Semiahmoo Siding Marietta sits in the shoreline reach of Whatcom County near Semiahmoo, and the housing stock here reflects decades of different building eras stacked next to each other — older cottages and modest single-story homes from before modern window sizing was standardized, mixed in with additions, remodels, and newer builds that opened up walls for water views. That mix means a straight "order the same size and swap it" replacement often isn't an option. More often than not, the opening itself is the variable, not just the window going into it.
We treat custom windows as their own category of work, separate from a standard stock replacement. The measuring, the flashing sequence, the lead time, and the installation details all change once a window stops being a common off-the-shelf size or shape. In a community like Marietta, where salt air, driving rain, and a long moss season are part of normal conditions, those details carry more weight than they would a few miles inland.
Why Marietta Homes End Up Needing Custom Windows
A few patterns come up again and again in this community. Older homes were framed to whatever dimensions made sense at the time, before manufacturers settled on standard sizes, so a true like-for-like replacement often means either a custom order or reframing the opening to accept a stock unit. Additions and interior remodels create new openings that don't match anything original to the house. And homes updated to take advantage of water and open-sky views frequently call for picture windows, bay windows, or oversized units sized for the view rather than for whatever happens to be easy to stock.
None of that makes a project unusual for us — it's routine work in a community like this. It does mean the job starts with careful field measurement and an honest conversation about lead time, since a genuinely custom unit is built to order rather than pulled off a shelf.
The Climate Factor Custom Windows Can't Ignore
Being close to the water puts Marietta homes in a tougher environment than the standard manufacturer installation guidance assumes. Salt-laden air accelerates corrosion on hardware, fasteners, and lower-grade frame components faster than a drier, more sheltered setting would. Storms push rain sideways into wall assemblies and window flashing instead of letting gravity carry it straight down, so water finds gaps and laps that would never get tested somewhere calmer. And the shade, humidity, and mild temperatures common to this stretch of Whatcom County support a moss and mildew season that can run most of the year on north-facing walls and trim.
Custom windows raise the stakes on all of that. A bay window has more perimeter that needs to be flashed correctly. A large picture window has more glass area for wind load to push against. A wider sill has more surface for water to sit on if it isn't sloped and detailed the right way. None of this rules custom windows out for a Marietta home — it means the installation has to account for the added complexity instead of treating it like a routine stock swap.
Where the Risk Actually Concentrates
The glass and frame material are rarely what fails first on a well-built custom unit. It's the transition points — where a bay window's roof ties into the main wall, where a wide sill meets the siding below it, where a reframed opening meets the original wall assembly — that take the real hit over time. 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 on-site.
Custom Window Types We See in Marietta
- Non-standard replacement sizes — matching an opening in an older home that predates modern manufacturer sizing standards
- Bay and bow windows — projecting units that add interior space and sightlines, but require their own roof, support, and flashing system
- Picture and large-format windows — fixed units used to open up a water or sky view, with 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 sightline 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 rather than 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 Marietta homes, and account for what the finished trim and flashing will require in terms of clearance. Because custom units are built to order, this is also where we set realistic expectations on lead time — a custom window generally takes longer to arrive than a stock size, and we'd rather say so upfront than let it surprise you mid-project.
Opening Prep and Structural Considerations
Larger custom units, bay windows in particular, 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 homes in this area, this step is also where we typically 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 Marietta's exposure. 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 in front of us, not a generic template pulled from a manufacturer's installation sheet.
Finish and Trim Integration
Custom windows often sit in visually prominent spots — a bay window facing the water, a picture window centered on a view — 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 after the fact.
Practical Checklist Before You Order
- 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'll 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 in Marietta. 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 — it's a trade-off worth discussing against your specific opening and budget, not a one-size answer.
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
Costs and Trade-Offs: Custom vs. Stock Windows
| 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 homes, 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.
Why a Local Marietta Crew Matters
Manufacturer installation guidance is written for average, standard-size conditions in a moderate climate. Custom windows in Marietta rarely fit that description, and neither does the exposure here — salt air, driving rain, and a long wet season stack the deck against a shortcut installation more than they would somewhere drier and calmer. A crew that has actually built out bay windows, reframed odd-sized openings, and flashed large view windows in this part of Whatcom County 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 Marietta home, planning an addition, or looking at a bay or picture window to make more 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 in Marietta and the surrounding Semiahmoo area — use the form below to get a time on the schedule.