Custer Building on Semiahmoo Means Building Against Wind and Salt From Day One
Semiahmoo sits out on open water, exposed to wind and salt spray in a way most Whatcom County building sites aren't. If you're framing a new home or a large addition out there, the windows you choose and how they're installed matter more than they would a few miles inland. A window that's merely "installed to code" in a sheltered subdivision can still leak, corrode, or fog out here within a few winters. New-construction window work on Semiahmoo has to account for driving rain hitting the wall assembly at an angle, salt-laden air working on hardware and finishes, and a moss season that turns any weak point in the drainage plane into a slow, hidden problem.
This page is specifically about new-construction window installation — setting windows into a home that's still being framed or sided, not swapping old units into an existing wall. That distinction changes almost everything about how the job should be done.
New-Construction vs. Replacement: Why the Install Method Matters
In a replacement job, we're working around existing siding and trim, often using a flush-fin or pocket window to minimize disturbance to finished surfaces. New construction is the opposite situation — we're setting windows into open wall framing before siding goes on, which means we get full access to the rough opening, the weather-resistive barrier (WRB), and the flashing details underneath everything.
That access is an advantage, but only if it's used correctly. A new-construction window has a nailing flange that gets integrated directly into the WRB and flashing system — house wrap, flashing tape, sill pans, and head flashing all have to be layered in the right order, shingle-style, so water sheds outward at every layer. Done right, this is the single best opportunity a house will ever have to get water management correct at every opening. Done wrong — flange taped over the WRB instead of under it, no sill pan, flashing tape that wasn't compatible with the WRB — the mistake gets buried behind siding and doesn't show up until there's rot or interior staining, sometimes years later.
What "Correct" Actually Looks Like
On a coastal, high-wind-driven-rain site like Semiahmoo, we don't treat the minimum code flashing detail as the target — we treat it as the floor. That means:
- A sloped or pan sill flashing under every window, not just building paper folded into the opening
- Head flashing with a drip edge that projects past the face of the siding, not tucked flush
- Flashing tape rated for the temperature range and UV exposure it'll see during construction, applied in strict shingle-lap order over the WRB at the jambs and under it at the head
- Sealant used only where it belongs — as a backup to mechanical flashing, never as the primary water barrier
- Corner and kick-out flashing details reviewed at every roof-wall or deck-wall intersection near a window, since that's where wind-driven rain concentrates
Driving Rain: Why Wind Direction Changes the Detailing
Wind-driven rain doesn't fall straight down — on an exposed site like Semiahmoo it hits walls at an angle, and prevailing weather off the water tends to load certain elevations harder than others. That affects real decisions on the job: which elevations get extra flashing width, whether a window needs a deeper sill pan return, and how tight the tolerance is on flange fastening. We look at the lot's orientation to the water and prevailing wind before framing crews close in the walls, not after — because once siding is up, correcting a marginal flashing detail means tearing back out to the sheathing.
Choosing a Frame Material for a Marine Environment
Salt air is hard on hardware and finishes over time, and it's worth thinking about frame material and hardware finish before the windows are ordered, not after they're installed. There's no single "best" material for every situation — it depends on your budget, your home's style, and how much maintenance you're willing to do.
| Frame Material | Coastal Performance | Maintenance | Trade-offs |
|---|---|---|---|
| Vinyl | Won't corrode; performs well in salt air | Low — occasional cleaning | Limited color/size options at larger spans; can flex in very large openings |
| Fiberglass | Excellent — dimensionally stable, doesn't corrode or rot | Low | Higher upfront cost than vinyl |
| Aluminum-clad wood | Good exterior protection if hardware/finish is marine-rated; interior wood needs the envelope to stay dry | Moderate — depends on finish and exposure | Beautiful interior wood look, but any water intrusion at the flashing is more costly to fix |
| Bare aluminum | Prone to pitting and corrosion in salt air unless specifically marine-rated and finished | Higher | We generally steer clients away from unprotected aluminum on this stretch of coastline |
Hardware finish matters as much as frame material — look for corrosion-resistant hinges, locks, and cranks, and ask the manufacturer directly about their salt-air/coastal warranty language rather than assuming standard warranty terms apply the same way here as they would inland.
Moss Season and the Parts of the House Nobody Watches
Whatcom County's long wet season means moss and algae growth on north- and shade-facing surfaces for much of the year. Around windows, that shows up less as staining on the glass and more as slow moisture retention in the surrounding trim and siding — moss holds water against a surface far longer than bare wood or vinyl would dry on its own. A window with proper flashing and a drip edge that actually sheds water away from the wall keeps that moisture from ever building up against the opening. A window without one becomes a spot where moss and trapped moisture work on the wall assembly year-round, out of sight, until there's a problem at the interior.
How We Work With Your Builder or GC
New-construction window installs are a coordination job as much as a trade job. We work directly with the framing crew, the WRB/house wrap installer, and the siding crew so the sequence happens in the right order — windows set and flashed before siding closes in the wall, not as an afterthought once other trades are already ahead of schedule. On a Semiahmoo build, we also flag any elevation that needs extra attention for wind-driven rain before the walls are wrapped, so nobody's cutting corners under a deadline.
Our New-Construction Window Install Process
- Review the window schedule and rough openings against the plans before windows arrive
- Confirm frame material, U-factor, and hardware finish are appropriate for a marine site
- Inspect the WRB and rough opening for square, level, and proper preparation before setting anything
- Install sill pan flashing with a positive slope to the exterior
- Set the window, shim and fasten per manufacturer spec, and confirm it operates smoothly before it's flashed in
- Integrate jamb and head flashing in correct shingle-lap order over the WRB
- Apply backer rod and sealant at the interior air seal, separate from the exterior water management layer
- Photograph flashing details before siding covers them, for your records
- Final walkthrough and operation check on every unit before we leave the site
What This Costs and What Drives the Price
New-construction window installation is typically priced by the opening, and the total depends on window size, frame material, glass package, and how many elevations need extra flashing attention for wind exposure. As a general range, homeowners on this kind of coastal site should expect fiberglass and aluminum-clad wood units to run higher than vinyl for the same opening size, and larger or specialty shapes (bays, large picture windows, multi-unit combinations) to add cost beyond a standard single window. We'll give you a real number once we know the window schedule and site conditions — broad ranges online rarely mean much once wind exposure and glass package are factored in.
Why a Semiahmoo-Familiar Crew Matters
A crew that's worked this stretch of coastline knows which elevations typically take the worst of the wind-driven rain, understands how quickly moss and algae establish on north-facing trim here, and has already made the judgment calls about flashing details that a crew from a sheltered inland job might not think to make. That familiarity doesn't show up as a line item on an estimate, but it's the difference between windows that are still performing well in ten or fifteen years and ones that need trim and flashing repairs long before that.
If you're planning new construction or a major addition in Semiahmoo, we're happy to walk the site plans with you, talk through window and frame material options for your specific elevations, and give you a straightforward, no-pressure estimate. Use the form below to get started.