Sudden Valley Siding What LP SmartSide Actually Is
LP SmartSide is an engineered wood siding product — strand-based wood fiber, resin, and wax pressed together and coated with a treated overlay, then finished with a factory primer or pre-finished coating. It's a step up from old-school hardboard siding, and LP has spent real engineering effort making it more resistant to moisture and fungal decay than the composite sidings that gave engineered wood a bad name in the 1990s. It comes in lap boards, panels, and trim, it's lighter than fiber cement, and it's easier on saw blades and installer backs. None of that is a knock on the product's intent.
We get asked about LP SmartSide often enough that it's worth a straight answer: we don't install it. Not because it's a scam or because every SmartSide job fails. It's because of how it behaves specifically in Whatcom County's climate, and because we've made a business decision to install one product system — James Hardie fiber cement — and stand behind it fully rather than juggle warranties and installation specs across multiple siding lines.
The Core Issue: It's Still Wood
Strip away the engineering and SmartSide is wood fiber held together with resin. Wood fiber, even treated and bonded, swells when it takes on water and shrinks when it dries out. The zinc borate treatment LP uses helps resist rot and insect damage, but it doesn't change the fundamental physics of a cellulose-based product sitting outside in a wet climate for decades.
That matters more here than it does in Arizona or inland Texas, where most of LP's marketing photos were probably shot. Sudden Valley sits close enough to Lake Whatcom and the broader Puget Sound air mass that homes deal with salt-laden air, long stretches of driving rain off the water, and a moss and algae season that can run eight or nine months out of the year. Any siding product installed here needs to tolerate near-constant moisture exposure and cycles of wetting and drying, not just occasional rain.
Edge Sealing Is Everything — and Easy to Get Wrong
LP SmartSide's warranty and performance depend heavily on every cut edge, especially at butt joints, corners, and penetrations, being properly primed and sealed at time of installation. Miss one edge, and that's the spot where water gets into the fiber and starts the swelling and delamination process. On a large home with a lot of trim, corners, and window returns, that's dozens of cut edges that all have to be treated correctly, every time, by every crew member, for the life of the installation.
We're not saying installers can't do this correctly. Plenty do. But it's a product where the margin for error is thin and the consequence of a missed edge doesn't show up for a few years, by which time it's a warranty argument instead of a five-minute fix. We'd rather install a product where the moisture-resistance doesn't hinge on perfect field sealing of every cut.
Moss, Algae, and a Damp Climate
Whatcom County's combination of shade, humidity, and mild temperatures is close to ideal for moss and algae growth on exterior surfaces. Engineered wood siding, even with a factory finish, has a more porous, more organic surface than fiber cement, and it tends to hold moisture at the surface longer after rain. That combination — organic substrate plus sustained dampness — is exactly what moss and mildew need to get established.
Homeowners with SmartSide in wetter Pacific Northwest microclimates often end up on a more active maintenance schedule: periodic washing, inspecting caulked joints, and repainting or recoating sooner than they'd expect from the marketing. That's not a defect in the product so much as a mismatch between where it performs best and where a lot of it gets installed anyway.
What Regular Maintenance Actually Looks Like
- Annual visual inspection of all cut edges, seams, and caulk joints for gaps or cracking
- Re-caulking exposed joints every few years as caulk ages and shrinks
- Washing down north-facing and shaded elevations more often to control moss and algae buildup
- Repainting or recoating on a shorter cycle than fiber cement typically requires
- Prompt repair of any impact damage before moisture can get into the exposed fiber
Fire Resistance: A Real Difference
This one isn't about local climate, but it's worth being direct about. LP SmartSide is a combustible wood product, engineered and treated, but wood. James Hardie fiber cement is non-combustible — it's roughly 90% sand, cement, and cellulose fiber, and it doesn't contribute fuel to an exterior fire the way wood-based siding can. For homeowners weighing insurance considerations or simply wanting one less combustible material on their exterior, that's a meaningful structural difference between the two products, not a marketing point.
Installation Sensitivity and Warranty Structure
LP backs SmartSide with a limited warranty, but like most engineered wood products, the fine print ties coverage to installation being done exactly to LP's specifications — correct fastening, correct clearances, correct edge treatment, approved caulks and primers. Deviate from the install manual and you can end up with a warranty that looks solid on paper but is hard to actually collect on if something goes wrong five or ten years down the road.
Fiber cement has its own installation requirements too — nobody's siding is truly install-proof — but James Hardie's HZ5 product line is specifically engineered for the Pacific Northwest's freeze-thaw and moisture cycle, and the company backs it with a non-prorated limited warranty that's transferable to a subsequent homeowner. That combination of climate-matched engineering and a warranty that survives a home sale is a big part of why we standardized on it.
Side-by-Side: What You're Actually Choosing Between
| Factor | LP SmartSide | James Hardie Fiber Cement |
|---|---|---|
| Core material | Engineered wood strand, resin-bonded | Cement, sand, cellulose fiber |
| Combustibility | Combustible | Non-combustible |
| Moisture behavior | Resists rot when properly sealed; vulnerable at exposed cut edges | Dimensionally stable, engineered for wet climates (HZ5) |
| Moss/algae resistance in PNW damp climates | Moderate; more porous surface, shorter maintenance cycle | Better; denser surface, ColorPlus finish sheds growth more readily |
| Finish | Factory primed or pre-finished; repaint cycle typically shorter | Baked-on ColorPlus finish with longer color/finish warranty |
| Warranty transferability | Limited, spec-dependent | Non-prorated, transferable |
| Upfront material cost | Generally lower | Generally higher |
Why Cost Alone Doesn't Settle It
We won't pretend LP SmartSide isn't cheaper to buy and often cheaper to install — it's lighter, it cuts easier, and the material itself typically costs less per square foot than fiber cement. If budget is the only factor, that price gap is real and we understand why it's tempting.
But siding is a twenty-to-thirty-year decision, and in a climate like Whatcom County's — where a home might see 40-plus inches of rain a year, salt air off the Sound, and moss pressure nearly year-round — the lower upfront cost of an engineered wood product can get eaten up by a shorter maintenance and repaint cycle, and by the risk of edge-sealing failures that are expensive to diagnose and fix once they start. We'd rather have that conversation honestly up front than sell a homeowner something we don't think holds up here.
Why We Install James Hardie Instead
We standardized on James Hardie fiber cement for a specific set of reasons that line up with our local conditions:
- Non-combustible, which matters both structurally and for insurance considerations
- HZ5 product engineering built for freeze-thaw and high-moisture climates like ours
- ColorPlus factory finish that resists fading and holds up against moss and mildew better than field-primed wood products
- A single, well-documented install spec our crews follow consistently, rather than juggling different manufacturers' edge-sealing and fastening requirements
- A non-prorated, transferable limited warranty that still means something if the home sells in ten or fifteen years
Installing one product system well, on every job, is how we keep our workmanship and the manufacturer's warranty aligned instead of working against each other.
What This Means for Your Project
If you've already got LP SmartSide on your home and it's holding up, we're not telling you to rip it off early — good SmartSide installations with well-maintained edges and finish can last a long time. This page is about what we choose to install on new work and full replacements, not a verdict on every SmartSide job in Sudden Valley. If you're planning a re-side and want to understand the real trade-offs between engineered wood and fiber cement for a home in this specific climate, we're happy to walk the exterior with you and talk through it plainly — no pressure, no scare tactics, just what we'd do on our own house. Reach out for a free estimate and we'll give you a straight read on your siding and what we'd recommend.