Semiahmoo Exterior Homeowners in Semiahmoo and around Whatcom County ask us about LP SmartSide fairly often, usually after seeing it at a home center or getting a quote from another contractor that includes it as a budget option. It's a legitimate, widely used engineered wood siding product, and we're not going to pretend otherwise. But we don't install it, and we think you deserve a straight answer about why — not a sales pitch dressed up as "education."
This page walks through what LP SmartSide actually is, what it does well, where it runs into trouble in our specific climate, and why our company standardized on James Hardie fiber cement instead. Our goal isn't to scare you off engineered wood siding everywhere in the country. It's to explain the trade-offs that matter here, on the water, in a marine climate that doesn't give any siding product much of a break.
What LP SmartSide Actually Is
LP SmartSide is an engineered wood product — strand board or OSB-type substrate treated with resins, waxes, and zinc borate for insect and moisture resistance, then coated with a resin-saturated overlay and factory primer. It comes in lap siding, panels, and trim, and it's manufactured to look like traditional wood clapboard or board-and-batten at a lower material cost than real wood or fiber cement.
To LP's credit, the product has come a long way since the OSB siding failures of the 1990s that gave engineered wood a bad name industry-wide. Modern SmartSide carries a real warranty, holds paint reasonably well when installed and maintained correctly, and is easier to cut and nail than fiber cement — which is part of why it's popular with builders working on tight schedules and tight budgets.
Where It Genuinely Performs Well
- Lower material and labor cost than fiber cement or real wood
- Lighter weight, easier and faster to install
- Won't crack from impact the way fiber cement can in shipping or handling
- Reasonable warranty coverage from the manufacturer when installation guidelines are followed exactly
- Wide range of textures and profiles that mimic traditional wood siding
If we operated in a dry inland climate with moderate humidity, we'd have an easier time recommending it. That's not the climate Semiahmoo sits in.
Why Our Climate Changes the Calculation
Salt Air and Moisture Load
Semiahmoo sits right on Semiahmoo Bay, and homes here take on a level of airborne salt and moisture that inland Whatcom County properties simply don't deal with. Salt air accelerates the breakdown of coatings and fasteners, and it keeps building surfaces damp longer after rain or fog than drier climates would. Engineered wood siding is, at its core, wood fiber — and wood fiber's biggest enemy is sustained moisture exposure at cut edges, seams, and fastener penetrations.
Driving Rain and Wind-Driven Wetting
This stretch of the Washington coast gets driving rain off the Strait of Georgia and Boundary Bay, which pushes water sideways into siding laps and joints rather than letting it run straight down and off. Any engineered wood product is only as good as its factory seal and field-applied caulking at every cut edge — and every cut edge, nail penetration, and butt joint on a real job site is a place where that seal can be compromised.
Moss Season
Whatcom County's long wet season, roughly October through May, means siding surfaces stay shaded, damp, and cool for months at a stretch — exactly the conditions moss and algae need to take hold. Moss holds moisture directly against a siding surface far longer than open air would, and that sustained contact is much harder on a wood-fiber substrate than it is on a cementitious one.
The Real-World Trade-Offs We See With Engineered Wood
None of this means SmartSide is a bad product in the abstract. It means the failure modes that matter most — edge swelling, seam separation, and coating breakdown — are all moisture-driven, and our region provides moisture in more forms and for more months of the year than almost anywhere else in the continental U.S.
| Factor | LP SmartSide (Engineered Wood) | James Hardie (Fiber Cement) |
|---|---|---|
| Core material | Wood strand/OSB substrate with resin overlay | Cement, sand, and cellulose fiber — non-combustible |
| Moisture sensitivity | Vulnerable at cut edges and unsealed penetrations | Dimensionally stable; unaffected by moisture swelling |
| Cut edge treatment required | Yes — field sealing mandatory at every cut | Recommended but far less critical to long-term performance |
| Insect resistance | Treated, but still an organic substrate | Not a food source for insects |
| Factory finish option | Primed; field paint typically required | ColorPlus baked-on finish available, no field paint needed |
| Fire rating | Combustible, treated substrate | Non-combustible |
| Typical material cost | Lower | Moderate to higher |
| Warranty structure | Manufacturer warranty, installation-dependent | Strong transferable warranty on substrate and finish |
Installation Sensitivity Is the Real Issue
Engineered wood siding's performance is heavily dependent on installation precision — every cut edge sealed, every fastener placed correctly, every joint flashed and caulked to spec, year after year of maintenance to keep coatings intact. On a dry-climate job, a missed detail might not matter for a decade. On a Semiahmoo job three blocks from the water, a missed detail at a butt joint can start showing edge swelling within a few seasons.
We install year-round in this climate, and we've built our crews, our details, and our warranty backing around a product where the substrate itself isn't the weak point. That's a business decision as much as a technical one: we don't want to be the crew that has to explain callback issues five years down the road because a fastener pattern or a caulk joint didn't hold up to salt air and moss season indefinitely.
Maintenance Burden Over Time
SmartSide requires ongoing homeowner maintenance to perform as designed:
- Repainting or recoating on a regular cycle, more frequently in coastal exposure
- Inspecting and resealing cut edges and joints periodically
- Prompt attention to any moss or algae growth before it holds moisture against the surface
- Watching for early signs of edge swelling at laps, corners, and trim intersections
- Keeping gutters, downspouts, and grade clearance in good shape to limit splash-back and standing moisture
Fiber cement isn't maintenance-free either — it still needs periodic painting and normal upkeep — but it doesn't carry the same substrate risk if a maintenance cycle gets pushed back a year or two, which happens in real life more often than any of us would like to admit.
Why We Standardized on James Hardie
We install James Hardie fiber cement exclusively, and it comes down to matching the product to the environment we actually work in. Hardie's HZ5 product line is engineered specifically for climates with high moisture exposure and freeze-thaw cycling, which describes Whatcom County's marine climate well. Fiber cement doesn't rot, doesn't feed insects, and doesn't swell at cut edges the way wood-based products can — because its substrate isn't organic in the first place.
ColorPlus factory finish gives homeowners a baked-on, UV-cured coating with a much longer service life than field-applied paint, and it comes with its own finish warranty separate from the substrate warranty. For a home sitting in salt air with a long moss season overhead, that combination of non-combustible substrate and factory-cured finish is what we're willing to put our name and our warranty behind.
We're not telling you LP SmartSide is a scam or that everyone who installs it is doing bad work. We're telling you why, after years of working exclusively in this coastal, wet, salt-exposed climate, we made a deliberate choice to install one product system and get very good at it, rather than offer several tiers with meaningfully different long-term risk profiles.
Questions to Ask Any Contractor Before You Commit
- What siding substrate are you recommending for a home in a coastal, high-moisture climate specifically?
- How is the manufacturer's warranty affected if cut edges or field seams aren't sealed exactly to spec?
- Does the warranty transfer if you sell the home within the coverage period?
- What's the realistic repainting or recoating interval for this product in a salt-air, high-moss environment?
- Is the finish factory-applied or field-applied, and how does that affect long-term appearance?
If you're weighing siding options for a home in Semiahmoo or anywhere else in Whatcom County, we're glad to walk through what we see on the ground here and why we install what we install. Reach out for a free, no-pressure estimate — we'll look at your home's specific exposure and give you an honest read on what it needs.