Bellingham Exterior What LP SmartSide Actually Is
LP SmartSide is an engineered wood siding product — strand-based wood fiber that's treated with zinc borate for insect and rot resistance, then coated with resin and wax and finished with a primer or factory coating. It's manufactured by Louisiana-Pacific, it's been on the market for decades, and it has real advantages: it's lighter than fiber cement, easier on saw blades, and less likely to crack if a ladder or a stray baseball catches it wrong. For interior trim carpenters and DIY-friendly remodels, it has a following for good reason.
We're not here to tell Bellingham homeowners that LP SmartSide is a bad product. It's a wood-based product doing a wood-based product's job. Our issue isn't with LP as a company — it's that after years of installing exterior siding in Whatcom County, we made a call to install only James Hardie fiber cement, and we think homeowners deserve to know why before they sign a contract with anyone.
The Core Problem: It's Still Wood
Underneath the resin coating and zinc borate treatment, LP SmartSide is still an engineered wood product. Wood — even engineered, treated wood — swells and shrinks with moisture, and it's dimensionally reactive in a way that fiber cement simply isn't. That's not a manufacturing defect; it's the nature of the material. The question for a homeowner isn't "is this good engineered wood," it's "does engineered wood make sense for this specific house, in this specific climate."
Where This Shows Up in the Field
The most common issue we see with wood-based siding products in this region isn't catastrophic failure — it's slow edge swelling at cut ends, seams, and butt joints where moisture finds its way in over years of exposure. Once the wood fibers at an edge absorb water and swell, the factory finish can crack at that seam, and once the finish cracks, moisture gets in faster on the next cycle. It's a gradual problem, which is exactly why it's easy to underestimate when you're comparing products on a showroom sample instead of on a fifteen-year-old house.
Why Bellingham's Climate Makes This Worse
Whatcom County isn't the harshest climate in the country, but it stacks several moisture stressors on top of each other in a way that matters for wood-based siding. We get salt air off Bellingham Bay and the Strait of Georgia, which accelerates corrosion and finish breakdown on anything with exposed fasteners or seams. We get driving rain that comes in sideways off Pacific storm systems, which pushes water into laps and joints that would stay dry in a calmer climate. And we get a long moss and algae season — mild, damp winters and shoulder seasons that keep exterior surfaces wet for extended stretches, which is exactly the condition organic growth needs to take hold on a wood-fiber substrate.
None of these three factors alone would be disqualifying. Together, on a material that's dimensionally sensitive to moisture in the first place, they add up to a maintenance burden we don't think most homeowners are signing up for when they buy siding they expect to last 30-plus years with minimal upkeep.
Moss and Algae Specifically
Engineered wood siding with a painted or primed finish gives moss and algae spores something to grip that a properly finished fiber cement board doesn't offer as readily. In a marine climate with our cloud cover and rainfall pattern, north-facing walls and shaded elevations near mature trees are especially prone to green and black staining within a few years of installation — meaning periodic washing (and sometimes re-coating) becomes part of the ownership experience, not an occasional chore.
Installation Sensitivity — Why the Details Matter So Much
LP SmartSide's manufacturer publishes detailed installation specs for a reason: gaps at butt joints, proper caulking at seams, correct fastener placement, and field-cutting all edges with sealant are not optional steps — they're the difference between a siding job that performs and one that swells and fails early. That's true of most siding products to some degree, but wood-based siding has less margin for error than fiber cement, because once moisture gets past an unsealed cut edge, the clock starts on that board.
We install a lot of siding, and we've seen firsthand how much installation quality varies across contractors — not just in Bellingham, but everywhere. A perfectly installed engineered wood product can perform well for a long time. The problem is that "perfectly installed" requires every field cut to be sealed, every seam to be caulked correctly, and every fastener to be placed within spec, on every wall, in every weather condition the crew works in. We'd rather standardize on a product where a normal, careful installation — not a flawless one — gets you a durable result.
The Warranty Fine Print
LP SmartSide's warranty is generally solid on paper, but like most siding warranties, it has installation and maintenance conditions attached — and moisture-related failures are exactly the kind of claim where documentation of the installation and maintenance history matters most. If a homeowner doesn't keep up with recommended re-coating schedules or the original installer didn't follow spec on caulking and clearances, that history can complicate a claim years down the road, long after the original installer may be hard to track down or the receipts are gone.
We're not saying LP's warranty is designed to be denied. We're saying that any warranty with maintenance and installation contingencies puts real responsibility on the homeowner to keep records and stay current on upkeep for decades. That's a legitimate ownership model — it's just not the one we want to sell people on.
Maintenance Reality: Side by Side
| Factor | LP SmartSide (engineered wood) | James Hardie (fiber cement) |
|---|---|---|
| Core material | Wood strand composite, resin/wax treated | Cement, sand, and cellulose fiber |
| Moisture behavior | Dimensionally reactive; edge swelling risk if seams fail | Non-organic; does not swell, rot, or feed fungal growth |
| Fire rating | Combustible (treated for flame spread, still wood-based) | Non-combustible |
| Finish | Primed or factory-coated; often needs field painting/re-coating over time | ColorPlus factory finish, baked-on, engineered for UV and moisture |
| Typical recoat interval | Often 7-10 years depending on exposure | ColorPlus finish commonly holds 15+ years before repaint is needed |
| Moss/algae susceptibility in wet marine climates | Moderate to higher, especially on shaded elevations | Lower; smoother factory finish sheds growth more easily |
| Insect/rot resistance | Treated with zinc borate; resistance is chemical, not structural | Not a food source for insects or fungus |
Why We Standardized on James Hardie Instead
James Hardie fiber cement isn't wood, so it doesn't share wood's core vulnerability — it doesn't swell at cut edges the same way, it doesn't rot, and it's not a food source for insects or fungus. It's non-combustible, which matters to more homeowners every year given wildfire smoke seasons across the Pacific Northwest, even in a wetter market like ours. Hardie's HZ5 product line is engineered specifically for climate zones that deal with sustained moisture exposure, which describes Whatcom County about as well as anywhere in the state.
The ColorPlus factory finish is baked on under controlled conditions rather than applied on site or left to a field crew's paint schedule, and it's backed by a warranty structure that doesn't hinge on a homeowner's re-coating diligence the way wood-based finishes often do. We also like that Hardie boards install with a consistent, well-documented process across every product line, which means the installation quality that protects a warranty claim is less dependent on any one crew's individual caulking habits on any given day.
None of this means Hardie is maintenance-free — no exterior siding is. It still needs to be caulked, flashed, and installed to spec, and it still benefits from periodic washing in a mossy climate like ours. But it starts from a material baseline that doesn't fight the Bellingham climate the way an organic, moisture-reactive substrate does.
What We Do Instead of Engineered Wood
When a homeowner asks us about LP SmartSide, Cemplank, Allura, or other alternatives, we walk them through the same trade-offs laid out here, then show them the specific James Hardie HZ product line, color, and profile that fits their home and their budget. We'd rather have that conversation up front than install a product we're not confident will hold up through a few decades of Bellingham winters.
Questions to Ask Before You Commit to Any Siding Product
- What is the manufacturer's specified installation process, and will the crew installing it follow it exactly — caulking, fastener spacing, clearances, all of it?
- Does the warranty require ongoing maintenance documentation (re-coating, cleaning), and who's responsible for keeping those records?
- How does this material perform specifically in a marine, high-rainfall, moss-prone climate — not just in the manufacturer's general marketing?
- Is the product non-combustible, and does that matter for your insurance or personal risk tolerance?
- What's the realistic re-coating or repainting interval, and what does that cost over 20 years, not just at installation?
- Has the contractor actually installed this specific product in this specific region, or are they learning on your house?
Our Honest Bottom Line
LP SmartSide is a legitimate product that works fine in a lot of climates and on a lot of homes when it's installed exactly to spec and maintained on schedule. Our decision to install only James Hardie isn't a claim that engineered wood siding is defective — it's a professional judgment, built from years of siding work in Whatcom County's specific mix of salt air, driving rain, and moss season, that fiber cement gives our customers a better long-term outcome with less ongoing risk and upkeep. We'd rather stand behind one product we trust completely than offer several we'd have to caveat.
If you're weighing siding options for a home in Bellingham or anywhere in Whatcom County, we're happy to walk your specific house, talk through what we're seeing on the exterior now, and put together a free, no-pressure estimate for a James Hardie install — no obligation, no pressure, just a straight answer about what we'd recommend and why.