Ferndale Building on Semiahmoo Means Building for the Water
Semiahmoo sits out on its own spit, with Semiahmoo Bay on one side and Drayton Harbor and the Strait of Georgia influence close by. That's a beautiful place to build a home, and it's also one of the more demanding window environments in Whatcom County. Salt-laden air moves through constantly, wind-driven rain comes in sideways off the water during fall and winter storms, and the long gray stretch between October and April keeps everything damp long enough for moss and mildew to take hold on anything that doesn't shed water cleanly. New-construction windows here have to be selected and installed with all of that in mind from day one, not corrected for later.
We install new-construction windows for builders and owner-builders working in Semiahmoo and the surrounding Ferndale and Blaine area, and we treat the coastal exposure as a design input, not an afterthought.
New-Construction Windows vs. Replacement Windows — Why the Difference Matters
New-construction windows have a nailing fin (flange) built into the frame and are installed before the siding goes on, integrated directly into the wall's water-resistive barrier and flashing system. Replacement windows are built to fit into an existing rough opening with the exterior trim left in place, and they rely on a different sealing approach entirely.
On a new build, you get the chance to do this correctly the first time — proper flashing sequence, correct fastener spacing, and a window that's mechanically tied into the wall assembly rather than caulked into it after the fact. That's the advantage of new construction, and it's also where the most damage gets done if the sequence is rushed or skipped.
What a Correct New-Construction Install Actually Involves
- Rough opening checked for square, level, and correct size before the window ever shows up on site
- Sill pan flashing installed first, sloped to drain water back out and away from the framing
- Window set, shimmed for square, and fastened per the manufacturer's schedule — not just "enough to hold it"
- Jamb and head flashing lapped correctly over the sill pan and under the water-resistive barrier, shingle-style, so water always moves down and out
- Sealant used only where the manufacturer specifies it — over-sealing traps water just as badly as under-sealing
- Interior air seal completed separately from the exterior water seal (they do two different jobs)
What Semiahmoo's Climate Adds to That Standard
Salt Air and Hardware Corrosion
Salt-laden air corrodes untreated fasteners, cheap hinge hardware, and low-grade cladding metals faster than most homeowners expect — sometimes within a few years on a directly exposed wall. On Semiahmoo builds we pay attention to fastener material and window hardware finish, not just the frame itself, because the frame can look fine while the hardware underneath is already failing.
Wind-Driven Rain
Storms off the water don't just fall — they push. Wind-driven rain finds every gap in a flashing sequence that a calm-weather rain never would. This is the single biggest reason we won't shortcut the flashing detail on a Semiahmoo job, even on a wall that looks fully protected by roof overhang. Water can travel sideways further than people assume.
The Long Moss and Moisture Season
Whatcom County's damp season runs long, and anywhere moisture sits — a horizontal sill, a poorly sloped flashing lap, a shaded north wall — moss and mildew will eventually show up. Correct sill pan slope and drainage are what keep that moisture moving instead of pooling, which is a bigger factor in long-term window performance here than in drier parts of the state.
Frame Material Comparison for Coastal New Construction
| Material | Coastal/Salt-Air Performance | Maintenance | Typical Trade-Off |
|---|---|---|---|
| Vinyl | Good — won't corrode or rust | Low; occasional cleaning | Frame color/finish is fixed for life of the window |
| Fiberglass | Very good — stable in temperature swings and salt exposure | Low | Higher upfront cost than vinyl |
| Aluminum (uncoated) | Poor unless marine-grade coated — prone to pitting near salt air | Higher; coating needs monitoring | Slim sightlines, but corrosion risk without the right finish |
| Wood (unclad) | Weak without a durable exterior cladding — moisture and salt both work against bare wood | High; regular refinishing | Best appearance option, but highest upkeep near the water |
| Wood-clad (vinyl or aluminum exterior) | Good — exterior face protected, interior keeps wood look | Moderate | Cladding integrity at joints matters more here than inland |
We'll talk through frame material as part of the estimate, but on a directly exposed Semiahmoo lot, we generally steer builders toward vinyl or fiberglass, or wood-clad if the interior look calls for it. Bare aluminum and unclad wood aren't things we'll refuse to install, but we'll be upfront about the maintenance burden they carry in this specific exposure before you commit to them.
How the Process Works on Your Job
- Plan review — we look at window schedule, rough opening sizes, and wall assembly before framing is even finished, so there are no surprises when windows arrive.
- Site coordination — we work directly with your general contractor or, if you're owner-building, with you, to time delivery and install around the framing and weather-barrier sequence.
- Flashing and install — sill pan, window set, and flashing lap done in the order above, on every opening, no exceptions for "it's under the eave so it'll be fine."
- Documentation — we photograph the flashing sequence on each opening before siding closes it in, since that's the one point in the build where anyone can actually verify the work was done right.
- Final check — every window operates, locks, and seals correctly before we sign off, and before siding crews or trim carpenters move in behind us.
Coordinating With Your Builder or GC
New-construction window work only goes smoothly when it's scheduled correctly against framing, weather-resistive barrier installation, and siding. We're used to working as a sub on someone else's build schedule — showing up when the rough openings are ready, not before, and getting out of the way so siding or trim can follow without a gap in the timeline. If you're managing the build yourself, we'll walk you through what sequence and lead time to plan for so windows aren't sitting exposed to weather longer than they need to be.
Energy Code and Performance Considerations
Washington's energy code sets minimum performance requirements for new-construction windows (U-factor and, depending on the compliance path your builder is using, solar heat gain), and those numbers get checked at inspection. Beyond meeting code, a well-sealed, correctly flashed window is the bigger factor in how the house actually performs day to day — a window that meets the U-factor requirement on paper but leaks air at the frame because of a rushed install will still feel drafty and cost more to heat. We install to the flashing and sealing standard first, because that's what determines whether the code-rated performance actually shows up in the finished house.
Before Siding Closes In: What to Check
- Sill pan flashing is visible and sloped outward — not flat, not sloped toward the house
- Flashing tape or house wrap laps follow shingle order (each layer overlaps the one below it)
- No exposed nailing fin edges or gaps at the corners
- Window operates smoothly — opens, closes, and locks without forcing
- Sealant is present only where specified, with no gaps or globs covering flashing that should stay visible
- Photos or notes exist documenting the flashing detail before it's covered by siding
If your builder or window crew can't answer questions about any of these points, that's worth pausing on before the wall gets closed up — it's far cheaper to fix a flashing detail before siding goes on than after.
Why It Matters to Hire a Crew That Already Works Semiahmoo
Window installation technique doesn't change from one town to the next, but judgment calls do — how much attention a given wall orientation needs, which details are worth extra time because of direct wind and salt exposure, and which coastal shortcuts cause problems five years down the road instead of five months. A crew that's done new-construction window work on the spit and along the Whatcom County shoreline has already seen where that judgment matters. That's not something you can get from a crew that mostly works inland and treats every job the same way.
If you're planning a new build in Semiahmoo, we're glad to walk the plans with you or your builder and put together a straightforward estimate — no pressure, no hard sell, just a clear look at what your windows will need for this site. Use the form below to get started.