Birch Bay Exterior Exterior Contracting for Lynden Homes
Lynden sits inland from Birch Bay, tucked into the Nooksack Valley near the Canadian border, but it shares the same Whatcom County weather system that soaks the whole northwest corner of the state. Birch Bay Exterior Co has built a business around that weather — siding, roofing, windows, and decks that are chosen and installed specifically for how wet this part of Washington stays for most of the year. We drive out to Lynden regularly, and we've seen firsthand what the local climate does to homes that were finished with the wrong materials or the wrong installation details.
This page covers what Lynden homeowners should know about maintaining and upgrading their home's exterior, and how our crew approaches the work differently than a contractor who splits time between climates that don't get anywhere near this much rain.
What the Whatcom County Climate Does to a House
Driving Rain and Standing Moisture
Lynden gets a long, wet season that stretches from fall through spring, with rain that often comes in sideways on windy days rather than falling straight down. That matters more than people think — driving rain finds its way behind loose trim, into unsealed window flashing, and under siding laps that weren't installed tight. A material or installation method that works fine in a drier climate can fail here simply because it wasn't built to shed water moving horizontally, not just vertically.
Moss and Algae
Whatcom County's moss season is long, and Lynden is no exception. Roofs, siding, and anything shaded by trees or a neighboring structure can stay damp for days at a stretch, which is exactly the environment moss and algae need to take hold. Once moss establishes on a roof or siding surface, it holds moisture against the material longer, which accelerates whatever deterioration was already starting.
Salt-Influenced Air and Temperature Swings
Lynden doesn't sit directly on the water the way Birch Bay does, so it doesn't take the same direct salt spray, but the broader marine air pattern off the Salish Sea still moves through the valley, keeping humidity high even on days without active rainfall. Add in the freeze-thaw swings of a Whatcom County winter, and exterior materials here are working through constant expansion, contraction, and dampness cycles year-round.
Siding in Lynden: Why We Only Install James Hardie
Birch Bay Exterior Co installs one siding product: James Hardie fiber cement. We don't offer LP SmartSide, vinyl, Cemplank, Allura, primed spruce, or cedar, and that's a deliberate standard, not a limitation of what we know how to install.
What We Ruled Out and Why
Vinyl siding is affordable and low-maintenance in the sense that it doesn't need painting, but it expands and contracts significantly with temperature swings, and in a climate with this much sustained moisture, seams and J-channels become long-term entry points for water if they're not detailed perfectly — and stay that way for the life of the product. Wood products like cedar and primed spruce look excellent when new, but they need consistent recoating and caulking to hold up against Whatcom County's rain, and a missed maintenance cycle here shows up fast as swelling, checking, or rot. Engineered wood products like LP SmartSide perform reasonably well when installed and maintained to spec, but they still rely on a wood-based substrate, which means moisture management at every seam and cut edge is non-negotiable in a climate this wet.
Why Hardie Is What We Put on Homes
James Hardie fiber cement doesn't swell, rot, or support moss growth the way wood-based products can, and it's non-combustible, which matters given Whatcom County's dry-season wildfire smoke and risk. The ColorPlus factory finish is baked on under controlled conditions rather than field-painted, which gives a more consistent, longer-lasting finish than a job-site paint job exposed to rain during cure. Hardie's HZ5 product line is engineered specifically for climates with heavy moisture exposure, which is exactly the profile Lynden fits. The transferable warranty also gives homeowners real protection if they sell the house before the siding's functional life is over.
Hardie Product Lines We Install
| Product | Best Use | Notable Feature |
|---|---|---|
| HardiePlank Lap Siding | Most Lynden homes, standard replacement or new build | Traditional lap profile, wide color range |
| HardiePanel Vertical Siding | Accent walls, gables, modern styling | Clean vertical lines, pairs well with lap siding |
| HardieShingle | Accent areas, craftsman-style detailing | Staggered or straight-edge shingle look without cedar maintenance |
| HardieTrim | Corners, fascia, window and door trim | Matches siding durability, resists moisture at high-exposure edges |
Roofing Services
Roofing is often the first thing to show wear in this climate, since it takes the most direct and constant exposure to rain and moss. We work on asphalt composition roofing for most Lynden homes, and we pay close attention to the details that matter most locally: proper underlayment for a long wet season, ice-and-water shield at valleys and eaves, and ventilation that keeps moisture from building up in the attic. A roof that's improperly ventilated in this climate will show problems from the inside out long before shingles visibly fail from the outside.
We also handle roof repair for storm damage, moss removal and treatment, and gutter and flashing work that ties directly into a roof's ability to shed water instead of holding it.
Windows That Actually Seal Out the Weather
Window failure in Lynden is rarely about the glass — it's almost always about the flashing and sealant around the frame. A window that isn't flashed correctly will let water track down behind the siding, where it can sit unnoticed for years before showing up as a stain, soft spot, or mold smell inside the wall. When we replace windows, we treat the flashing detail as seriously as the window unit itself, and we make sure new window installations tie in cleanly with Hardie siding so there's no unprotected seam at the transition.
Decks Built for This Weather
A deck in Whatcom County spends most of the year wet, which means fastener corrosion, board cupping, and slick, moss-covered surfaces are the real long-term issues, not just sun fading. We build and repair decks with attention to drainage under and around the structure, proper spacing between boards so water doesn't pool, and hardware rated to hold up against constant moisture rather than showing rust streaks within a year or two. Railings, stairs, and ledger board connections get the same scrutiny — those are the spots where water damage tends to start.
Why a Local Crew Makes a Difference
A contractor who only occasionally works this far north can miss the small details that matter in Whatcom County's climate — how tight a lap needs to be, how much ventilation a roof deck actually needs given the moss season, or where flashing tends to fail first on homes exposed to Lynden's wind patterns. We work throughout the area regularly, which means we're not guessing at how a house here will hold up in year five or ten — we're already seeing it on the homes we've worked on nearby.
What Exterior Work Typically Costs
Exact pricing depends on the size of the home, the condition of what's being replaced, and how much repair work is hiding underneath the existing exterior. In general terms, homeowners should expect siding and roofing projects to represent a meaningful investment, with cost scaling based on square footage, the number of corners and openings, and whether old material needs to be fully removed and any underlying sheathing repaired before new material goes on.
| Factor | Why It Affects Cost |
|---|---|
| Home size and wall/roof complexity | More corners, dormers, and roof lines mean more labor and material cuts |
| Condition of existing sheathing or decking | Rot or moisture damage found during tear-off adds repair costs before new material goes on |
| Product line chosen | HardiePanel, HardieShingle, and trim accents cost more than standard lap siding alone |
| Access and site conditions | Steep lots, mature landscaping, or limited driveway access affect labor time |
Choosing an Exterior Contractor in Lynden
Homeowners planning siding, roofing, window, or deck work should go in with a short list of questions and expectations. A few things worth checking before signing anything:
- Confirm the contractor is licensed and insured in Washington State, and ask to see proof rather than taking it on faith
- Ask specifically which siding products they install and why — a contractor who installs everything often isn't specializing in the details any one product needs
- Get a clear, written scope of work that includes flashing, moisture barrier, and ventilation details, not just "siding replacement"
- Ask how they handle unexpected sheathing or framing damage found during tear-off, and how that affects cost
- Check that any warranty offered is explained clearly, including what's covered by the manufacturer versus the installer
If you're weighing options for siding, roofing, windows, or decks on a Lynden home, we're glad to take a look and talk through what makes sense for your house and budget. Reach out for a free, no-pressure estimate using the form below.