Birch Bay Siding Exterior Work Built for Sumas, Washington
Sumas sits at the far edge of Whatcom County, hard against the U.S.-Canada border, in a part of the state where the weather doesn't do anything by halves. Winters bring long stretches of low cloud and steady rain. Summers can swing from cool and damp to surprisingly warm. In between, homes sit through months of moisture exposure that most siding, trim, and roofing products were never really engineered to handle over the long haul. When we take on a project in Sumas, we're not guessing at what the exterior will face — it's the same climate pattern we work with across Whatcom County, just with its own local rhythm.
Birch Bay Siding Company works throughout the county, and Sumas is part of that service area. We show up with the same crew, the same materials, and the same standards we use everywhere else we work — not a subcontractor pulled in for a one-off job.
What the Climate Does to a Sumas Home Over Time
Whatcom County's blend of driving rain, persistent humidity, and a moss season that can stretch most of the year is hard on exteriors. A few things we see consistently on homes in this part of the county:
- Moss and algae growth on north-facing walls, roof valleys, and anywhere shade keeps a surface from drying out between rain events.
- Paint failure and swelling on wood-based siding products where moisture works into seams, butt joints, and cut edges.
- Trim and fascia rot around windows and rooflines, especially where caulking has aged out and stopped shedding water.
- Wind-driven rain intrusion at corners and penetrations during winter storm systems.
None of this is unique to Sumas — it's the reality for most of western Whatcom County — but it's exactly why the products and installation details we use matter more here than they would in a drier climate.
Why Product Choice Matters More in This Climate
A siding product that performs fine in a dry inland climate can fail early in a wet, moss-prone one. That's the core reason our company made a deliberate decision about what we will and won't install.
Why We Install Only James Hardie Fiber Cement
Birch Bay Siding Company installs James Hardie fiber cement siding exclusively. We don't offer vinyl, LP SmartSide, cedar, primed spruce, Cemplank, or Allura as alternatives. That's not because those products have no merit — each has a legitimate place in the market. It's because after years of exterior work in this climate, we settled on one system we trust to hold up and stand behind, rather than installing several products with different failure patterns and different warranty structures.
How the Alternatives Compare
| Product | What It Gets Right | Where It Struggles Here |
|---|---|---|
| Vinyl siding | Low upfront cost, minimal painting | Can warp or crack in temperature swings; seams allow moisture behind the panel |
| LP SmartSide (engineered wood) | Warmer wood-look appearance, easier to work with on site | Wood-based core is vulnerable if any cut edge or seam isn't sealed and maintained |
| Cedar / primed spruce | Natural, traditional look | Requires regular refinishing; rot risk climbs fast in prolonged damp conditions |
| Cemplank / Allura (other fiber cement) | Similar core material to Hardie | Different factory finish and warranty backing than what we've standardized on |
| James Hardie fiber cement | Non-combustible, dimensionally stable, factory-baked ColorPlus finish | Higher installed cost; needs correct fastening and flashing to perform as designed |
Fiber cement is dimensionally stable, which matters in a climate where materials are constantly absorbing and releasing moisture. Hardie's ColorPlus finish is baked on at the factory rather than field-painted, which removes one of the biggest long-term maintenance items — repainting — from a homeowner's list. It's also non-combustible, which is a meaningful consideration as wildfire smoke and dry-season fire risk have become a bigger part of the conversation even in western Washington.
The HZ5 Product Line: Built for This Region
James Hardie engineers its siding in climate-specific formulations, and the HZ5 line is designed for the wetter, more temperate regions of the Pacific Northwest. That means the board itself is formulated to resist moisture-related damage in exactly the kind of weather pattern Whatcom County sees most of the year — not a generic product pulled from a national catalog. We install the HZ5 line as our standard for homes in Sumas and across the rest of our service area.
Installation Is Where Siding Actually Succeeds or Fails
Fiber cement siding is only as good as the flashing, fastening, and joint details underneath it. A correctly installed lower-tier product will outperform a premium product installed poorly, every time. Our installation approach includes:
- Correct fastener placement and spacing per manufacturer specification, not shortcuts to save labor time
- Proper flashing at windows, doors, and any wall penetration to direct water outward, not behind the siding
- Rain screen or drainage gap detailing appropriate to the wall assembly
- Factory-mitered or properly caulked joints to keep cut edges sealed from moisture
- Attention to ground clearance so siding isn't sitting in a position to wick up moisture from grade
This is the kind of detail work that's easy to skip and hard to spot after the fact — until a wall starts showing problems years later. It's also where hiring a crew that specializes in one product system, rather than juggling five different materials, tends to pay off.
Beyond Siding: Roofing, Windows, and Decks
Siding is our specialty, but exteriors don't fail in isolation — a roof leak, a failed window seal, or a rotting deck ledger can undermine even a well-installed wall system. We handle all four:
Roofing
A roof in poor condition sends water down onto siding, trim, and fascia it was never meant to handle. We evaluate roof condition as part of any siding project and handle roofing work directly rather than referring it out.
Windows
Window flashing and siding installation are directly connected — poor integration at the window opening is one of the most common sources of hidden water damage in this climate. We install and integrate windows as part of a full exterior scope when that's what a project calls for.
Decks
Decks take a similar beating from year-round moisture exposure, particularly at ledger connections and any wood-to-ground contact. We build and repair decks with the same attention to water management we bring to siding work.
What Drives Cost on a Sumas Exterior Project
| Factor | Why It Matters |
|---|---|
| Home size and wall complexity | More corners, gables, and penetrations mean more flashing and labor detail |
| Existing siding removal | Tear-off and disposal of old material adds time versus a bare-wall install |
| Underlying damage | Rotten sheathing or framing found during tear-off needs repair before new siding goes on |
| Siding profile and color | Lap width, shingle-style panels, and ColorPlus color selection carry different material costs |
| Trim and accent work | Window casings, corner boards, and fascia detailing add scope beyond flat wall coverage |
| Access and site conditions | Slope, landscaping, and staging room affect labor time |
We don't publish flat per-square-foot pricing because these factors genuinely move the number from one house to the next. What we do provide is a clear, itemized estimate after actually looking at the home — not a phone quote guessed from a description.
What to Look For When Hiring an Exterior Contractor Here
Whatcom County has plenty of contractors who'll do siding as one of several trades they dabble in. For a climate this demanding, that's a real risk. A short checklist worth using when you're vetting anyone for exterior work in Sumas or the surrounding area:
- Are they licensed and insured in Washington, and will they show you proof without being asked twice?
- Do they specialize in the specific product they're proposing, or is it one of many they carry?
- Will they explain their flashing and water-management approach in plain terms, not just talk about the siding brand?
- Do they inspect for underlying rot or damage before quoting, rather than assuming the wall is sound?
- Is the warranty backed by both the manufacturer and the installer, with the installation labor covered too?
- Can they point to a consistent, local track record rather than a rotating crew from out of the area?
A Local Crew for Border-Country Homes
Sumas is a quieter corner of Whatcom County, and it doesn't always get the same attention from contractors based farther south or west. We treat it as part of our regular service area, not an add-on trip. That means the same crew, the same James Hardie standard, and the same installation detail we bring to every job in the county — for a home that's dealing with the same wind, rain, and moss pressure as the rest of the region, right down to the border.
If your siding, roof, windows, or deck are showing signs of wear — or you're planning ahead before they do — we're happy to take a look and put together a straightforward, no-pressure estimate. There's no cost or obligation to have us out.