Craft
Choosing Windows and Glazing That Survive a Burnaby Winter
Frame material, glazing package, low-E coating, install detail. Four decisions that determine whether your windows are still tight twenty years from now or fogging in their first wet season.
In a wet, mild, cloud-covered climate like Burnaby's, windows are working all year. They're holding heat in November, rejecting solar gain in July, surviving 200 days of horizontal rain, and — more than any other component — driving how a home feels to live in. They're also the single most error-prone building product in residential construction. Get the window right, and the home performs for thirty years. Get it wrong, and you're chasing condensation and moisture damage from year three.
This post is for the homeowner picking windows for a custom home in Burnaby, Vancouver, or anywhere on the BC south coast — the questions to ask, the trade-offs to understand, and the install details that matter more than the brand on the sticker.
Why windows matter most on the west coast
The BC south coast climate is mild, but it's relentlessly wet. The wind-driven rain test that windows used to fail in this region was developed because of how Vancouver and Burnaby weather actually behave: not extreme on any one variable, but unforgiving in combination. A window that performs in Calgary's dry cold can leak miserably in Burnaby's wet winter.
Windows also drive a disproportionate share of a home's energy performance. In a Step 5 envelope, with R-30+ walls and R-60 ceilings, the windows are typically a tenth of the surface area but a third of the heat loss. Improving from a mid-tier window to a high-tier window has more energy impact than a dozen other decisions.
The BC Energy Step Code doesn't prescribe specific windows, but the performance modelling at Step 5 effectively rules out vinyl-frame double-pane assemblies for most custom homes. Triple pane and high-performance frames become the practical baseline.
Frame materials compared
Four frame materials cover almost every Burnaby custom home we build:
- Fiberglass. Dimensionally stable, durable, paintable. Fiberglass moves with temperature roughly the same as the glass it surrounds — meaning the seal between frame and glass stays intact through thermal cycling. The current preference for high-performance custom homes on the BC south coast.
- Aluminum-clad wood. Wood interior, aluminum exterior. Beautiful inside, weatherproof outside. Higher cost than fiberglass but unmatched aesthetic. Common in higher-end Vancouver and West Vancouver builds.
- Thermally broken aluminum. All-aluminum frame with a thermal break (insulating bridge) between interior and exterior portions. Used for very large openings — patio doors, lift-and-slide systems — where the structural span demands metal. Lower thermal performance than fiberglass for the same nominal frame profile.
- Vinyl. The most common residential frame in BC. Inexpensive, low-maintenance, and adequate for many applications, but with two real limitations: dimensional movement with temperature (cycling stresses the seal between glass and frame over time) and limited large-opening structural capacity. We use vinyl in some applications. We don't use it for everything.
The frame material decision is largely about durability and aesthetic. The energy performance comes mostly from the glazing package.
The glazing package — U, SHGC, VT
Three numbers describe a glazing package, and they are usually printed on the NFRC label on the window when it ships:
- U-factor. How well the window resists heat loss. Lower is better. A high-performance triple-pane unit will be in the U-0.18 to U-0.22 range. Code-minimum will be U-0.30 or higher.
- Solar Heat Gain Coefficient (SHGC). How much solar energy the window admits. Higher is better in winter (free heat); lower is better in summer (less cooling load). On the BC south coast, where summers are mild and winters are gray, an SHGC in the 0.35 to 0.45 range is usually right.
- Visible Transmittance (VT). How much daylight gets through. Higher is better for daylighting; the trade-off is that high-VT, low-SHGC coatings are more expensive.
The combination matters. A low U-factor with a low SHGC produces a tightly insulated, dim window — fine for a north-facing bedroom, wrong for a south-facing kitchen. We work room by room with the energy advisor and the architect to specify glazing per orientation, not as one number for the whole house. Energy Star Most Efficient ratings are a useful filter for the high-performance end of the catalog.
Low-E coatings for the west coast
Low-emissivity (low-E) coatings are microscopic metallic layers on the glass that reflect long-wave heat. They're standard on every modern window. The variable is which low-E.
For the BC south coast, we generally specify a low-E that prioritizes heat retention over solar rejection. Our cooling load is small. Our heating season is long. A coating that traps heat in winter outweighs the modest summer benefit of more aggressive solar rejection. South- and west-facing rooms with summer overheating exposure may justify a different coating — usually we treat them with exterior shading or deep overhangs rather than aggressive low-E.
The biggest mistake we see on west-coast custom homes is applying southern-California glazing logic to a Vancouver climate. We don't have a cooling problem. We have a daylight problem. The right window admits light without losing heat.
— Sanj Aggarwal, CHBA BC Master Residential Builder
Installation detail
The installation detail is where windows quietly fail. The window product can be excellent and the install can ruin it. The details that matter:
- Sill pan. A waterproof tray under the window that drains any water that gets past the seal back to the exterior. Mandatory in best practice; missing in too many homes. We use either a self-adhered membrane or a manufactured sill pan, never a strip of caulking.
- Weather-resistive barrier (WRB) integration. The wall's WRB has to lap correctly with the window flanges — top flange behind, side and bottom in front. Reverse the lap and water gets driven inward.
- Air sealing on the interior side. Backer rod and sealant or a low-expansion foam between the frame and the rough opening, full perimeter. This is the airtight seal that the Step Code blower-door test measures.
- Drainage to the exterior. The space between the frame and the rough opening must drain outward. Stuffing it solid with foam without a drainage path is a slow leak waiting to happen.
- Flashing. Head flashing extends past the side trim, kicks water out, and is taped at the top into the WRB.
We've taken over more than one project where every window was installed without sill pans. Removing and reinstalling them was the only fix. There's no shortcut for getting this right.
Choosing a manufacturer
The right manufacturer for a Burnaby custom home is one with a track record on the BC south coast, accessible technical support when an installer hits a unique condition, and a service network if a unit needs warranty work in year eight. We work regularly with several Canadian and BC-specific manufacturers — among them Cascadia Windows, Innotech Windows + Doors, and Westeck Windows + Doors, all with BC-based manufacturing — and reputable U.S. and European brands depending on the project.
Lead times are real and seasonal. High-performance windows in 2026 are typically running ten to sixteen weeks from order to delivery. We confirm the schedule with the manufacturer at pre-construction so the framing crew isn't standing around a hole in the wall.
How window performance is verified at Step Code compliance
On a Step 5 home in Burnaby, window performance is not self-reported. The certified Energy Advisor runs a blower-door test at the end of construction to verify the whole-envelope airtightness target of 1.0 ACH50. Poor window installation is one of the most common reasons first blower-door tests come back high — the air leaks at the rough-opening perimeter find the tester faster than they find the homeowner.
The energy model submitted at permit specifies assumed U-factors, SHGCs, and window-to-wall ratios for the building. If the window products actually installed differ from what was modelled — and this happens when the architect specifies one product and the contractor substitutes a cheaper alternative — the energy advisor can require a remodel or, in some cases, reject the compliance file.
This is why we lock the window specification before permit, confirm manufacturer lead times at pre-construction, and verify the NFRC labels match the specification when the units land on site. It sounds like project-management overhead. It's actually the thing that prevents an $800,000 envelope from failing compliance on the last day of construction.
A short selection checklist
When you sit down with the architect to specify windows, the questions worth answering for every opening:
- Frame material — what's the right call for this opening?
- Triple pane or double pane — does the energy model require triple here?
- U-factor target — what does the model require?
- SHGC target — does this orientation want gain or rejection?
- Operable or fixed — and if operable, awning, casement, slider, hopper?
- Egress requirement — is this a bedroom or a basement habitable room? (Section 9.9.10 of the BC Building Code defines minimum egress dimensions.)
- Manufacturer and lead time — can the schedule absorb the order?
This is also the moment to look at the doors — patio doors, entry doors, garage doors. They follow most of the same logic. The patio door in particular is often the largest window in the house.
For more on how envelope decisions stack at Step 5, our companion piece on Step Code Step 5 covers the broader thermal envelope. For the durability conversation that windows are part of, why we don't believe in builder-grade and materials that age beautifully cover what survives a wet coast and what doesn't.
If you're at the moment where window selection is on the table for a Burnaby, Vancouver, or North Vancouver custom home, reach out. We'll walk through the schedule, the manufacturer options, and what the install detail needs to look like for your specific climate exposure.
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