Understand every layer of the window.
Our window reference, from the first symptom to the finest detail. Explore glass, frames, comfort, installation, restoration and the life of the building—with deep guides and tools that help you ask better questions.
A window joins several systems: glass, sash, frame, hardware, seals, the wall and the room around it. Good decisions start by identifying the problem and comparing the complete assembly, installation and exposure. This reference connects the practical decisions with the science behind them, using Canadian planning context and clearly identified international technical sources.
A window is a whole system. Explore every layer.
Start with your question, then follow the detail from glass and frames to the wall, the room and the life of the building. Canadian planning context; international technologies explained with their limits.
Plan, buy & specify
Record the openings, define the scope, compare evidence and keep a useful project record.
8 topics · Explore →02 / Field of studyHeat, sun & daylight
Understand what ratings measure, what light does and how comfort changes at the glass.
6 topics · Explore →03 / Field of studyGlass & glazing technology
Coatings, cavities, edge seals, safety glass, sound and emerging glazing systems.
14 topics · Explore →04 / Field of studyWindow & facade systems
Opening styles, roof daylight, complex assemblies, commercial facades and accessible operation.
7 topics · Explore →05 / Field of studyThe window in the wall
Replacement methods, flashing, air seals, verification, interfaces and handover.
7 topics · Explore →06 / Field of studyRepair, restoration & ownership
Locate the failed component, explore conservation and plan maintenance through the life of the window.
8 topics · Explore →07 / Field of studyClimate, safety & approvals
Exposure, Canadian requirements, heritage and condominium decisions, with jurisdictions identified.
8 topics · Explore →08 / Field of studyTools & reference
Workbooks, calculators, the glossary, questions and source-backed planning aids.
7 topics · Explore →I own a home
Understand the problem before choosing a product.
I am planning a renovation
Connect the window decision to the wall and project.
I want the technical detail
Read ratings, physics and system limitations together.
Build a window, then leave it out on a minus-thirty night
Pick the frame, double or triple glazing, low-e, gas fill and spacer, set the coldest hour and your room humidity, and watch the glass temperatures, heat flow and fog line respond. Play the night to see supper and morning showers push the dew point up.
What the model shows, in words
Three parts, three temperatures
A window is not one surface. The middle of the glass, the bottom edge where the spacer bridges the panes, and the frame each settle at their own temperature on a cold night. The model reports all three from the room side, using the temperature-factor idea behind CSA condensation testing, where zero means as cold as outdoors and one hundred means as warm as the room.
Why fog starts at the bottom
Air chilled against the pane slides down and pools, and the spacer conducts cold into the last few centimetres of glass. That makes the lower edge the first place to reach the room's dew point. Swap an aluminum spacer for a warm-edge one and watch the fog line drop, which is the reason the glass package guide treats the spacer as more than a detail.
What each upgrade buys
Low-e and argon warm the centre of the glass the most; a third pane warms it further and lifts the edge along with it. The frame choice matters most at the corners, where a thermally broken aluminum frame stays noticeably colder than vinyl, fibreglass or clad wood. The values behind these changes are typical textbook figures, not ratings for any product you can buy.
Humidity moves the line as much as glass does
The dew point comes from the room, not the window. Push the humidity slider up and even a well-built unit starts to sweat at the edge on the coldest hour. The panel shows the highest humidity your build can hold before fog appears, an illustration of how a condensation threshold changes; it is not a healthy indoor humidity recommendation; window condensation covers the other household fixes.
Use it to ask better questions
The model is illustrative, so treat it as a way to understand trade-offs, not to pick a product. When quotes arrive, ask for the certified whole-window U-factor and Energy Rating, the spacer type and any condensation-resistance figure for each window, then compare them side by side with the Window Quote Checker.
See how the glass layers fit together
The panes, gas spaces, low-e coatings and edge spacer work together. Compare the certified rating of the complete window when choosing a product. Explore the glass package →
Where are you in your window project?
Pick the closest match. Each path goes to the guide that answers it in full.
Window Budget Planner
Enter up to six groups of windows with a count and your own low and high unit prices in Canadian dollars. Add a project allowance and your chosen contingency and tax percentages. The planner totals those inputs and identifies unpriced rows. Frame, glazing, installation and cladding notes describe your scenario; they do not trigger automatic price multipliers.
How the Window Budget Planner works →
Also freeWindow Quote Checker
Window Quote Checker: compare up to three window replacement quotes on price per window, warranties and ten inclusions, with questions to ask each one.
Also freeWindow Rating Lab
Compare whole-window heat transfer, convert SI and imperial U-factors, and calculate illustrative heat flow while keeping rating scope and assumptions clear.
Also freeWindow Moisture Lab
Explore window dew point, measured surface temperature and condensation margin with an educational moisture lab, clear liquid-water formula and frost limitations.
Also freeWindow Project Workbook
Build a homeowner window inventory with room, approximate size, operation, condition, orientation and priorities; print, copy or export it as a briefing worksheet.
Window Budget Planner
Read these first
The opening inventory
Give each window an identity, record its observed condition and keep approximate planning measurements separate from order dimensions.
CornerstoneWindow ratings in context
Convert SI and US U-factor units and explore fixed-condition heat flow without turning it into an annual savings promise.
CornerstoneA complete specification
Join the exact product, configuration, installation interfaces, evidence and acceptance criteria in one comparable schedule.
CornerstoneRepair and restoration
Understand the original assembly and failed component before choosing a conservation or replacement approach.
What it looks like
Illustrations of what this work involves and what a camera or a trained eye picks up. Every guide on ReplaceWindows.ca carries more like these.
01 /Begin with a question, not a product category
Windows are experienced from the room: a cold seat beside the glass, a handle that no longer works smoothly, an afternoon glare problem, fog that will not wipe away, water below the sill. Those observations are useful, but they do not all point to the same remedy. Start by recording which opening is involved, which surface is affected, the weather and the time of day. A photograph with an opening identifier is much more useful than a general statement that the house needs better windows.
The component failure guide separates room-side condensation, cavity moisture, operation problems and water paths at the wall. The repair-or-replace guide then explores what an assessment may find. A failed glass unit can be a different problem from a damaged frame or concealed wet wall. A new window is one possible intervention; it should follow evidence about the assembly and the opening.
Create a record in the opening workbook before comparing suppliers. Approximate measurements help describe a project, while manufacturing and ordering dimensions belong to a verified measurement process. Mark bedrooms, difficult access, unusual shapes and visible wall damage as questions for the appropriate professional. This helps a quotation describe the actual work rather than merely a number of units.
02 /Read the whole assembly, and then its individual layers
The pane count is easy to see in a sales description. The coating, spacer, edge seals, frame details and rated configuration require more careful reading. A centre-of-glass number excludes parts of the assembly that influence whole-window performance. Compare figures with the same units, scope, product configuration and rating method. A well-written specification identifies the window series and the intended glass package rather than relying on a broad phrase such as premium triple glazing.
Use the rating lab to connect U-factor with area and a fixed temperature difference. Use the solar and daylight guide to separate heat admitted from visible light transmitted. These questions interact: a room can benefit from winter sun and still overheat in another season. Orientation, exterior shading, glazing area and the use of the room all belong in the decision.
The material guides explain frames; the glazing guides go further into low-e surfaces, edge seals and gas cavities, safety glazing and acoustic ratings. A characteristic that improves one measure does not establish performance in every other category. The evidence should match the problem you are trying to solve.
03 /Treat the window and the wall as one project
A window product arrives with a manufactured frame. The building provides the opening, structural support, water-management layers, insulation and air-control connections. The project succeeds when those systems meet coherently. An insert installation and a full-frame installation expose different parts of the existing construction. Choose the intervention after an assessment of the existing frame, drainage, damage and surrounding finishes.
Read installation, flashing and sealing with the insert versus full-frame guide. The diagrams explain principles. The actual detail must follow the product instructions, the wall construction, the design and applicable requirements. A generic drawing cannot establish every fastening, sealant or flashing detail for masonry, stucco, drained cladding and an existing concealed opening.
Plan the evidence before it disappears behind trim. The acceptance and punch-list guide separates concealed interface records from visible finish and operation checks. Agreed checkpoints, photographs and written open items make the handover clearer. They also help distinguish an installation question from a product defect when a problem appears later.
04 /Explore beyond the standard replacement window
Historic wood sashes, storm windows, tilt-and-turn hardware, grouped bays, roof daylight systems and commercial facades each have their own logic. A conservation decision includes historic fabric and repairability. A skylight meets a roof rather than an ordinary wall. A large mulled assembly needs a designed connection and load path. A facade system must be considered with movement, drainage and its interfaces to the building structure.
The library includes historic restoration, secondary glazing, roof windows and skylights, and curtain wall, storefront and window wall. These are separate systems, so the comparison begins with their application and limitations rather than assuming one is a larger version of another.
International technologies are included where they illuminate a useful question. Vacuum, aerogel and dynamic glazing are explained through their mechanisms and evidence limits. Passive House specification considers the installed assembly and junction. These guides distinguish technical understanding from a claim of local availability, Canadian approval or suitability for an individual building.
05 /Make cost and approval decisions traceable
There is no single national window price that captures every product configuration, wall, access condition and installation scope. The budget planner uses numbers from your own written quotes. It multiplies your unit amounts by counts and applies only the allowances, contingency and tax percentage you enter. Blank prices remain unpriced. Frame and glass descriptions help compare scope; they do not secretly apply a material premium.
The quote checker highlights stated inclusions and unanswered questions. A low average per opening is not enough to compare a fixed picture window, a complex bay and a new opening with structural work. The specification schedule helps keep the product and installation requirements consistent, while project change records make an altered scope and its effects visible.
Rules and financial programs require the same care. Check the actual jurisdiction, adopted code, property status and program eligibility before committing. Permits and egress, condominium planning and heritage planning identify different approval questions. A standard publication date is distinct from the edition referenced by a regulation or certification program. A source link provides a place to confirm the requirement.
06 /Keep learning after installation
Ownership begins with product identity, installation records, care instructions and the terms of the written warranties. Keep the schedule and acceptance record with the building documents. Track the season and location of symptoms, the maintenance performed and the response to a reported concern. These records make a future assessment more useful than a recollection that the window has always leaked.
Explore hardware and weatherstripping, maintenance and lifecycle, and warranty claim evidence. Interior changes matter too: furniture, window coverings and room ventilation can alter conditions at the glass. The moisture lab compares measured conditions with an approximate liquid-water dew point; it does not prescribe a healthy humidity target or diagnose a leak.
ReplaceWindows.ca is the HAUSE window reference and an independent information and service-request site. We do not manufacture or install windows. Every guide is a starting point for a clearer decision, and carries sources to follow into the technical detail. Use the glossary when a label introduces an unfamiliar term. If you want to discuss a project, the separate request form explains the consent to contact you before you send it.
Start exploring the window reference
Choose noise-control windows for the sound you actually hear
Compare STC, OITC and frequency-band data for window noise control. Understand glazing, seals, flanking paths and the limits of laboratory acoustic ratings.
Building ScienceMore glass is not the same as better daylight
Plan replacement-window daylight, view, clear aperture, mullions, glare, colour, privacy and shading, with a practical room brief and limits of daylight metrics.
Building ScienceSpecify the installed opening, not a Passive House adjective
Specify high-performance windows using climate, verified component data and installation junctions. Distinguish Passive House programmes and building assessment.
Building ScienceSunlight, daylight and heat: SHGC and visible transmittance explained
A detailed window selection guide to SHGC, visible transmittance, g-value, light-to-solar gain, tint and orientation, with clearly labelled numerical examples.
Building ScienceFollow the sun before choosing the glass
Choose window solar gain and exterior shading by orientation, season and room use. Evaluate low-angle sun, overheating, overhang geometry and practical limits.
Building ScienceClose tightly, ventilate deliberately
Plan replacement windows alongside ventilation and airtightness. Understand leakage, fresh-air systems, moisture, smoke, overheating and enclosure connections.
Care and repairA window symptom is a starting point, not a diagnosis
A careful observation guide to surface condensation, insulating-glass fogging, cracked glass, distorted reflections, frame leaks, drainage and hardware failures.
Care and repairThe moving parts: hardware, weatherstripping and screens
Identify operators, balances, hinges, locks, rollers, gaskets and screens; diagnose operation problems, order compatible parts and protect window drainage.
Care and repairOwn the window for its whole life
Build a window maintenance record: inspect glass, drainage, seals, hardware and finishes, plan repairs, and document product details and responsible disposal.
Window replacement in Alberta: climate, hail, permits, CEIP and costs
Window replacement in Alberta: Calgary, Edmonton, Red Deer and Lethbridge climate, hail, permit rules, the door-to-door sales ban, CEIP and planning costs.
Glass & RatingsMake the barrier visible from the bird’s approach
Plan bird-visible window patterns with exterior coverage, spacing and contrast. Compare research, installation choices and the limits of collision-test ratings.
ENERGY STAR window ratings explained: U-factor, ER, SHGC and VT
ENERGY STAR window ratings in Canada explained: U-factor, Energy Rating, SHGC, VT, air leakage, the old climate zones and how to read a label.
Frequently asked
How does the window budget planner set a price?
It uses your own lower and upper unit quote inputs, counts and entered project allowances. Blank prices remain unpriced. It adds no national market prices or material multipliers.
Are triple pane windows worth it?
Often in colder regions and on north- and east-facing walls, for large glass and in homes with condensation. In mild coastal climates, good double glazing may be enough. Compare certified whole-window ratings.
Do ENERGY STAR climate zones still apply?
No. Since January 1, 2020, ENERGY STAR Canada uses one national requirement for windows and doors. Zones appear on older labels.
What is the difference between insert and full-frame replacement?
An insert fits a new window inside the old frame; full-frame removes everything to the rough opening so framing, flashing and insulation can be redone. Full-frame costs more and fixes more.
Do I need a permit to replace windows?
Usually not for same-size replacement in a house, but rules are local. Enlarging or adding windows needs a permit, and some cities also list changes to a window's type or operation. Ask your municipality.
Does ReplaceWindows.ca install windows?
No. 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.
Describe the problem once. Get a straight answer.
Tell us what you are seeing — when it happens, where, the age of the house and anything you have already been told or quoted. The HAUSE Home desk replies with next steps and, where available, a local contractor for the job.
Keep people and pets clear of damaged glass and the opening. Arrange professional make-safe service for loose glass or an unsecured window.