Bellingham Siding Two Different Materials, Two Different Bets on Moisture
When homeowners in Bellingham ask us why we don't install engineered wood siding like LP SmartSide, it's a fair question. It's a legitimate product used successfully across the country, and we're not here to trash it. But we install exteriors in Whatcom County, where salt air off Bellingham Bay, long stretches of driving rain, and a moss season that can run half the year put real, sustained pressure on a home's siding. That local reality shaped which material we chose to stand behind, and it's worth explaining honestly.
What Engineered Wood Siding Actually Is
LP SmartSide and similar products are made from strand board, wood fibers, or wood chips bonded with resins, then treated with zinc borate for insect and fungal resistance and finished with a factory primer or coating. It cuts and handles like wood, it's lighter than fiber cement, and many crews find it faster to install. For the right climate and the right maintenance schedule, it can perform well for years.
The trade-off is fundamental to the material: it's still wood-based. Wood swells when it takes on moisture and shrinks when it dries out. The zinc borate treatment and factory coating are there specifically to manage that risk, which tells you the risk is real. If water gets past the surface coating at a cut edge, a fastener hole, a butt joint, or a spot where caulking has failed, the substrate underneath can begin to absorb it. Once that starts, the damage isn't always visible until it's advanced.
Why That Matters More in Whatcom County
Every siding product depends on installation quality and ongoing maintenance, but engineered wood asks for a stricter, more continuous maintenance relationship than fiber cement does. Caulking has to be inspected and refreshed on a schedule. Cut edges have to be sealed at install and re-sealed if that seal ever opens up. Paint has to be maintained so the coating keeps doing its job.
That's a manageable routine in a dry climate. It's a much harder routine to keep up with here. Bellingham gets sustained fall and winter rain, often driven sideways by wind off the water, and the marine air carries salt that accelerates wear on caulk, fasteners, and finishes. On top of that, our shaded, damp lots grow moss and algae readily, and organic growth holds moisture against a wall longer than a dry surface would. Miss a maintenance cycle or two on an engineered wood exterior in this climate, and you're not just risking cosmetic wear — you're risking the water intrusion the whole system was designed to prevent.
Why We Standardized on James Hardie Fiber Cement
Fiber cement is made from cement, sand, and cellulose fiber, cured into a rigid, dimensionally stable board. It doesn't swell, warp, or rot the way a wood-based product can, and it's non-combustible, which matters to a lot of homeowners regardless of climate. For Whatcom County specifically, a few things stand out:
- Moisture behavior: Fiber cement doesn't absorb and hold water the way wood fiber does, so an isolated failure point — a nick in the caulk, a slightly open joint — doesn't carry the same risk of the substrate itself swelling or breaking down.
- Climate-engineered product lines: James Hardie makes HZ5 boards specifically engineered for wetter climate zones like ours, rather than a one-size-fits-all formulation.
- Factory-applied ColorPlus finish: baked-on color and finish that resists fading and holds up against moss, algae, and salt air better than a field-applied coating, and doesn't put homeowners on the hook for a repaint schedule the way primed products can.
- Long, transferable warranty: Hardie backs its siding with a strong warranty structure, and one that's designed to hold up under real Pacific Northwest exposure, not best-case conditions.
Correct Installation Still Matters
None of this means fiber cement is maintenance-free or installation-proof. Hardie siding performs the way it's supposed to only when it's installed to the manufacturer's specifications — correct clearances above grade and roof lines, proper flashing and house wrap behind it, correct fastener placement, and joints and butt seams treated the way Hardie's install guide calls for. A poorly installed fiber cement job can still let water in behind the cladding. The advantage isn't that the material makes installation quality optional — it's that the material itself doesn't become part of the moisture problem once water gets past a flaw.
Our Bottom Line
We didn't stop installing engineered wood siding because it's a bad product. We stopped because we wanted to put one material on Whatcom County homes that we could stand behind fully, in a climate that includes salt air, sustained rain, and a long moss season every single year. Fiber cement, installed correctly, gives us that confidence. It's a straightforward professional judgment call, and we think it's the honest one.
If you're weighing siding options for a home in Bellingham or elsewhere in Whatcom County, we're happy to walk through what we saw on your specific house and why we'd recommend what we recommend. Reach out for a free, no-pressure estimate using the form below.