Blaine Roofing Semiahmoo sits out on a narrow spit between Semiahmoo Bay and Drayton Harbor, right at the edge of Blaine and the Canadian border. It's a mix of older cottages and cabins that have been added onto or converted for year-round living over the decades, alongside newer condos and resort-style construction built to take advantage of water views on both sides of the spit. That combination — old, non-standard framing next to newer builds chasing a view — is exactly why "custom" comes up so often on window projects out here, rather than as an occasional exception.
We treat custom windows as their own category of work, separate from a straightforward stock replacement. The measuring, the flashing sequence, the lead time, and the installation details all change once a window stops being a standard size or shape. On an exposed spit property where salt air and wind-driven rain are part of daily conditions, getting those details right matters more than it would a few miles inland in Blaine proper.
Why Semiahmoo Homes End Up Needing Custom Windows
A few patterns show up again and again on the spit. Older cottages were framed to whatever dimensions made sense at the time, long before manufacturers standardized common sizes, so a like-for-like replacement often means ordering custom or reframing the opening rather than pulling something off a shelf. Additions and remodels on smaller lots create new openings that don't match anything original to the house. And because Semiahmoo has water in more than one direction, homeowners building or renovating here frequently want picture windows, bay windows, or oversized units sized to catch a specific view rather than sized for convenience.
None of that makes a project unusual for us — it's routine work in this neighborhood. It does mean the job starts with careful field measurement and an honest conversation about lead time, since a custom unit is built to order, not pulled from inventory.
The Climate Factor Custom Windows Can't Ignore
Salt Air From Two Directions
Because the spit is bordered by water on more than one side, homes here take on salt-laden air from multiple directions instead of one prevailing exposure. That accelerates corrosion on hardware, fasteners, and lower-grade frame components faster than a drier, more sheltered site would see. Every hinge, lock, and fastener on a custom window has to be chosen with that in mind, not swapped out later once it starts showing rust.
Wind-Driven Rain With Nothing to Break It
With almost no windbreak, storms push rain sideways into wall assemblies and window flashing rather than letting gravity do the work. That's a heavier moisture load than the region's rainfall totals alone suggest, and it finds gaps that would never get tested on a calmer, more sheltered lot. A custom window with more perimeter to flash — a bay window, a wide sill, a resized opening — gives that wind-driven rain more places to test the installation.
A Moss Season That Runs Most of the Year
Mild temperatures, near-constant humidity, and shaded north-facing walls add up to a moss and mildew season that runs most of the year across this part of Whatcom County, and Semiahmoo's waterfront location doesn't shorten it. It shows up on trim, sills, and any porous material slowest to dry, which is worth factoring into finish choices on a custom unit that will sit in a shaded or damp spot.
Where the Risk Actually Lives
The glass and frame material are rarely what fails first on a well-built custom window. It's the transition points — where a bay window's roof meets the main wall, where a wide sill meets the siding below it, where a reframed opening meets the original wall assembly. Those spots need extra flashing attention, and they're also the spots a rushed installation is most likely to shortcut, because doing them correctly takes real time.
Custom Window Types We See on the Spit
- Non-standard replacement sizes — matching an opening in an older cottage or cabin that predates modern sizing standards
- Bay and bow windows — projecting units that add interior space and view lines toward the bay or harbor, but need their own roof, support, and flashing system
- Picture and large-format windows — fixed units used to maximize a water view, with wide sightlines and more glass area to manage structurally
- Reframed or resized openings — where the existing rough opening needs correction before any new unit can go in cleanly
- Matched sets for additions — new windows sized to line up correctly with existing windows on an older home
- Egress and code-driven openings — bedroom or living space additions where the minimum opening size is set by code, not preference
What a Correct Custom Window Job Involves
Measuring and Ordering
Custom work starts with precise field measurement, not a catalog lookup. We measure the actual opening, note any out-of-square or out-of-level conditions common in older Semiahmoo cottages, and account for what the finished trim and flashing will need in terms of clearance. Because custom units are built to order, this is also where we set realistic expectations on lead time — custom windows generally take longer to arrive than stock sizes, and we'd rather say so upfront than surprise you mid-project.
Opening Prep and Structural Considerations
Larger custom units, bay windows especially, sometimes need structural support beyond what a standard opening requires, since they carry more weight and project outward from the wall. We evaluate that during the assessment, not after demolition has started. On older spit homes, this step is also where we often find out whether the original framing or flashing around the opening needs repair before a new unit goes in.
Flashing and Weatherproofing
This is the step that matters most given the exposure here. Every custom shape changes how flashing has to be sequenced — a bay window's roof needs its own weatherproofing separate from the wall flashing below it, a wide sill needs to shed water outward instead of letting it pool, and a resized opening needs new flashing tied cleanly into the surrounding wall rather than patched around the old detail. We build the flashing plan around the specific opening, not a generic template pulled from a manufacturer's installation sheet.
Finish and Trim Integration
Custom windows on the spit often sit in visually prominent spots — a bay window facing the harbor, a picture window centered on the bay — so the trim and finish work has to match the rest of the exterior cleanly. We plan that integration before the window arrives so the finished result reads as intentional rather than added on.
- Confirm the opening was field-measured, not estimated from old plans or a rough guess
- Ask what the flashing plan looks like for your specific opening shape, not a generic answer
- Get a realistic lead time in writing before committing to a schedule
- Ask whether the opening needs structural review, especially for bay or oversized units
- Confirm what's covered under warranty — the window unit and the installation labor are often separate
- Ask how trim and finish will be matched to the surrounding siding
Frame Materials for This Climate
Frame material matters even more on a custom unit, since a larger or more exposed window has more surface area for salt air and moisture to work against over time. We walk through the honest trade-offs for your specific opening rather than defaulting to whatever's fastest to install. In general, fiberglass and vinyl frames hold up to sustained coastal moisture with less ongoing upkeep than an all-wood exterior finish, which is why we lead with them on weather-facing custom installs at Semiahmoo. Wood-clad interiors paired with a low-maintenance exterior cladding can still be the right call when the interior look matters and the exterior is properly protected — that's a trade-off worth discussing against your specific opening and budget, not a one-size answer.
Costs and Trade-Offs: Custom vs. Stock
| Factor | Stock Window | Custom Window |
|---|---|---|
| Lead time | Often available relatively quickly | Built to order — expect weeks, not days, depending on complexity |
| Fit | Standard sizes only; reframing needed if the opening doesn't match | Matched to the exact opening or design intent |
| Flashing complexity | Straightforward, well-documented rectangular details | Shape-specific — bay roofs, resized openings, or wide sills each need their own plan |
| Structural review | Rarely needed for a like-for-like swap | Often needed for bay, bow, or oversized units |
| Cost | Lower, especially for common sizes | Higher, reflecting manufacturing and labor complexity |
| Best fit | Simple replacements in standard, already-correct openings | Older cottages, additions, view-driven design, or non-standard framing |
What actually moves price on a custom job is fairly consistent: overall size and glass area, shape complexity, whether structural framing needs to be added or corrected, frame material, the condition of the existing opening, and how many units are being ordered together. We won't quote a number without seeing the opening in person, but we'll walk through which of those factors apply to your project before you commit to anything.
Our Process, Start to Finish
- On-site assessment — we measure the opening, check square and level, and evaluate any structural or flashing concerns specific to its shape or size
- Honest recommendation — custom order, modified stock size, or opening reframe, explained with the reasoning behind it
- Ordering and lead time — a realistic timeline for the custom unit to arrive, since it isn't a same-week job
- Removal and opening prep — the old unit comes out carefully, and any hidden framing or flashing issues get addressed before the new window goes in
- Installation and flashing — the new unit is set, shimmed, and flashed to a sequence built for its specific shape and size
- Trim and finish — exterior trim is integrated to match the surrounding siding and architecture
Why a Local Semiahmoo Crew Matters
Manufacturer installation guidance is written for average, standard-size conditions in a moderate climate. Custom windows on the spit rarely fit that description, and neither does the exposure here — salt air from two directions, wind-driven rain, and a long wet season stack the deck against a shortcut installation more than they would somewhere calmer. A crew that has actually built out bay windows, reframed odd-sized cottage openings, and flashed large view windows on this specific stretch of Whatcom County coastline knows which parts of a manufacturer's guidance are non-negotiable here, and where extra time on flashing or sealant is worth it even when it isn't strictly required elsewhere.
That experience shows up in decisions that don't come up in a sales conversation — how a bay window's roof ties into the main wall's drainage plan, how much lap a flashing course needs on a resized opening, when a sill needs a sloped composite cap instead of relying on caulk alone. Those are the details that decide whether a custom window is still performing cleanly in fifteen years or showing drafts and soft trim in five.
What to Ask Before Hiring for Custom Window Work
- Ask to see examples of custom shapes or sizes they've actually installed, not just standard replacements
- Ask how they sequence flashing for your specific opening shape
- Confirm current Washington contractor licensing and insurance
- Get a written scope of work and a realistic lead time before signing anything
- Ask how labor and the window unit are each covered under warranty
If you're weighing a custom window for an older Semiahmoo cottage, planning an addition, or looking at a bay or picture window to make the most of a water view, it's worth having someone look at the actual opening before you start pricing units. We offer free, no-pressure estimates for custom window projects on the spit and throughout the Blaine area — use the form below to get a time on the schedule.