What's actually different about a new-construction window versus a replacement window?

New-construction windows have a nailing fin that ties directly into the wall's housewrap and flashing before siding goes on, while replacement windows are sized to fit into an existing frame without disturbing the exterior finish. New builds, additions, and full tear-offs use the nail-fin style because the wall is open and can be flashed as one continuous system. Trying to use the wrong type for the situation usually creates water management problems down the line.

What should I ask a contractor before hiring them to install windows on a new build in Aldergrove?

Ask to see their actual flashing sequence — sill pan, tape order, and how they handle the nailing fin — since that detail matters more than the brand of window they sell. Ask whether they've worked cross-border jobs before and understand BC permit and certification requirements. Also ask how they coordinate with the general contractor's framing schedule, since window timing on a new build is tighter than on a retrofit.

Do you install a specific window brand for new construction?

We don't lock every job into one brand. What we insist on is that the product is properly certified for where it's going in — NAFS/AAMA for U.S. builds, CSA A440 listing where BC code requires it — and rated for the exposure that specific wall will see. The right choice depends on the build, the budget, and how exposed the elevation is to wind and rain.

What is a nailing fin and why does it matter so much for a tight seal?

The nailing fin is the flange around the perimeter of a new-construction window that gets fastened through the sheathing into the framing, and it's the surface that the housewrap and flashing tape overlap onto in shingle-lap order. If it's not integrated correctly with the water-resistive barrier, water can get behind the fin and into the wall cavity with no way to drain back out. Getting this one detail right is the difference between a window that stays dry for decades and one that causes hidden rot.

Does a window install in Aldergrove, BC need to meet different requirements than one in Lynden, WA?

Yes — BC follows its own building and energy code, and window certification on the Canadian side typically looks for CSA A440 listing rather than the NAFS/AAMA testing common in the U.S. market. Energy performance requirements have also trended higher on the BC side in recent code cycles. We check these requirements as part of planning any Aldergrove project so the windows we install match what the local permit process expects.

New-Construction Windows for Aldergrove, BC Homes

New-Construction Windows: What They Are and Why Sequence Matters

New-construction windows are built with a nailing fin around the perimeter of the frame, designed to be installed into a bare rough opening before housewrap, flashing, and siding go on. That's different from a replacement or "pocket" window, which is sized to slide into an existing frame after the exterior finish is already in place. On a new build, an addition, or a full tear-off where the walls are open to the studs, the nail-fin window is the correct product — it lets us tie the window directly into the wall's water-resistive barrier as one continuous system, rather than working around finished siding.

That sequencing is the whole point. A window is not waterproof on its own. It's one piece of a layered system that includes the sheathing, the housewrap or building paper, the flashing tape, the sill pan, and the siding itself. If any one of those layers is installed out of order or skipped, water finds the gap eventually — sometimes in the first hard rain, sometimes three winters later when the sealant starts to give up. On new construction we get one real shot at getting that sequence right before the wall closes up, which is why we treat the rough opening prep as seriously as the window itself.

What Aldergrove's Climate Asks of a New Window Install

Aldergrove sits just across the line from Whatcom County, close enough to Lynden that we cross the Aldergrove–Lynden border crossing regularly for jobs on both sides. The climate on both sides of that line is the same Fraser Valley and Puget Sound lowland pattern: damp, mild, and wet for a long stretch of the year, with three specific stressors that matter for a window going into a new wall.

Salt Air and Metal Corrosion

The marine-influenced air that moves through this region carries enough salt to matter over years, not days. It's slow going, but it accelerates corrosion on unprotected fasteners, hinges, and cheap hardware finishes. On a new build we're not just picking a window for its looks — we're specifying fasteners and hardware rated for coastal exposure, because a corroded hinge or a rusted fastener at the nailing fin is a much bigger problem to fix after the siding is on than it is to get right at rough-in.

Driving, Wind-Driven Rain

Rain here doesn't fall straight down very often. Wind pushes it sideways into wall assemblies, which means a window's weakest points — the head, the jambs, and especially the sill — take on water under pressure, not just gravity. A flashing detail that would hold up fine in a calm climate can fail here if it wasn't built to shed wind-driven water.

A Long Moss Season

Moss and algae thrive anywhere moisture sits without drying out, and this region gives them months to work with. Around windows, that shows up as green staining on sills and trim, and — more importantly — as a sign that water is sitting somewhere it shouldn't be. A correctly sloped sill and a clean drip line off the window head keep water moving instead of pooling, which keeps moss from getting a foothold in the first place.

Climate Stress	What It Does Over Time	What a Correct Install Does About It
Salt-laden air	Corrodes exposed fasteners, hinges, and unprotected metal trim	Corrosion-resistant fastener specs and hardware suited to coastal exposure
Wind-driven rain	Forces water sideways and upward into gaps at the head and jambs	Shingle-lapped flashing tape and a sealed-but-drainable fin detail
Long moss season	Standing moisture on sills and trim invites moss, algae, and rot	Sloped sill pans and drip details that keep water moving off the wall

Getting the Water Management Right

Most window failures we get called out to fix aren't a bad window — they're a bad flashing job around a perfectly good window. On a new-construction install, the sequence we follow at every rough opening looks like this:

Rough opening checked for square, level, and correct size before the window ever shows up on site
Sill pan flashing installed with end dams, so any water that gets past the window sheds out and away from the framing, not down into the wall
Self-adhered flashing tape applied in shingle-lap order — sill first, then jambs, then head — so every layer sheds onto the one below it
Window set into the opening, shimmed square and plumb without bowing the frame, then fastened through the nailing fin per the manufacturer's spec
Housewrap integrated over the fin at the jambs and head, continuing the shingle-lap principle out to the rest of the wall
Sealant used at the fin to manage air and water where specified — not packed into the rough opening gap, which can trap moisture instead of letting it drain
Interior air sealing handled as a separate step from exterior water sealing, since the two do different jobs

One detail that's easy to get wrong and expensive to fix later: over-sealing. It's tempting to think more caulk equals more waterproof, but sealing the drainage plane shut instead of letting it work as designed just traps whatever moisture does get in. A correct install lets water that gets past the first line of defense keep moving and drain back out — it doesn't rely on one perfect bead of sealant to do all the work forever.

Choosing Materials That Hold Up in This Climate

For new construction, the material decision is easier than on a replacement job because we're not constrained by an existing frame — but it still matters which way you go, especially given the salt air and long wet season.

Material	Moisture / Salt-Air Resistance	Maintenance	Typical Lifespan
Vinyl	Good — won't corrode or rot, seams are the main weak point	Low	20-30 years
Fiberglass	Very good — dimensionally stable, resists moisture well	Low	30-40 years
Aluminum-clad wood	Good exterior protection, interior wood needs the cladding to stay intact	Moderate	25-35 years with cladding intact
Aluminum (thermally broken)	Durable frame, but bare aluminum hardware needs coastal-rated finishes	Low to moderate	25-35 years

We don't push one brand or material on every job. What we do insist on is that whatever goes in is rated for the exposure it's actually going to see — a window facing prevailing wind and rain on an exposed elevation deserves a better weatherstripping and glazing spec than one tucked under a deep eave on a sheltered wall. That's a conversation we have on-site, not a one-size answer.

Cross-Border Realities for a Build in Aldergrove, BC

Working a job in Aldergrove as a Washington-based crew means planning around a few things a purely local BC contractor or a purely U.S. contractor might not think twice about. Building codes differ on each side of the line — BC follows the BC Building Code and its own energy requirements, which in recent years have pushed toward higher-performance windows than a comparable Washington build might require. Product certification is another point worth checking: windows sold and labeled for the U.S. market are typically tested to NAFS/AAMA standards, while the Canadian market looks for CSA A440 listing. On a new build in BC, that's not a detail to skip — it can matter for permit sign-off and for the homeowner's own energy code compliance.

There's also the practical side: coordinating a materials and tool crossing at the Aldergrove–Lynden border crossing, timing deliveries so a truckload of windows isn't sitting in customs on the day framing needs to close in, and working alongside the general contractor's schedule on both sides of a project that may involve trades and suppliers from both countries. None of this is complicated once you've done it a handful of times — but it's exactly the kind of thing that turns into a scheduling headache for a crew doing its first cross-border job.

Our Process, From Rough Opening to Final Seal

Plan review and rough opening verification. We confirm window sizes and rough opening dimensions against the build plans before ordering, catching framing discrepancies while they're still cheap to fix.
Product selection. We walk through material, glazing, and hardware options based on the wall's actual sun and weather exposure, and confirm certification requirements for the BC side of the project where applicable.
Ordering and scheduling. We build lead times and cross-border logistics into the schedule up front so window delivery lines up with when the wall is actually ready, not before or after.
Install day. Sill pan, flashing tape, window set, fastening, and housewrap integration happen in sequence, with each layer inspected before the next goes on.
Final check. We test operation, confirm the seal at the interior and exterior, and walk the job with the builder or homeowner before we call it done.

Where New-Construction Installs Go Wrong

Most of the callbacks we see on new-construction window work trace back to a handful of repeat mistakes, usually made by crews trying to move fast on a tight framing schedule:

Skipping or shortcutting the sill pan because "the flashing tape will handle it"
Fastening through the nailing fin without shimming, which can bow the frame and cause the sash to bind or leak at the corners
Sealing the rough opening gap solid with foam or caulk instead of leaving the drainage plane able to do its job
Reversing the shingle-lap order of the flashing tape, which sends water into the wall instead of out of it
Using standard fasteners and hardware not rated for the salt content in the local air, leading to early corrosion
Installing before the wall is truly ready, then having to patch flashing details around already-set trim

Every one of these is avoidable with a crew that treats the flashing sequence as non-negotiable, even when the framing schedule is tight.

Caring for New Windows Through the Wet Seasons Ahead

A properly installed new-construction window shouldn't need much attention for years, but it's worth knowing what to watch for as the house goes through its first few winters. Check sills and trim periodically for green staining or standing moisture — that's an early sign water is sitting where it should be draining. Keep an eye on caulking at the interior trim line, since settling in a new build can occasionally open a hairline gap in the first year or two. And if you notice a window sticking or not latching the way it did when new, it's worth a look before assuming it's just the house settling — sometimes it's a sign a shim moved or a fastener backed out, both easy fixes if caught early.

If you're planning new construction, an addition, or a full exterior tear-off in Aldergrove and want windows installed by a crew that already knows this stretch of the border, the flashing details this climate demands, and the paperwork that comes with building on the BC side of the line, we're glad to walk the plans with you. Reach out for a free, no-pressure estimate — there's a form below.