Ferndale Siding Custer's Siding Problem Isn't Like Everyone Else's
Custer sits in that stretch of northern Whatcom County where three things converge on a house at once: salt-laden air rolling in off the Strait of Georgia and Birch Bay, driving rain that comes in sideways during winter frontal systems, and a moss season that, realistically, runs eight or nine months out of the year. Any one of those is manageable. All three hitting the same wall assembly, year after year, is what actually wears siding out around here — not one dramatic storm, but the slow accumulation of moisture cycles, salt exposure, and organic growth that most siding products were never engineered to shrug off.
We install James Hardie fiber cement siding specifically because it holds up to that combination better than the alternatives we've evaluated. This page is about what that looks like on a Custer home in particular — not a generic rundown of fiber cement siding, but what the climate here actually demands and how we build for it.
What Salt Air Actually Does to a House
Salt air doesn't rot siding the way trapped moisture does — it works differently, and it's easy to underestimate if you haven't seen it up close on a coastal Whatcom County property. Airborne salt settles on exterior surfaces and accelerates corrosion on anything metal: fasteners, flashing, trim screws, even factory-finish hardware if it's the wrong grade. It also holds moisture against a surface longer than plain rainwater does, because salt is hygroscopic — it pulls humidity out of the air and keeps a film of dampness sitting on the siding surface even between rain events.
For a wood-based or wood-fiber product, that constant low-grade dampness is exactly the condition that breeds rot and delamination. For vinyl, salt exposure combined with UV tends to show up as chalking and brittleness years before it should. Fiber cement doesn't have organic material for the salt to feed on, and it doesn't degrade from surface moisture the way wood-based products do — but the installation details around it, especially fasteners and flashing, still have to be salt-appropriate or they become the weak point instead.
Why This Matters More in Custer Than Inland Whatcom County
Homes further inland — say, out toward Lynden or the Nooksack valley — deal with plenty of rain but not the same steady salt load. Custer's proximity to Birch Bay and the Strait puts it in a different exposure category, closer to what you'd plan for on a straight waterfront property. We treat Custer jobs with that in mind rather than defaulting to an inland spec.
Driving Rain and the Wall Assembly Behind the Siding
Whatcom County's winter storms don't just drop rain — they push it. Wind-driven rain finds every gap, lap, and penetration in a siding system and tries to get behind it. Fiber cement itself is dimensionally stable and doesn't swell or cup the way some wood-based sidings do when it gets wet, but no siding product is actually waterproof on its own. The water-resistive barrier behind the panels, the flashing at windows and doors, and the way laps and joints are detailed all matter as much as the siding material itself.
A correct installation in a driving-rain climate like Custer's means:
- Proper weather-resistive barrier installed and lapped correctly (shingle-fashion, top over bottom) behind the siding
- Flashing integrated at every window, door, and roof-to-wall transition — not caulk substituting for flashing
- Minimum required lap and gap dimensions held consistently, not eyeballed
- Kick-out flashing at roof-wall intersections so runoff is directed away from the wall rather than behind it
- Butt joints properly caulked or, where possible, backed with flashing rather than relying on sealant alone
Skip any of these and the siding material grade stops mattering — water gets behind a wall assembly the same way whether the face material is premium or bargain.
Custer's Long Moss Season
Moss needs shade, moisture, and a surface it can grip. Custer's tree cover, marine humidity, and mild winter temperatures give it all three for most of the year. On siding, moss and algae growth is mostly a north- and west-facing problem, and it tends to concentrate wherever a wall stays damp longest — under eaves with poor drip edges, behind landscaping that's grown up against the house, or on any surface with a rough enough texture to hold spores and moisture.
James Hardie's factory-applied ColorPlus finish is smoother and more consistently sealed than field-applied paint, which gives moss and algae less to grab onto compared to a porous or unevenly coated surface. It's not a moss-proof coating — nothing exterior-grade truly is in this climate — but it's a meaningfully harder surface for organic growth to establish on, and it holds up to the occasional gentle wash without the coating failing the way a thin field-applied paint job can after a few cleanings.
Why We Only Install James Hardie Here
We don't install LP SmartSide, vinyl, Cemplank, Allura, or bare cedar or primed spruce siding, and Custer's climate is a big part of why. Wood-strand products like LP SmartSide depend on an intact factory coating to keep moisture out of an engineered wood substrate — once that coating is compromised at a cut edge, a fastener hole, or a weathered spot, the substrate underneath is vulnerable in exactly the damp, salt-humid conditions Custer sees most of the year. Vinyl is inexpensive and low-maintenance in mild climates, but it isn't rigid, and driving rain plus wind can work it loose at the laps over time; it also doesn't take paint if a homeowner ever wants to change the color. Bare cedar and primed spruce are beautiful but need real maintenance discipline — refinishing on a schedule, vigilant caulk and flashing upkeep — to survive this much annual moisture without checking, cupping, or rot.
James Hardie fiber cement is cement, sand, and cellulose fiber — it doesn't have the organic vulnerability of wood-based sidings, it's non-combustible, and it's engineered in regional formulations (the HZ5 product line is built for this kind of climate) specifically to handle moisture cycling. That's the honest reason we standardized on one product instead of offering several: we'd rather install the one we're confident holding up on a Custer wall for decades than offer a menu of products with different long-term risk profiles.
Comparing What Custer Homes Actually Face
| Climate Factor | What It Does to Siding | How Hardie Fiber Cement Responds |
|---|---|---|
| Salt air (Strait / Birch Bay proximity) | Corrodes fasteners and metal trim; keeps surfaces persistently damp | Non-organic substrate resists degradation; we spec corrosion-resistant fasteners and flashing |
| Driving rain | Pushes water behind laps, joints, and penetrations | Dimensionally stable panel paired with correct WRB, flashing, and lap detailing |
| Long moss/algae season | Organic growth on shaded, damp wall surfaces | Smooth factory ColorPlus finish resists spore adhesion; tolerates gentle washing |
| Freeze-thaw winter swings | Cracks and stresses porous or moisture-absorbing materials | Engineered density resists cracking from moisture-freeze cycling |
What Our Process Looks Like on a Custer Job
Assessment
We start by looking at the whole wall system, not just the visible siding — how the existing WRB and flashing are performing, where moss and staining are concentrated (that tells us where moisture is lingering), and which elevations take the worst of the wind-driven rain given the home's orientation and tree cover.
Prep and Correction
Any deficient flashing, damaged sheathing, or missing kick-out flashing gets corrected before new siding goes on. Installing quality siding over a compromised wall assembly just hides the problem for a while — it doesn't fix it.
Installation to Spec
We follow James Hardie's published installation instructions on fastener spacing, clearances above grade, gapping, and caulking — this is also what keeps the manufacturer's warranty valid, since improper installation is the most common reason fiber cement warranty claims get denied industry-wide.
Final Walkthrough
We check every penetration, corner, and transition before calling a job finished, because on a site like Custer, the failure points that show up in year three or four are almost always installation details, not the material itself.
Why a Crew That Already Works Custer Matters
Building code minimums and manufacturer installation guides are written for a wide range of climates. A crew that's installed siding across drier or less exposed parts of Whatcom County can follow every instruction to the letter and still under-build for what Custer actually throws at a wall. Knowing to treat this area more like a coastal spec than an inland one — heavier attention to fastener corrosion resistance, more conservative flashing details, awareness of which elevations catch the worst of the wind-driven rain — comes from having done the work here before, not just from reading a manual.
Maintenance Realities for Custer Homeowners
Fiber cement is genuinely low-maintenance compared to wood, but "low-maintenance" isn't "no-maintenance" in this climate. A realistic annual routine:
- Rinse siding gently once or twice a year, focusing on north- and west-facing walls where moss tends to establish first
- Keep landscaping and tree branches pulled back from siding so walls can dry out between rain events
- Check and clear gutters before the fall rains start, since overflow is a common source of localized water damage at wall corners
- Inspect caulking at trim and penetrations every year or two and re-caulk where it's cracked or pulled away
- Watch for any staining or discoloration that could indicate a flashing or gutter issue behind the surface, not just a cosmetic one
What Drives Cost on a Custer Project
| Factor | Why It Matters Here |
|---|---|
| Existing wall condition | Homes with moisture-damaged sheathing or failed flashing need repair before new siding goes on |
| Home size and elevation exposure | Walls facing prevailing wind and rain often need extra flashing and detailing attention |
| Product line and profile | Lap width, shingle-style panels, and trim choices affect material and labor |
| Tear-off vs. re-side | Removing existing siding down to sheathing costs more but lets us fully correct the WRB and flashing |
| Color and finish | Factory ColorPlus finishing adds cost over field-painted options but removes a maintenance burden long-term |
We won't quote a number without seeing the home, but these are the factors that move a Custer estimate up or down, and we'll walk through each one with you honestly during the assessment.
Ready to Talk About Your Home
If your Custer home's siding is showing moss buildup, staining, or signs of moisture behind the walls, it's worth having someone look at the whole picture — not just the surface. We'll walk the property, tell you honestly what we see, and explain what a correct fix looks like. Reach out below for a free, no-pressure estimate.