Lynden Siding Two Engineered Sidings, One Local Climate to Answer To
If you're replacing siding in Lynden or anywhere else in Whatcom County, you've probably narrowed your search to two engineered products: James Hardie fiber cement and LP SmartSide, an engineered wood siding. Both are a step up from old-school vinyl or unfinished wood. Both are backed by real manufacturers with real warranties. But they are not the same material, and the difference matters more here than it would in a dry climate. Lynden sits in a stretch of the Pacific Northwest that gets a long, wet shoulder season, persistent moss growth on shaded and north-facing walls, and salt-laden air rolling in off the Sound on windy days. That combination is a genuine stress test for any exterior product, and it's the reason we only install one of these two.
What LP SmartSide Actually Is
LP SmartSide is an engineered wood product — strand-based substrate treated with resins and zinc borate for insect and fungal resistance, then coated with a factory finish. It's lighter than fiber cement, easier to cut and nail with standard wood tools, and it holds up better than raw plywood or hardboard siding did in decades past. For homeowners on a budget who still want a wood look, it's a legitimate option, and we're not going to pretend otherwise.
The catch is that it's still fundamentally a wood product. Wood swells, contracts, and — if moisture gets past the finish at a cut edge, a fastener hole, or a failed caulk joint — it can begin to soften and delaminate. LP has improved the formulation over the years and the treated substrate resists rot far better than untreated lumber, but "resists" is not "immune." In a climate where a wall can stay damp for days at a stretch during our fall and winter rain, and where moss holds moisture directly against the siding surface for months if it isn't cleaned off, every seam, joint, and cut edge becomes a place that needs to be sealed correctly and stay sealed. That's a maintenance commitment, not a one-time installation task.
What James Hardie Fiber Cement Is
James Hardie siding is cement, sand, and cellulose fiber, cured into a dense, non-combustible board. It doesn't absorb water the way wood does, it doesn't provide food for insects, and it doesn't feed mold and mildew the way an organic substrate can. Hardie's HZ5 product line is specifically engineered for climates with extended moisture exposure and freeze-thaw cycling — which describes a Whatcom County winter reasonably well. The ColorPlus factory finish is baked on under controlled conditions and backed by its own finish warranty, separate from the substrate's own coverage, so you're not relying on a field-applied paint job to be your only line of defense against the weather.
None of that makes Hardie maintenance-free. It still needs to be caulked correctly at joints, painted or color-matched when touch-up is needed, and kept clear of soil and mulch contact. But the failure modes are different in kind — you're managing a caulk joint or a coating, not managing whether the core material itself is absorbing water.
Side-by-Side Basics
| Factor | LP SmartSide | James Hardie |
|---|---|---|
| Core material | Engineered strand wood | Fiber cement |
| Moisture behavior | Resistant, but wood-based | Non-organic, does not rot |
| Fire rating | Combustible | Non-combustible |
| Install sensitivity | Cut edges/joints need consistent sealing | Requires trained crew, correct fastening and clearances |
| Finish | Factory-primed or coated | Factory-baked ColorPlus finish available |
Why Moss Season and Salt Air Change the Calculation
A lot of siding comparisons get written for a generic climate. Here, the details matter. Whatcom County's moss doesn't just sit on roofs — it colonizes the shaded lower courses of siding on homes near tree lines, and it holds water against the wall surface long after a rain has stopped. On an organic substrate, that's sustained moisture contact exactly where you don't want it. Add the corrosive effect of salt-laden air on fasteners and finishes near the water, plus driving rain that pushes moisture sideways into joints and butt seams, and you've got three separate stressors working on the same product at the same time. Fiber cement isn't bothered by any of the three the way an organic material can be.
Why We Standardized on Hardie
We install James Hardie exclusively — not LP SmartSide, not vinyl, not cedar or primed spruce. That's a deliberate professional standard, not a sales position. When we're the ones whose workmanship warranty is tied to how the siding performs over the next 20-plus years in this specific climate, we want a substrate that doesn't depend on a perfect, permanent seal at every cut and joint to avoid moisture problems. Hardie's non-combustible core, its climate-engineered HZ5 line, and its factory finish give us a system we can install to spec and stand behind, in weather that genuinely tests exterior materials.
If you're weighing your options for an upcoming project, we're happy to walk your home, point out where moisture and moss are already a factor, and give you a straight answer on what it would take to do the job right. Reach out for a free, no-pressure estimate.