Semiahmoo What LP SmartSide Actually Is
LP SmartSide is an engineered wood siding product made from strand-based wood fiber (similar in concept to OSB) that's treated with a proprietary resin and zinc-borate formula called SmartGuard, then pressed and coated with a wax-based overlay before priming. It's a real product with real engineering behind it, and it has earned a place in the market because it's lighter than fiber cement, easier to cut and nail without special blades, and generally cheaper installed. For a lot of climates and a lot of homes, it performs fine for its warranty period.
We're not writing this page to tell you the product is junk. We're writing it because after years of doing exterior work along the Semiahmoo waterfront and throughout Whatcom County, we made a standing decision as a company to install only James Hardie fiber cement, and homeowners deserve the actual reasoning, not a sales pitch.
Where LP SmartSide Genuinely Performs Well
To be fair to the product: LP SmartSide holds paint well when properly maintained, resists impact damage better than vinyl, and in drier climates with good roof overhangs, it can go decades without serious issue. It's a wood-based product, which means it machines and installs a bit like traditional lumber siding — a trade a lot of carpentry crews are comfortable with. In the right house, right overhangs, right maintenance schedule, it's a reasonable choice.
Why We Draw the Line Here in Semiahmoo
The problem isn't the product in a vacuum — it's the product against this specific stretch of coastline. Semiahmoo sits right on the water at the top of Whatcom County, which means every house here deals with a combination of conditions that stress wood-based siding harder than almost anywhere else in the state.
Salt Air and Wind-Driven Moisture
Semiahmoo's marine exposure means siding here isn't just getting rained on — it's getting salt-laden air pushed directly at exterior walls, often at an angle, off Semiahmoo Bay. That salt-laden moisture finds its way into any gap, seam, or unsealed cut edge faster than it does inland. LP SmartSide's core is still wood fiber under its coatings, and wood fiber that stays damp swells, and swelling at a seam or butt joint is where the real problems start.
Driving Rain, Not Just Rain
Whatcom County gets plenty of rain, but the driving component — rain pushed sideways by wind off the Strait — is what matters for siding. Vertical rain sheds off a wall. Driving rain gets forced up and under laps, into nail penetrations, and into any factory edge that wasn't fully sealed or field-cut without proper sealant. LP SmartSide's installation instructions are explicit about sealing every cut edge and maintaining specific clearances — miss one on a house exposed to driving rain and you've created an entry point that doesn't show up as a problem for a few years.
A Long Moss Season
North Sound winters are long, gray, and damp, and mossy growth on north-facing walls and anything under tree cover is a fact of life here, not an edge case. Moss holds moisture against a wall surface for extended periods. On fiber cement, sustained dampness against the surface is a non-issue because the material itself doesn't absorb and swell. On a wood-fiber substrate, prolonged surface dampness is exactly the condition the manufacturer's installation and maintenance guidance is trying to help you avoid — which means homes here need more vigilant upkeep than the same product would need in a drier region.
Installation Sensitivity Is the Real Issue
Almost every documented problem with engineered wood siding traces back to installation details, not the product itself sitting in a warehouse. Edge sealing, caulking at every field cut, proper flashing above windows and doors, correct nailing height, and keeping the bottom edge off the ground and away from splash-back — these aren't optional suggestions, they're the conditions the warranty is built on. In a forgiving climate, a missed detail might never surface. On a house facing Semiahmoo Bay, a missed detail becomes the spot where water gets in.
We install a lot of siding, and we've seen how much installation quality varies from crew to crew and from job to job — even good crews have an off day. A material that's genuinely tolerant of small installation misses gives homeowners more real-world margin than one that requires everything done exactly right, every time, forever.
Maintenance Burden Over Time
LP SmartSide needs to be repainted or recoated on a maintenance cycle to keep its protective layer intact — the factory primer isn't the final finish coat. That's a real ongoing cost and a real ongoing task for the homeowner: inspecting caulk lines, touching up paint, watching for any spot where the finish has worn through to raw substrate. In a climate with this much rain and this much salt exposure, that maintenance window matters more, not less.
James Hardie's ColorPlus finish is factory-baked onto the fiber cement panel itself, not field-applied, and it's engineered to hold color and resist the coastal conditions here for far longer stretches before it needs attention. It's not that Hardie never needs maintenance — it's that the baseline maintenance burden is lower and the material underneath the finish doesn't react to moisture the way wood fiber does.
Side-by-Side: What We're Actually Weighing
| Factor | LP SmartSide | James Hardie Fiber Cement |
|---|---|---|
| Core material | Engineered wood strand/fiber | Cement, sand, cellulose fiber |
| Combustibility | Combustible (wood-based) | Non-combustible |
| Moisture response | Can swell/degrade if edges or seams aren't sealed | Doesn't swell or rot from moisture exposure |
| Finish | Primed at factory; paint applied/maintained in the field | Factory-baked ColorPlus finish available |
| Installation sensitivity | High — edge sealing and flashing details are critical | Lower — more forgiving of minor field variance |
| Typical repaint cycle | Shorter, climate-dependent | Longer with ColorPlus factory finish |
| Coastal/salt-air track record | Performs best with strict maintenance | Purpose-built HZ5 line for wet, marine climates |
| Relative installed cost | Generally lower | Generally higher |
Warranty Structure: Read the Fine Print Either Way
This is true of both products, and it's worth saying plainly: engineered wood and fiber cement warranties are both conditioned on correct installation. Where they differ is what "correct installation" is actually protecting against. On LP SmartSide, the installation requirements exist largely to keep moisture out of a wood-based core. On Hardie, the requirements exist mostly to protect finish integrity and joint performance, since the core material itself isn't vulnerable to rot the same way.
James Hardie also backs its ColorPlus finish with a separate, transferable finish warranty in addition to the product warranty — meaning if you sell the home, the next owner isn't starting from zero. That transferability is a real, tangible value in a market like Semiahmoo's, where waterfront and near-waterfront homes turn over regularly.
What We Install Instead, and Why
We standardized on James Hardie's HZ5 product line, which is specifically engineered for wetter, harsher climates like the Pacific Northwest coast. It's non-combustible, doesn't swell or rot from water exposure the way wood-based products can, and holds its factory finish for a long time without the same repainting cycle. For a house sitting exposed to Semiahmoo Bay's wind and salt air, that's the difference between siding that shrugs off the climate and siding that requires a homeowner to stay on top of maintenance to get full value out of it.
That's the whole reasoning. We're not saying LP SmartSide is a bad product everywhere — we're saying that for the specific combination of salt air, driving rain, and a long moss season that defines this part of Whatcom County, we'd rather install the product that's engineered for exactly these conditions and stand behind it, than install something that asks a homeowner to manage more risk over time.
Questions Worth Asking Before You Choose a Siding Material
- Does the product's manufacturer specifically rate it for marine or high-moisture climates, or is that a general claim?
- What edge-sealing, flashing, and clearance details does the manufacturer require, and will the contractor put that in writing?
- Is the finish factory-applied or field-applied, and what's the realistic repaint/recoat interval in a climate like ours?
- Is the warranty transferable if you sell the home?
- What happens to the warranty if a future owner or handyman does uninspected repairs or additions?
- How does the material perform under sustained shade and moss growth on north-facing walls?
- Is the installing crew certified or specifically trained on this product's details, not just general siding experience?
Cost Is Part of the Conversation, Not the Whole Conversation
We're not going to pretend fiber cement is the cheaper option up front — it typically isn't. But the honest way to compare siding materials isn't first-cost alone, it's first-cost plus the maintenance and recoating burden over the years you'll own the house. In a climate that pushes moisture at your walls as consistently as this one does, a lower-maintenance material tends to close some of that cost gap over a 15-20 year window, even before factoring in peace of mind about moisture performance.
If you're weighing siding options for a home in Semiahmoo or anywhere in Whatcom County, we're happy to walk your specific house, talk through exposure, overhangs, and sun/shade patterns, and give you a straight answer about what we'd recommend and why. Reach out for a free, no-pressure estimate using the form below.