Semiahmoo Two Different Materials, One Big Decision
If you're replacing siding in Semiahmoo, you've probably run into two products that dominate the higher end of the market: James Hardie fiber cement and LP SmartSide engineered wood. Both are marketed as upgrades over vinyl, both look good on a spec sheet, and both show up on contractor bids around Whatcom County. But they are fundamentally different materials with different long-term behavior, and that difference matters more here than in a lot of the country.
This page lays out what each product actually is, how they perform against salt air and driving rain off Semiahmoo Bay, and why our crews install James Hardie exclusively.
What Each Product Is Made Of
James Hardie siding is fiber cement: a mix of Portland cement, sand, and cellulose fibers, cured into rigid boards and panels. It's non-combustible and dimensionally stable, meaning it doesn't expand and contract with moisture the way wood-based products do.
LP SmartSide is engineered wood — wood strands or wafers bonded with resins, treated with a zinc borate preservative, and finished with a wax coating. It's a real improvement over old-school masonite siding from the 1990s, and LP has put real engineering into the treatment process. But it's still wood at its core, which means it can absorb moisture, swell, and eventually break down at cut edges and fastener points if the water-resistant barrier is ever compromised.
Why This Matters in Semiahmoo
Semiahmoo sits right on the water, and that changes the math on siding materials. Homes here deal with three things most inland Whatcom County properties don't face at the same intensity:
- Salt air — airborne salt accelerates corrosion on fasteners and can work into any exposed seam or cut edge over time.
- Driving rain — wind-driven rain off the Strait pushes water sideways into siding, not just down, stressing joints and horizontal laps harder than a typical inland rain event.
- A long moss and mildew season — the Pacific Northwest's wet, mild winters mean north-facing and shaded walls stay damp for months, giving moss and mildew a long runway to establish themselves.
Fiber cement doesn't feed mold, moss, or mildew the way wood-based products can, and it doesn't swell when it takes on moisture at a cut edge. Engineered wood siding can still perform well in this climate when it's installed correctly and every cut edge is sealed per the manufacturer's spec — but that installation discipline has to hold up for decades, on every single edge, forever. That's a bigger ask on a bayfront property than on a home two hours inland.
Side-by-Side Comparison
| Factor | James Hardie (fiber cement) | LP SmartSide (engineered wood) |
|---|---|---|
| Core material | Cement, sand, cellulose fiber | Wood strands with resin binder |
| Combustibility | Non-combustible | Combustible (wood-based) |
| Moisture behavior | Dimensionally stable; does not swell | Can swell/degrade if cut edges aren't sealed |
| Moss/mildew resistance | Inorganic surface resists growth | Treated, but organic core is more vulnerable long-term |
| Factory finish option | ColorPlus baked-on finish, multi-year warranty | Primed or factory-finished options available |
| Installation sensitivity | Moderate — standard fiber cement practices | High — every cut edge must be field-sealed correctly |
What LP SmartSide Gets Right
To be fair to the product: LP SmartSide is lighter than fiber cement, which can make it faster to install, and it takes fasteners and cuts more like traditional wood siding, which some crews find familiar. For inland homes without heavy coastal exposure, and with a contractor committed to sealing every cut edge to spec, it can be a reasonable siding choice. We're not here to tell you it's a bad product — it isn't.
Why We Standardized on James Hardie
We made a decision as a company to install James Hardie exclusively, and a big part of that decision is the environment we work in. Semiahmoo and the surrounding Whatcom County waterfront push siding harder than most of the country — salt air, sideways rain, and a moss season that doesn't really end. Fiber cement's non-combustible, moisture-stable core removes an entire category of long-term risk that engineered wood carries, no matter how well the initial install goes.
James Hardie also backs its ColorPlus factory-finished products with a strong, transferable warranty, and the HZ5 product line is specifically engineered for the Pacific Northwest's wet climate — thicker moisture management, built for exactly the conditions Semiahmoo homes see year-round. When we install it to Hardie's spec — correct clearances, proper flashing, factory-finished cuts wherever possible — we're putting a material on your home that's built for this coastline, not just tolerant of it.
Making the Right Call for Your Home
The right siding choice depends on your home's exposure, your budget, and how long you plan to own the property. We're happy to walk your specific site — how much direct salt spray it gets, which walls stay shaded and damp, what your current siding is telling us about past moisture problems — and give you a straight answer about what will hold up.
If you'd like a free, no-pressure estimate and a look at how James Hardie siding would perform on your specific property, reach out and we'll come take a look.