Ferndale Exterior Composite Decking in Kendall: Built for What This Climate Actually Does to a Deck
Kendall sits far enough inland from the Strait that people sometimes assume salt air isn't a factor here. It still is, just in a different form than what a waterfront home deals with directly on Bellingham Bay. Add in Whatcom County's long wet season, moss that colonizes anything shaded or north-facing, and the freeze-thaw swings that show up in the foothills near Kendall more than they do closer to the water, and you've got a deck environment that punishes shortcuts. Composite decking earns its keep here, but only when it's installed with this specific climate in mind — not installed the same way a crew would build a deck in a dry inland state and then shipped up to Ferndale.
This page is about composite decking specifically for Kendall properties: what the moisture and moss cycle does to a deck over years, what a correct composite installation actually involves, and why the substructure and drainage details matter more here than the decking brand itself.
What Kendall's Climate Actually Does to a Deck Over Time
Every deck material problem we see in this area traces back to one of three things: standing moisture, restricted airflow, or organic buildup that holds water against a surface. Kendall gets all three.
Moss and Organic Growth
Whatcom County's wet season runs long, and Kendall's tree cover and rural lot layouts mean a lot of decks sit partially shaded for much of the year. Moss and algae don't just look bad — they hold moisture against the decking surface and, on the boards themselves, can make even a slip-resistant composite surface genuinely slick. On wood, moss growth accelerates rot at the point of contact. On composite, it's mostly cosmetic and a slip hazard, but only if the board's surface texture and drainage gaps are doing their job.
Driving Rain and Wind-Driven Moisture
Rain here doesn't always fall straight down. Wind off the Strait and through the valley pushes moisture sideways, which means it gets up under railings, behind fascia boards, and into ledger connections that a calmer climate wouldn't stress the same way. Any gap in flashing or sealant at the house connection becomes a chronic moisture entry point, and that's true whether the decking on top is wood or composite.
Freeze-Thaw at the Substructure
Kendall sits at a slightly higher elevation and further from the moderating effect of the water than coastal Ferndale, so it sees a few more freeze-thaw cycles per winter. That matters most for footings and fasteners — water that gets into a post base or a joist hanger and freezes will work a connection loose over a few seasons. Composite boards themselves don't absorb water the way wood does, but the frame underneath them is still wood or metal, and it's still exposed to this cycle.
Why the Substructure Matters More Than the Decking Brand
Homeowners researching composite decking usually focus on board brand and color first. That's understandable, but in this climate the framing underneath is what determines whether the deck lasts 12 years or 25. A premium composite board over a poorly ventilated, under-flashed frame will still trap moisture, grow mold underneath, and stress fasteners early. A mid-range board over a correctly built frame will outperform it.
What a correct substructure includes
- Joist tape or a moisture barrier on top of every joist, not just at the ledger
- Proper ledger flashing where the deck meets the house, sealed against wind-driven rain
- Adequate slope away from the house — typically a slight pitch so water sheets off rather than pooling
- Joist spacing matched to the specific composite board's span rating (this varies by brand and board profile, not universal)
- Ventilation gaps at the perimeter so air can move under the deck and dry out the framing after rain
- Corrosion-resistant fasteners and hardware rated for coastal/high-moisture exposure
Skipping any one of these doesn't show up as a problem in year one. It shows up in year five or six as soft spots, fastener pop, or a musty smell coming from underneath the deck — by which point it's a tear-off, not a repair.
Composite vs. Wood vs. PVC: An Honest Comparison for This Area
There's no universally "best" decking material — there's the right material for a given budget, maintenance appetite, and exposure. Here's how the common options stack up specifically against Kendall's moss-and-moisture conditions.
| Factor | Pressure-Treated Wood | Composite | PVC / Capped Polymer |
|---|---|---|---|
| Moisture absorption | High — swells, checks, and rots without upkeep | Low — capped boards resist water intrusion | Essentially none |
| Moss/algae resistance | Poor — organic surface feeds growth | Good on capped boards; uncapped composite is more vulnerable | Very good — non-porous surface |
| Maintenance | Annual sealing/staining, mold treatment | Periodic washing, minimal sealing | Washing only, no sealing |
| Upfront cost | Lowest | Mid-range | Highest |
| Typical lifespan here | 10-15 years with real upkeep | 20-30 years | 25-30+ years |
| Feel underfoot in wet weather | Can be slick when mossy | Textured surfaces grip well when kept clean | Textured surfaces grip well when kept clean |
We install composite for most Kendall homeowners because it hits the balance point: far less maintenance than wood, meaningfully better moisture and moss resistance, at a cost that doesn't jump all the way to full PVC systems. We'll walk through PVC as an option too if low-maintenance is the top priority and budget allows — it's a legitimate upgrade, not a product we discourage.
What a Correct Composite Deck Build Involves
1. Site and Drainage Assessment
Before any framing goes in, we look at how water moves across the lot and off the house at that specific location — grading, downspout discharge points, and existing shade patterns that will affect how fast the deck dries after rain. This is the step that gets skipped most often on rushed jobs, and it's the one that causes the most callbacks.
2. Ledger and Flashing Work
Where the deck attaches to the house is the single highest-risk moisture point on the whole structure, especially with wind-driven rain coming off the Strait. We flash this connection properly and confirm it ties into the existing siding drainage plane rather than sitting on top of it.
3. Framing to Span and Fastener Spec
Joist spacing and hardware get matched to the manufacturer's span tables for the specific composite board chosen — this isn't a universal number, and using standard 16-inch spacing regardless of board type is a common shortcut that leads to bounce and premature wear.
4. Board Installation with Correct Gapping
Composite boards need consistent expansion gaps between boards and around fixed objects (posts, house walls). Gap it wrong and boards will either buckle in summer heat or leave gaps too wide in cold weather. This is also where hidden fastener systems get set — done right, no face screws are visible and the surface stays clean.
5. Railing, Stairs, and Edge Details
Fascia boards, stair stringers, and railing posts all need the same moisture attention as the deck field. These are the components most exposed to driving rain, and they're often where we see the worst deterioration on older decks in this area.
Maintenance Kendall Homeowners Actually Need to Do
One of the real advantages of composite is how little maintenance it needs compared to wood — but "little" isn't "none," especially with moss pressure this high.
- Rinse or soft-wash the deck surface at least once or twice a year, more often in shaded areas prone to moss
- Keep gutters and downspouts clear so water isn't dumping directly onto or near the deck
- Sweep debris out of drainage gaps between boards so water keeps moving through
- Check railing and stair connections annually for looseness — a sign moisture has reached a fastener
- Trim back vegetation that's shading the deck and slowing drying time
Why Hiring a Crew That Already Works Kendall Matters
A lot of decking problems we get called to repair weren't caused by bad composite board — they were caused by a crew that built the frame the same way they would in a drier climate, without accounting for how much moisture Whatcom County actually pushes at a structure over a year. Knowing the local moss cycle, the direction wind-driven rain typically comes from, and how freeze-thaw plays out at this elevation changes real decisions: joist tape placement, fastener choice, ventilation gap sizing, and where extra flashing attention goes. That's not something a spec sheet teaches — it's something you learn by building and repairing decks in this specific area.
We're a Ferndale-based crew that works Kendall regularly, so we're not guessing at local conditions or treating this as a one-off job outside our normal service area.
Signs an Existing Deck Needs Attention Before It Becomes a Bigger Job
- Persistent moss or dark staining that returns quickly after cleaning
- Soft or springy spots underfoot, especially near the house connection
- Visible gaps opening up at the ledger flashing
- Fastener heads backing out or rust staining around hardware
- A musty smell coming from underneath the deck after rain
Any of these are worth a look before they turn into a full rebuild rather than a repair or refresh.
Get a Straight Answer for Your Kendall Property
Every lot in Kendall drains a little differently, and every existing deck has its own history of moisture exposure. If you're planning a new composite deck or want an honest read on whether an existing one is holding up the way it should, we're happy to take a look and give you a straightforward estimate — no pressure, no upsell. The form below gets you started.