Lynden Exterior What LP SmartSide Is (And Why It Gets Specified So Often)
LP SmartSide is an engineered-wood siding product — strands of wood fiber bonded with resin, formed into panels or lap boards, then coated with a resin-saturated overlay and factory primer. It's lighter than fiber cement, easier on saw blades, and costs less per square foot installed. A lot of builders in Whatcom County like it for those reasons, especially on production-built homes where speed and budget matter more than a 40-year outlook.
We're not here to tell you LP SmartSide is a bad product when it's made and installed correctly. LP has put real engineering into their SmartGuard process, and the company backs it with a legitimate limited warranty. It has a place in the market. It's just not the product we put on Lynden homes, and we think homeowners deserve the actual reasoning, not a sales pitch.
The engineered-wood strand technology
SmartSide's core is Strand Technical Substrate — wood strands oriented and pressed under heat, similar in spirit to OSB but proprietary to LP's process. The zinc-borate treatment resists fungal decay and termites, and the resin-saturated surface is meant to resist moisture absorption better than untreated wood. On paper, that's a reasonable answer to the classic weakness of wood siding: it rots when water gets in and stays in.
Where it performs well
In drier climates, or on homes with generous roof overhangs and well-maintained paint, SmartSide can hold up for years with no drama. The issue isn't the product in isolation — it's the product against Whatcom County's specific weather pattern, day in and day out, for decades.
The Core Trade-Off: Wood-Based Substrate in a Wet Climate
Every engineered-wood product shares one unavoidable fact: wood strands, no matter how they're treated, swell when they absorb water and don't fully return to their original dimension once they dry. Do that cycle enough times — freeze, thaw, soak, dry — and you get gradual swelling at joints, fastener holes, and cut edges. It's slower than it would be with raw untreated lumber, but it's the same physical process underneath the treatment.
James Hardie's fiber cement siding is made from cement, sand, and cellulose fiber — no wood strands to swell, no organic substrate for moisture to work into. That's the single biggest reason we standardized on it. It's not that Hardie is immune to weather; nothing is. It's that the failure mode we see most often in this region — moisture intrusion at poorly sealed edges — simply doesn't apply to fiber cement the way it applies to any wood-based product.
Whatcom County's moisture load
Lynden sits inland from Bellingham Bay but still gets the full marine push off the Salish Sea — driving rain that comes in sideways during fall and winter storms, salt-laden air carried in from the Strait of Georgia, and a stretch of months where surfaces rarely get a full dry-out. That combination is exactly the stress test that separates products that look fine in a showroom from products that hold up on an actual roofline for 20-plus years.
Edge and Cut-Site Vulnerability
Engineered wood siding is manufactured with factory-sealed edges and a protective overlay on the face. The problem is what happens on the job site: every butt joint, every window and door cut, every corner trim intersection exposes raw, unsealed substrate. If that cut edge isn't caulked and primed correctly — and kept that way with regular maintenance — it becomes the entry point for water. Once water gets into the strand core at a cut edge, it travels, and by the time you see the bulge or the soft spot on the face of the board, the damage has been happening for a while underneath the paint.
Fiber cement has the same job-site reality — it gets cut on site too — but a cut edge in fiber cement doesn't have organic material to break down. Worst case with a poorly sealed Hardie cut is a paint touch-up issue, not a rot pathway.
| Factor | LP SmartSide (engineered wood) | James Hardie (fiber cement) |
|---|---|---|
| Core material | Wood strand composite, resin-bonded | Cement, sand, cellulose fiber |
| Cut-edge risk | Exposed substrate must be sealed every time, or moisture entry begins | No organic substrate to rot; sealing is about paint longevity, not structural failure |
| Combustibility | Combustible (treated wood product) | Non-combustible |
| Swelling/expansion over time | Some swelling at joints and fasteners is normal over decades | Dimensionally stable; minimal expansion/contraction |
| Typical manufacturer warranty | Limited warranty, often prorated after early years | Non-prorated limited warranty, transferable |
| Factory finish option | Primed; field paint required for full protection | ColorPlus factory-baked finish available, reduces field-paint dependency |
Field Installation Sensitivity
SmartSide's performance is more dependent on flawless field installation than fiber cement is. That's not a knock on the crews who install it — it's a statement about how much room for error the product tolerates. Miss a caulk joint, nail too close to an edge, or leave a cut end unsealed on a rainy install day, and you've created a weak point that won't show itself for a year or two. We don't like putting a product on someone's home where the difference between a 25-year performance and a 10-year problem comes down to whether every single joint was sealed perfectly on a job site in the rain.
What correct installation actually requires
- Every field cut, factory or job-site, sealed with the manufacturer-specified primer or sealant before installation
- Proper clearance from grade, roofing, decks, and other water-collecting surfaces
- Correct fastener placement and depth — over-driven or under-driven fasteners both create problems
- Butt joints flashed or sealed per spec, not just butted and caulked on the surface
- Ongoing homeowner maintenance: caulk inspection, repainting on a schedule, prompt repair of any impact damage
- No skipped primer touch-up at any point where the factory coating is breached
That's a long list of "don't skip this" items, and on a home in a climate that's wet more months than it's dry, skipping even one has consequences down the road.
Moss, Salt Air, and the Long Wet Season
Anyone who's owned a home in Lynden for a few years knows the moss problem — north-facing walls, shaded eaves, and anywhere air doesn't move freely will grow moss and algae if the surface holds moisture. On a painted wood-composite surface, moss growth sits directly against a substrate that can be damaged by sustained dampness. On fiber cement, moss and mildew are a cosmetic cleaning issue, not a structural one. The salt air off the Strait adds another layer: airborne salt accelerates coating breakdown on painted surfaces generally, which means the paint film protecting an engineered-wood substrate needs more frequent attention here than it would in an inland, drier county.
Warranty Structure Comparison
Read the fine print on any siding warranty before you sign a contract — this is one of the most overlooked parts of a siding decision. Engineered wood warranties commonly step down in coverage the longer you own the home (prorated), and many exclude damage tied to improper field sealing, which is difficult for a homeowner to prove either way after the fact. James Hardie's warranty on its fiber cement products is non-prorated for its stated term and is transferable to a subsequent homeowner, which also matters for resale — a buyer's inspector or agent will ask about siding warranty status, and a strong, transferable one is a selling point.
Why We Standardized on James Hardie Instead
We made a decision a long time ago to install one siding system and install it right, rather than offer every product on the market and hope each one gets a flawless installation. James Hardie fiber cement is non-combustible, dimensionally stable, and doesn't have an organic substrate that can rot from the inside out. The ColorPlus factory finish is baked on under controlled conditions — not brushed on in the field on whatever day the weather cooperates — and it carries its own separate finish warranty on top of the product warranty. Hardie's HZ5 product line is engineered specifically for climates like ours: freeze-thaw cycling, sustained moisture, and coastal exposure. For a house that's going to sit through 25-plus Lynden winters, that's the standard we're willing to put our name behind.
What This Means for Your Project
If you already have LP SmartSide on your home and it's performing fine, that's genuinely good news — not every installation fails, and a well-installed, well-maintained system can last for years. We're not in the business of telling you to rip off siding that's working. Where this matters most is when you're planning new construction, a full re-side, or replacing damaged siding and choosing what goes up next. That's the decision point where we'll tell you honestly what we've seen and why we only stand behind one product.
If you're weighing siding options for a home in Lynden or anywhere in Whatcom County, we're glad to walk your house, point out the specific exposure spots — north walls, low overhangs, areas that catch wind-driven rain — and explain what we'd recommend and why. Reach out for a free, no-pressure estimate and we'll give you our honest read on your project.