Bellingham Roofing "Custom windows" covers more ground than most homeowners expect. It's not just picture windows and bay bump-outs — it's any window that isn't a stock size or shape sitting on a manufacturer's shelf. In Birchwood, that includes older homes with openings framed before window sizing was standardized, additions and remodels that create rough openings nothing off-the-rack quite fits, and specialty shapes like arched or oversized units chosen for light or a view. Whatever the reason a window in Birchwood ends up custom, it still has to survive Bellingham's marine climate — salt air, driving rain, and a moss season that runs long through the wetter months. This page walks through what that actually requires, from why custom sizing comes up so often in this neighborhood to how we handle the job from first measurement to final walkthrough.
Why Birchwood Homes End Up Needing Custom Windows
A handful of things push window projects in Birchwood out of stock-size territory more often than in a newer subdivision built on a single standardized plan. Older homes in this part of Bellingham were framed to whatever dimensions made sense to the builder at the time, well before window manufacturers agreed on common sizing — so a straight swap-in replacement isn't always possible without either a custom-built unit or reframing the opening, and reframing adds cost and disruption most homeowners would rather avoid. Additions and remodels create their own openings that don't match anything original to the house. And a fair number of homes in and around Birchwood were designed with picture windows, bay windows, or slightly oversized openings meant to bring in more light on a shaded lot — none of which are stock dimensions to begin with.
None of that is unusual work for us. It's a routine part of window projects in this part of Whatcom County. But it does change how the job starts: with careful field measurement of the actual opening, an honest conversation about what that opening can support, and realistic expectations on timeline, since custom units are built to order rather than pulled from a warehouse shelf.
The Climate Factor Custom Windows Can't Ignore
Bellingham sits close enough to the water that salt-tinged marine air is a real, ongoing factor on window hardware, fasteners, and lower-grade frame components — not something isolated to homes right on the shoreline. Over years of exposure, that air speeds up corrosion on anything not built or finished to handle it. Add to that a weather pattern where rain rarely just falls straight down; storms off the Pacific push it sideways into wall assemblies, testing flashing and seals in ways a calmer inland climate never would. And on shaded or north-facing sides of a property, which describes a good number of lots in Birchwood, a long moss season settles in and holds moisture against sills, trim, and cladding for months at a stretch.
Custom windows raise the stakes on all three of those factors at once. A larger picture window or a bay window projection has more perimeter that needs to be flashed correctly and more glass area for wind load to act against. An arched or specialty-shaped opening involves curved or angled cuts into the surrounding wall assembly, which are simply harder to flash cleanly than a plain rectangular opening. None of this means custom windows are the wrong call for a Birchwood home — it means the installation has to account for that added complexity rather than treating it like a routine stock swap.
Where the Risk Actually Lives
On most custom window failures we get called out to look at, the glass and the frame material itself are rarely the problem. It's the transition points — where a wide picture-window sill meets the siding below it, where an arched top gets cut into the surrounding wall, where a bay or bow projection ties back into the main structure. Those spots need extra flashing attention, and they're also exactly the spots a rushed install is most likely to shortcut, because doing them right takes real time that a faster job simply skips.
Custom Window Types We Build For
"Custom" isn't one product — the approach changes depending on what's actually being replaced or added.
- Non-standard replacement sizes — matching an existing opening in an older Birchwood home that predates modern window sizing standards
- Arched, angled, or specialty-shaped openings — architectural features that show up on older and custom-built Bellingham homes, requiring custom-cut units and matching flashing details
- Picture and large-format windows — fixed units used to maximize light on a shaded lot, with more glass area to manage for both wind load and moisture
- Bay and bow windows — projecting units that add usable interior space but need their own roof, structural support, and flashing system
- Matched sets for additions or remodels — new windows built to sightline correctly with the existing windows on the rest of the house
- Egress and code-driven replacements — openings that need to meet current bedroom egress requirements, which sometimes means enlarging or reshaping an existing rough opening
What a Correct Custom Window Job Involves
Getting a custom window right is a system-level job, not just ordering the correctly sized unit and setting it in the wall. Each step below is where a correct install and a future leak part ways.
Field Measurement and Verification
Stock windows can sometimes be ordered off a rough estimate. Custom units can't — the opening gets measured precisely, and on older Birchwood homes we also check the opening for square, level, and any settling or rot that would change how the new unit needs to be built or installed. Ordering before that verification is how homeowners end up with a beautiful custom window that doesn't actually fit the wall it was built for.
Removal and Opening Prep
The old window and any surrounding damaged material comes out cleanly, and the opening gets a real inspection at that point — this is often the first time hidden water damage around an old sill or header becomes visible. Framing repairs happen here, before anything new goes in, not after.
Flashing and Weatherproofing
This is the step that matters most in Bellingham's climate. A window opening needs a properly lapped weather-resistive barrier, sill pan flashing that directs any water that gets past the window back outward rather than into the wall cavity, and head flashing integrated with the siding above it. On a bay, bow, or picture window, that flashing plan has to extend around a larger and more complex perimeter than a standard opening.
Setting and Anchoring the Unit
Custom units are heavier and often larger than stock windows, and they need to be anchored to manufacturer specification so they hold their shape and seal under wind load rather than racking or flexing over time. A bay or bow window additionally needs proper structural support underneath the projection — it isn't just fastened to the wall opening like a standard flat window.
Interior and Exterior Finish Work
Trim, insulation around the frame, and interior sill work all have to be finished correctly for the window to perform the way it's rated to. Gaps left around the frame undercut both the energy performance and the weather seal, regardless of how good the window itself is.
Our Process, Start to Finish
- In-person consultation and measurement: We look at the actual opening and talk through what's realistic given the home's age and condition, rather than quoting from a photo or a rough guess.
- Written estimate: A clear, itemized bid covering the window unit, flashing and weatherproofing scope, structural work if needed, and finish work — not a single lump-sum number.
- Ordering and lead time: Custom units are built to order, so we set expectations upfront on how long fabrication and delivery will realistically take before installation can start.
- Removal and opening inspection: The old window comes out, and we address anything unexpected we find in the opening before moving forward.
- Installation and weatherproofing: The new unit goes in with flashing and sealing built to handle Bellingham's wind-driven rain and marine air, not just a generic caulk-and-set approach.
- Final walkthrough: We review the finished window with you in person, check operation and seal, and clean up the site before considering the job done.
Costs and Trade-Offs: Custom vs. Stock
| Factor | Stock Window | Custom Window |
|---|---|---|
| Fit | Only works if the opening matches a standard size | Built to match the actual opening, including odd or older dimensions |
| Lead time | Often available faster, sometimes in stock | Built to order — realistic lead times matter for scheduling |
| Upfront cost | Generally lower per unit | Higher per unit, but avoids the added cost of reframing an opening to fit a stock size |
| Shapes available | Limited to standard rectangular profiles | Arched, angled, bay, bow, and oversized shapes possible |
| Flashing complexity | Straightforward on a standard rectangular opening | More perimeter and often more complex geometry to flash correctly |
The honest comparison usually isn't "custom costs more than stock" — it's "custom costs more than stock, or reframing an opening to accept a stock window costs more than expected." For a lot of older Birchwood homes, once reframing labor is factored in, a properly sized custom unit ends up being the more practical option, not just the more expensive one on paper.
Materials and Frame Options Worth Understanding
Frame material matters more on custom units simply because there's more surface area exposed to Bellingham's weather over the life of the window.
| Frame Material | How It Handles This Climate |
|---|---|
| Vinyl | Budget-friendly and low-maintenance, though lower-grade vinyl can become brittle over many years of damp cycling; quality varies significantly by manufacturer |
| Fiberglass | Dimensionally stable through temperature and moisture swings, holds up well on larger custom units where a picture or bay window sees more expansion and contraction |
| Wood (clad or unclad) | Strong appearance for period-appropriate homes, but unclad exterior wood needs real maintenance discipline in a climate with this much sustained moisture |
| Aluminum | Strong and slim-profile, but a poor insulator unless thermally broken, and more prone to condensation in a cool, damp climate like Bellingham's |
We'll talk through which material makes sense for the specific opening, the home's style, and how much long-term maintenance you actually want to take on — there isn't one right answer for every project.
A Practical Checklist Before You Choose a Window Contractor
- Do they field-measure the actual opening in person before quoting, rather than estimating from a description?
- Does the estimate specify sill pan flashing and weatherproofing details, not just "new window installed"?
- Are structural support requirements for bay, bow, or oversized units addressed explicitly in the bid?
- Do they carry current WA contractor licensing, liability insurance, and workers' compensation?
- Can they explain realistic lead times for a custom-order unit rather than promising a stock-window timeline?
- Does the bid separate the manufacturer's product warranty from their own workmanship warranty on installation?
Why Hiring a Crew That Already Works in Birchwood Matters
A crew that regularly works on homes in and around Birchwood has already seen how salt air corrodes underspecified hardware, how wind-driven rain finds gaps in a poorly flashed sill, and which sides of a house hold moss longest through the wet months. That's practical knowledge that shows up in dozens of small decisions over the course of a custom window project — decisions a crew unfamiliar with this specific stretch of Whatcom County might not think to make at all.
It also matters after the installation is finished. A workmanship warranty only means something if the company behind it is still around and reachable years later, which is one more reason to favor a contractor with an established, ongoing presence in Bellingham over one passing through the region for a single project.
If you're weighing a custom window project for a Birchwood home, we're glad to come take a look, measure the opening, and give you an honest, no-pressure written estimate — no obligation attached. Use the form below to request a free estimate.