Birch Bay Exterior Custer is flat, open, and agricultural, sitting inland from Birch Bay and Drayton Harbor but still well within reach of the marine air and wind that move across this part of Whatcom County. It's not a neighborhood full of waterfront view homes — it's older farmhouses, acreage properties, additions built onto original structures over decades, and outbuildings converted into living space. That history is exactly why custom windows come up so often here. A lot of Custer's housing stock predates the standardized window sizes manufacturers build to today, and additions rarely line up with an off-the-shelf opening.
We're Birch Bay Exterior Co, and while our name points to the water, a good share of our window work happens a few miles inland in places like Custer. We treat custom windows as their own category of work — different measuring, different flashing sequence, different lead times — and we bring the same standards out to Custer that we hold to on the coast, because the exposure here is real even if it doesn't come with direct salt spray.
Why Custom Windows Come Up So Often in Custer
A handful of patterns repeat across this area. Older farmhouses were framed to whatever dimensions made sense at the time, long before manufacturers settled on today's standard sizing, so matching an existing opening often means ordering custom rather than assuming a stock size will fit. Additions and remodels create openings that don't match anything original to the house. Porches, mudrooms, and sunrooms added onto older homes frequently call for windows sized to the space rather than pulled from a catalog. And on acreage properties, we sometimes see homeowners wanting a larger picture or bay window to open up a view across open farmland — not a waterfront view, but a view worth designing around all the same.
None of that makes a project unusual for us. It does mean the job starts with careful field measurement and an honest conversation about lead time, since a true custom unit is built to order rather than taken off a shelf.
What Custer's Climate Does to a Custom Window
Wind-Driven Rain on Open Ground
Custer sits on flat agricultural land with very little natural wind break. Storms moving through Whatcom County push rain sideways into wall assemblies here in a way that more sheltered, tree-lined properties don't experience as often. For a custom window, that matters more than it does on a standard unit — a wider sill, a bay window's projecting roofline, or a resized opening all have more surface area and more seams for wind-driven rain to test.
Marine Air, Carried Inland
Custer doesn't take direct salt spray the way a true waterfront property does, but it's close enough to the Salish Sea that marine-influenced air still reaches it, especially during winter storms. Over years, that air accelerates corrosion on lower-grade hardware and fasteners. On a custom window with more hardware points — a larger casement, a bay unit with multiple operable sashes — that adds up faster than it would on a small single-unit stock replacement.
A Long Moss and Mildew Season
Mild, damp conditions across most of the year give moss and mildew a long growth window on shaded walls, sills, and trim throughout Whatcom County, and Custer is no exception. Wider sills and more complex trim details on a custom window create more surface area where water can sit if it isn't sloped and detailed to shed correctly.
Custom Window Situations We See in Custer
- Non-standard replacement sizes — matching an opening in a farmhouse or older home built before today's standard sizing existed
- Enclosed porches and converted spaces — mudrooms, sunrooms, or porches turned into year-round living space, sized to the room rather than to a catalog
- Bay and bow windows — projecting units that open up a farmland or garden view, with their own roof, support, and flashing needs
- Reframed or resized openings — where an existing rough opening has to be corrected before a new unit can go in cleanly
- Matched sets for additions — new windows sized to sightline correctly with the original home's existing windows
- 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
Field Measurement and Ordering
Custom work starts with measuring the actual opening on site, not working off old plans or an assumption that "it's probably standard." We check for out-of-square and out-of-level conditions, which show up often in older Custer farmhouses, and we 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 — it's generally weeks, not days, and we'd rather say that upfront than let it become a surprise mid-project.
Opening Prep and Structural Considerations
Larger custom units, especially bay or bow windows, sometimes need structural support beyond what a standard opening provides, since they carry more weight and project outward from the wall. We evaluate that during the initial assessment, not after the old window is already out. On older Custer homes, this step is also often where hidden framing or flashing issues around the original opening come to light.
Flashing Sequenced to the Shape
This is the step that matters most given how exposed Custer's open terrain is to wind-driven rain. Every custom shape changes how flashing needs 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 rather than pulling a generic template off a manufacturer's installation sheet.
Trim and Finish Integration
Custom windows often sit somewhere visually prominent — a bay window on a farmhouse facade, a matched set on a new addition — so the trim and finish work needs to read as intentional rather than tacked on. We plan that integration before the window arrives so it matches the rest of the exterior cleanly.
Practical Checklist Before You Order
- Confirm the opening was field-measured, not estimated from old plans or a 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 the trim and finish will be matched to your home's existing siding
Frame Materials Worth Considering
Frame material matters more on a custom unit, since a larger or more exposed window has more surface area for moisture and marine-influenced air 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.
| Frame Material | Strengths in Custer's Climate | Trade-Offs to Weigh |
|---|---|---|
| Vinyl | Resists rot and corrosion, lower upfront cost, low maintenance | Fewer color and custom-shape options than fiberglass on some product lines |
| Fiberglass | Very stable across temperature swings, holds paint if a custom color is wanted | Higher upfront cost than vinyl |
| Wood-clad | Interior warmth and appearance some homeowners want on farmhouse-style homes | Exterior cladding and every seal have to be right — more sensitive to installation quality in this climate |
For weather-facing custom installs in Custer, we generally lead with vinyl or fiberglass because both hold up to sustained damp, wind-driven conditions with less ongoing upkeep than an all-wood exterior finish. A wood-clad interior with a protected exterior can still be the right call when the interior look matters to a homeowner — it's a trade-off worth discussing against your specific opening and budget, not a default answer for every job.
Custom vs. Stock: What Actually Changes
| Factor | Stock Window | Custom Window |
|---|---|---|
| Lead time | Often available from local stock relatively quickly | Built to order — expect weeks, 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 already-correct, standard openings | Older farmhouses, additions, converted porches, or non-standard framing |
What actually moves price on a custom job is fairly consistent: overall size and glass area, shape complexity, whether the opening needs structural correction, frame material, the condition of the existing framing, and how many units are ordered together. We won't put a number on it 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 window comes out carefully, and any hidden framing or flashing issues get addressed before the new unit 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 rest of the home
Why a Local Crew Matters, Even Working In from Birch Bay
Custer's open, wind-exposed farmland is a different environment than the immediate waterfront, and treating it the same way would be a mistake in either direction — underestimating the wind-driven rain because there's no direct salt spray, or overbuilding for exposure that isn't there. A crew that regularly works both stretches of Whatcom County knows the difference, and knows which parts of a manufacturer's standard installation guidance are non-negotiable out here versus where local conditions call for extra attention that a generic install wouldn't include.
That shows up in decisions that don't come up in a sales conversation — how much lap a flashing course needs on an open, wind-exposed wall, whether a wide farmhouse sill gets a sloped cap instead of relying on caulk alone, how a bay window's roof ties into the drainage plan of an older farmhouse wall. Those decisions are what determine whether a custom window in Custer 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 active liability 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 Custer farmhouse, planning an addition, or converting a porch or mudroom into year-round space, 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 Custer and the surrounding area — use the form below to get a time on the schedule.