Bellingham Two Very Different Answers to the Same Problem
Walk into any siding supplier in Whatcom County and you'll find two products competing for the same job: keeping moisture out, holding paint, and surviving decades of Pacific Northwest weather. James Hardie fiber cement and LP SmartSide engineered wood both promise durability at a lower cost than real wood. They are built on fundamentally different materials, though, and that difference matters a lot more here than it does in a dry climate.
We install exclusively James Hardie fiber cement siding. This page explains what SmartSide actually is, where it performs well, and why the specific conditions in Bellingham — salt air off Bellingham Bay, driving rain, and a moss season that can run half the year — pushed us to standardize on fiber cement instead.
What LP SmartSide Actually Is
LP SmartSide is an engineered wood product. It starts as wood strands, usually from fast-growing species, bonded together with resins and waxes under heat and pressure, then finished with a treated overlay called SmartGuard for insect and moisture resistance. It's a legitimate product with real engineering behind it, and LP has improved its moisture resistance significantly since the OSB siding failures of the 1990s that gave engineered wood a bad reputation industry-wide.
Where it wins: SmartSide is lighter than fiber cement, easier on installation crews, and takes fasteners with less pre-drilling. It's also generally less expensive up front. For homeowners in drier regions, or on projects where the budget ceiling is hard, it's a reasonable choice.
The Trade-Off Is Wood's Core Nature
Underneath the resin treatment, SmartSide is still a cellulose-based product. Wood fiber swells when it takes on moisture and shrinks when it dries out. The SmartGuard treatment slows water absorption at the surface, but it doesn't change what happens if water gets past a compromised seal — at a cut edge, a fastener hole, a butt joint, or a spot where caulk has failed. Once moisture reaches untreated wood fiber, the same swelling and softening that affects any wood product can begin.
That's a manageable risk in Arizona. It's a real one in a maritime climate where wood siding can go weeks without a fully dry day during our wet season, and where wind-driven rain off the bay hits west- and south-facing walls at an angle that pushes water into every gap a normal rain doesn't reach.
What James Hardie Fiber Cement Is Made Of
Hardie siding is roughly 90% Portland cement, sand, and cellulose fiber, autoclaved into a rigid, stable board. There is no wood fiber exposed at the surface to absorb water and swell. Cut edges do need to be sealed with Hardie's touch-up product or primer, and joints and fasteners still need to be installed correctly — fiber cement is not maintenance-free or installation-proof. But the base material itself doesn't rot, doesn't provide a food source for insects, and doesn't support mold growth the way a cellulose-based product can if moisture sits against it.
It's also non-combustible, which matters given how many Whatcom County properties border trees and vegetation, and it holds a factory-applied ColorPlus finish that's baked on and warranted separately from the substrate — a different proposition than field-applied paint on any siding material.
HZ5 and the Northwest Climate Engineering
Hardie doesn't sell one product nationwide. Its HZ (HardieZone) system is engineered by climate zone, and most of the Pacific Northwest, including Whatcom County, falls into HZ5 — the zone built for prolonged damp and freeze-thaw cycling. That's a meaningful distinction from a generic national siding spec, because the product is formulated with this exact weather pattern in mind rather than adapted after the fact.
Why Bellingham's Climate Is the Deciding Factor
Three conditions specific to this area drove our decision more than any national comparison chart:
- Salt air: Properties near Bellingham Bay and the waterfront take in airborne salt that accelerates corrosion of fasteners and finishes, and can work into any exposed wood fiber over time.
- Driving rain: Storms coming off the Salish Sea don't just fall straight down — wind pushes rain sideways into wall assemblies, stressing every seam, joint, and penetration far more than a calm vertical rain would.
- Moss season: Whatcom County's shaded, moisture-retentive conditions support moss and algae growth on siding for a large part of the year. Moss holds water against the surface, which is a much bigger problem for a material that can absorb it than one that can't.
None of these conditions is disqualifying for SmartSide on their own — plenty of SmartSide siding performs fine in wetter climates when it's detailed and maintained correctly. But stacked together, and multiplied across a maritime county where "correctly maintained" has to hold up year after year with minimal homeowner intervention, we decided fiber cement was the product we were willing to put our name behind.
Side-by-Side: What Actually Differs
| Factor | James Hardie Fiber Cement | LP SmartSide Engineered Wood |
|---|---|---|
| Core material | Cement, sand, cellulose fiber (non-wood-fiber surface) | Wood strands with resin treatment |
| Moisture behavior | Does not swell/rot; edges need sealing | Resistant at treated surface; vulnerable if water reaches untreated wood fiber |
| Fire rating | Non-combustible | Combustible, treated wood product |
| Weight/installation | Heavier; requires pre-drilling in some applications | Lighter; faster to install |
| Finish | Factory-baked ColorPlus, separately warranted | Factory primer or field-applied paint, typically |
| Upfront cost | Higher material cost | Generally lower material cost |
| Climate engineering | HZ5 formulation for Pacific Northwest conditions | Single national product line |
Installation Sensitivity Matters More Than the Spec Sheet
Both products fail the same way when installed poorly: unsealed cuts, missing flashing, caulk used as a substitute for proper drainage detailing, or fasteners driven wrong. The difference is what happens after a small installation flaw lets water in. On fiber cement, a compromised joint is a maintenance item. On any wood-based product, it's an entry point to material that can absorb, swell, and eventually deteriorate from the inside — often invisibly, until paint starts failing or a soft spot shows up years later.
This is a big part of why we chose to specialize rather than offer both. Installing two materially different systems well means maintaining two different skill sets, two different detailing standards, and two different sets of judgment calls about flashing and clearances. We'd rather install one system exceptionally well than split our crews' expertise across two.
What Correct Fiber Cement Installation Involves
Buying Hardie siding doesn't guarantee Hardie performance — installation quality determines most of what a homeowner actually experiences over the life of the siding. A few non-negotiables:
- Proper weather-resistive barrier and rain screen gap behind the siding, not siding fastened directly to sheathing
- Correct fastener type, spacing, and depth per Hardie's published installation specs
- All cut edges primed or sealed before installation, not after
- Flashing at every window, door, and horizontal trim intersection
- Minimum clearance from grade, decks, and roof lines to keep siding out of standing water and splash-back
- Caulk used only where specified, not as a substitute for proper flashing and overlap
Cost Over Time, Not Just at Install
SmartSide's lower upfront price is real. What it doesn't always account for is repainting cycles, more careful caulk maintenance around joints and penetrations, and the risk profile if a moisture problem does develop in a wood-fiber product. Hardie's ColorPlus finish is designed to extend the repaint interval well beyond typical field-applied paint, and the substrate itself doesn't carry the same rot risk if a small installation flaw goes unnoticed for a season. Over a 20-30 year ownership horizon in this climate, that gap in maintenance burden and risk is the core of our reasoning — not the sticker price on install day.
Where This Leaves You as a Homeowner
If you're comparing bids and one contractor is proposing SmartSide at a lower number, that's not necessarily a bad-faith offer — it's a legitimate product, priced accordingly. Ask what climate zone product they're specifying, how cut edges will be sealed, and what the warranty actually covers if moisture does get behind the siding. Those answers will tell you more than the brand name will.
We made our decision based on what we're comfortable standing behind in Whatcom County's specific combination of salt air, wind-driven rain, and a moss season most of the country doesn't deal with. If you want to talk through what that means for your specific home, we're happy to walk your siding with you and give you a straight answer — request a free, no-pressure estimate below.