask about belonged to the previous version and survive mainly on older labels and in sales material.

Climate still shapes good choices. Colder places reward lower U-factors and triple glazing, especially on north and east walls. South-facing glass can collect useful winter sun with the right coating, while west-facing glass may need a lower solar heat gain coefficient to avoid overheating. Windy, wet coasts need windows rated for wind-driven rain. The climate zones page explains heating degree-days and lists how major Canadian cities were zoned, and ENERGY STAR window ratings explained decodes every number on a label.

04 /A five-step plan for replacing windows

1. List every opening

   Note each window's type, rough size, room and wall cladding, and mark bedrooms, because their windows must still work as emergency exits.

2. Decide repair or replace per window

   Fix glass units, hardware and trim sealing where frames are sound; replace where frames, flashing or glazing have failed.

3. Choose frame, glass and method

   Match glass to each elevation and climate, and choose full-frame wherever there is any sign of water damage.

4. Run the planner

   Get a planning range for your mix of windows and see how each choice moves it before anyone quotes.

5. Collect and compare quotes

   Ask for the product series, glass package, method and inclusions in writing, then line the offers up in the Window Quote Checker.

05 /Installation is half the window

A certified window can still leak, draught or fog along its edges if it is installed badly. A good installation manages water with a sloped sill pan and shingle-lapped flashing, stops air with a continuous interior seal, insulates the gap with low-expansion foam or backer rod and sealant, and supports the frame with shims so it stays square. Exterior caulking is the last line of defence, not the first. Brick and stucco walls change the details, and bedroom windows must still meet egress rules after replacement.

Read installation, flashing and sealing, brick and stucco window replacement and permits and egress before you sign. Then make sure each quote names the product series, glass package, method and inclusions, using the quotes and warranties guide and the Window Quote Checker. Check for programs in your province with the rebates, tax and insurance guide, and pick your timing with the best time to replace windows. How to choose a window replacement company lists the checks worth making on any installer, and DIY window replacement explains when doing it yourself is realistic.

ReplaceWindows.ca is part of HAUSE Home, an independent information and service-request network. It does not make, sell or install windows and does not rank brands. Unfamiliar terms are defined in the glossary, and short answers to common questions are in the FAQ. When you are ready, you can request quotes and attach your planner summary.

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