Bellingham Homeowners in Bellingham ask us about LP SmartSide often enough that we think it deserves a straight answer instead of a sales pitch. It's a legitimate engineered wood siding product with real advantages, and plenty of contractors install it well. We don't. This page explains what SmartSide does right, where it runs into trouble in a Whatcom County climate, and why we standardized on James Hardie fiber cement instead.
What LP SmartSide Actually Is
LP SmartSide is an engineered wood product — strand board or composite substrate treated with resins, zinc borate for insect and fungal resistance, and a factory-applied primer or finish. It's manufactured to look like traditional wood lap siding, board-and-batten, or shingle patterns, at a lower material cost than real cedar and a lower installed cost than most fiber cement. For builders working to a tight budget, that combination is genuinely appealing, and the panels are lighter and easier to cut and nail than fiber cement, which can speed up installation labor.
LP has improved the product over the past two decades. Current SmartSide products carry a manufacturer warranty and are treated for moisture resistance at the core. On paper, it competes directly with fiber cement siding. In practice, the two products behave very differently once they're on a wall in a marine climate for fifteen or twenty years.
The Core Issue: It's Still Wood
Strand board and composite wood siding is, at its core, wood fiber held together with adhesive resin. Wood fiber absorbs moisture. LP's treatments slow that process and protect against rot and insects better than untreated wood, but they don't change the underlying physics — if the factory seal is compromised at a cut edge, a fastener hole, a butt joint, or a scratch, and moisture gets in and stays in, the material can swell, delaminate, or soften at that point. That's a slower, more forgiving failure mode than it used to be with older OSB-based sidings, but it's not eliminated.
Fiber cement doesn't have that vulnerability. It's cement, sand, and cellulose fiber — inorganic at its core. It doesn't swell when wet and it doesn't feed rot or insects because there's no organic food source for them to work with. That's the fundamental difference we keep coming back to when we're standing on a ladder deciding what to put on someone's house for the next 30-plus years.
Why This Matters More in Bellingham
Whatcom County isn't a dry climate. Bellingham sees driving rain off the Strait of Georgia and Bellingham Bay, salt-laden air along the waterfront and up into the county, and a long moss and lichen season that keeps north-facing walls damp for months at a stretch. Any siding product installed here spends more of the year wet than a comparable house in eastern Washington. That doesn't make engineered wood siding a bad choice everywhere — it makes it a product whose weak points get more exercise here than in a drier region.
Where SmartSide Installation Gets Sensitive
SmartSide's field performance leans heavily on installation quality. The manufacturer's instructions are specific about cut-edge sealing, minimum ground clearance, fastener placement, and caulking at joints and penetrations — and for good reason. Every cut edge on a job site is an unsealed edge until the crew treats it, and every missed detail is a future entry point for water. A crew in a hurry, or one that isn't trained specifically on this product's requirements, can install SmartSide in a way that looks fine on day one and causes problems five years later.
- Factory-primed edges are sealed; field cuts are not, and every cut must be sealed with the manufacturer-specified primer before installation
- Minimum clearance from grade, decks, roofing, and hardscaping has to be maintained to keep splash-back moisture off the panel
- Butt joints and panel-to-trim gaps need proper caulking and flashing, not just a bead of sealant
- Fasteners have to be placed and driven correctly — overdriven nails crush the material and break the seal around the fastener
- Any moss, algae, or debris buildup at panel laps should be cleaned off regularly so moisture doesn't sit against the surface
None of this is impossible to get right. It's just that the margin for error is smaller than with fiber cement, and in a wet coastal climate, installation mistakes get found out faster.
Moss, Algae, and Long-Term Appearance
Bellingham's moss season is long — shaded, north-facing walls and anything near overhanging trees stay damp for much of the fall through spring. Any siding surface will accumulate some biological growth here, but the concern with engineered wood is what's happening underneath the surface, not just on top of it. Moss and algae hold moisture against the panel face longer than a bare surface would, and on a wood-based product that's exactly the condition you want to minimize. Fiber cement handles the same growth cosmetically — a wash removes it — without the same underlying material risk.
Maintenance and Repainting
SmartSide requires ongoing maintenance to hold up to its warranty terms and to perform as designed: periodic caulk inspection, cleaning, and repainting on a schedule the manufacturer specifies, along with prompt attention to any impact damage or scratches that expose raw material. Skipping or delaying that maintenance is one of the more common ways engineered wood siding runs into trouble, because the areas most likely to fail are also the least visible from the ground — the bottom starter course, under window sills, around penetrations.
Hardie's ColorPlus factory finish is baked on and warranted separately from the substrate, with a much longer repainting interval expected under normal conditions. That doesn't mean zero maintenance — no siding is maintenance-free — but the maintenance burden and the consequences of deferring it are meaningfully different between the two products.
Fire and Impact Considerations
Fiber cement is non-combustible; it doesn't contribute fuel to a fire the way wood-based products do, which matters more each year given Pacific Northwest wildfire seasons and defensible-space conversations even on the wetter west side of the Cascades. SmartSide is treated but still an engineered wood product for fire classification purposes. Fiber cement also holds up better against hail, wind-driven debris, and everyday impact — it doesn't dent or splinter the way strand board can when it's struck.
Cost Comparison
| Factor | LP SmartSide | James Hardie Fiber Cement |
|---|---|---|
| Material cost | Lower | Moderate to higher |
| Installed labor | Somewhat faster to install | Slower, more cut-edge and fastener discipline required |
| Moisture tolerance | Treated but organic substrate | Inorganic, does not swell or rot |
| Fire classification | Combustible (engineered wood) | Non-combustible |
| Repainting interval | Shorter, manufacturer-scheduled | Longer with ColorPlus factory finish |
| Warranty structure | Manufacturer warranty, maintenance-dependent | Strong transferable warranty |
| Long-term maintenance burden | Higher — caulk, cut edges, moisture checks | Lower — periodic wash and inspection |
Why We Standardized on James Hardie
We install one siding system, and we did that on purpose. James Hardie fiber cement gives us a non-combustible, moisture-stable product with a factory-applied ColorPlus finish, climate-engineered HZ product lines suited to the Pacific Northwest, and a strong transferable warranty that isn't as dependent on a homeowner catching every maintenance item on schedule. When it's installed correctly — proper clearances, flashing, and fastening, which we do the same way on every job because it's the only system we run — it holds up to Bellingham's rain, salt air, and moss season with less drama over the life of the siding than an engineered wood product asks for.
That's not a knock on everyone who chooses or installs SmartSide. It's a reasonable product for a lot of situations. It's just not the trade-off we're willing to make on our own installs, given what this climate does to a wall over three decades.
Questions to Ask Before You Choose a Siding Product
- What is the substrate made of, and how does it behave when moisture gets past the surface finish?
- What does the manufacturer's warranty actually require of you to stay valid — and how easy is it to document that you met those terms years later?
- What's the realistic repainting or recoating interval, and what does that cost over 20 years?
- How forgiving is the installation process, and how experienced is your crew specifically with this product?
- How does the product perform in a wet, coastal, moss-prone climate — not just a national average?
If you're weighing siding options for a home in Bellingham or elsewhere in Whatcom County, we're happy to walk your specific house with you and talk through what we'd actually recommend and why. Reach out for a free, no-pressure estimate using the form below.