Bellingham Siding Windows Built for Sehome's Older Housing Stock
Sehome is one of Bellingham's older, more established neighborhoods, with a housing mix that ranges from early-1900s craftsman-era homes near Western Washington University to mid-century remodels and newer infill construction closer to Sehome Hill. That mix matters when it comes to windows. A lot of these homes still have original wood-frame windows, single-pane replacements from decades past, or a patchwork of upgrades done room by room over the years. Whatcom County's climate has not been kind to any of it. Salt air drifting in off Bellingham Bay, near-constant driving rain through fall and winter, and a moss and mildew season that can stretch six months or more all work steadily on window frames, seals, and sills.
Custom windows in this context aren't about a showroom upgrade. They're about matching new units to openings that were often built by hand, in a home that has settled and shifted over the better part of a century, in a climate that punishes anything less than a tight, correctly flashed installation.
What "Custom" Actually Means Here
Custom doesn't mean expensive for its own sake — it means the window is sized, shaped, and detailed to fit the actual opening and the actual house, rather than forcing a stock size into a space it wasn't made for. In Sehome specifically, that usually shows up in a few recurring ways:
- Older homes with slightly out-of-square openings after decades of settling, which stock replacement windows won't seat into cleanly
- Non-standard shapes — arched, angled, or oversized openings on craftsman and early-20th-century homes
- Mixing new construction techniques into a remodel where the original wall assembly wasn't built for modern window flanges
- Matching trim profiles and sightlines on a street where the home's original character is part of its value
A correct custom job starts with an accurate measurement of the actual rough opening — not the old window's nominal size — and a decision about whether the project is a full-frame replacement (removing down to the framing) or an insert replacement (fitting a new window into the existing frame). That decision affects both cost and how well the finished window performs against wind-driven rain, which is the main threat in this part of Whatcom County.
Full-Frame vs. Insert Replacement
| Factor | Insert Replacement | Full-Frame Replacement |
|---|---|---|
| Best for | Sound existing frame, no rot, budget-conscious upgrade | Rotted or damaged frame, changing window size or shape, older homes with settling issues |
| Weatherproofing access | Limited — relies on existing frame and flashing | Full access to re-flash and seal to the sheathing |
| Disruption | Lower — faster install, less exterior/interior work | Higher — trim, siding, and interior casing often need to be opened up |
| Typical lifespan of the fix | Good, if the existing frame is truly sound | Longer — you're not building on top of an unknown |
On a lot of Sehome homes, especially anything pre-1960, we lean toward at least inspecting down to the framing before committing to an insert. A window that looks fine from the street can be sitting in a frame with years of slow moisture damage behind the trim — something that's common wherever driving rain and salt air are part of the daily weather pattern.
Why Local Climate Drives the Installation Details
Bellingham doesn't get hurricane-force weather, but it gets something arguably harder on a window: sustained, wind-driven rain over long stretches, combined with salt-laden air off the bay that accelerates corrosion on hardware and fasteners. Add in a moss and algae season that keeps exterior surfaces damp for months at a time, and you have conditions that expose bad flashing or a rushed caulk job within a year or two, not a decade.
The details that actually matter in this climate
- Flashing sequence — sill pan flashing installed correctly, with side and head flashing lapped in the right order so water sheds outward, never trapped behind the window
- Sealant compatibility — using sealants and materials rated for sustained UV and moisture exposure, not a generic caulk that hardens and cracks after one wet season
- Corrosion-resistant hardware — fasteners and cladding hardware that hold up against salt air rather than staining or seizing within a few years
- Drainage path — a clear route for any incidental moisture to exit the assembly instead of pooling at the sill
None of this is visible once the trim goes back on, which is exactly why it's worth asking a contractor to walk through it before work starts, not after.
Our Installation Process
We keep the process straightforward and try not to leave a Sehome home more exposed than it needs to be during a Bellingham winter.
- On-site assessment. We measure actual rough openings, check the condition of existing framing and sheathing, and identify any rot or moisture damage before ordering anything.
- Product selection. We go over frame material, glass packages, and sizing options based on the home's age, exposure, and your budget — matching new windows to the existing character where that matters to you.
- Removal and inspection. Once the old window comes out, we get a direct look at the framing. If there's hidden damage, we flag it and discuss options before closing anything back up.
- Flashing and installation. Sill pan, side, and head flashing go in per manufacturer specs and best practice for this climate, then the window is set, shimmed level and square, and fastened.
- Sealing and insulation. Gaps are insulated and sealed on both the exterior and interior side to control both moisture and air leaks.
- Trim and finish. Interior and exterior trim is reinstalled or replaced to match the home, and the site is cleaned up.
We try to schedule around weather windows where we can, since an open rough opening during a stretch of driving rain is exactly the situation you don't want on an occupied home.
Common Problems We Find on Sehome Homes
A few issues come up often enough in this neighborhood that they're worth mentioning directly:
- Original single-pane wood windows with failing glazing putty, leading to drafts and visible moisture between panes on any later double-glazed replacements
- Caulk-only "repairs" from a previous owner where a gap was sealed over instead of properly flashed, hiding water intrusion until trim or siding is opened up
- Sills and lower frame corners with early rot, especially on the weather-exposed sides of the house, from years of moss and standing moisture
- Mismatched replacement windows installed one at a time over the years, leaving inconsistent sightlines and performance across the house
None of these are unusual for a neighborhood with this much older housing stock — they're just the kind of thing that gets worse quietly until a window is opened up for replacement.
What to Check Before You Hire
Whether you use our crew or someone else, a few questions will tell you a lot about whether a contractor is set up to do this correctly in Bellingham's climate:
- Do they inspect the framing before quoting, or just measure the existing window opening?
- Can they explain their flashing sequence, not just "we seal it up good"?
- Are they licensed and insured to work in Washington, and can they show it?
- Do they have experience with the age and construction type of your specific home, not just newer builds?
- Will they tell you honestly if a window is beyond a simple insert replacement, even if that's a harder conversation?
A crew that already works regularly in Sehome and the surrounding Bellingham neighborhoods has usually already seen your home's era of construction, framing quirks, and typical failure points — which means fewer surprises once the old window comes out.
Why a Local Crew Matters Here
Window installation isn't a one-size-fits-all trade, and Whatcom County's weather isn't forgiving of shortcuts. A crew that knows Sehome's housing stock — the older craftsman frames, the settling patterns, the exposure each side of the house gets to wind-driven rain off the bay — brings judgment to the job that a generic installer working from a national playbook doesn't have. That shows up in small decisions: which openings need a full-frame approach instead of an insert, where moss buildup is a sign of a bigger moisture problem, and which flashing details matter most on a given elevation of the house.
If you're weighing a window project in Sehome — whether it's one problem window or a full house's worth of aging originals — we're happy to come take a look, walk through what we find, and give you a straight assessment of what the job actually involves. Reach out for a free, no-pressure estimate using the form below.