How long does composite decking actually last compared to a wood deck?

Well-built capped composite decking generally holds up for decades with minimal upkeep, while wood decks typically need refinishing every year or two and full replacement much sooner, especially in a wet, salt-exposed climate. The gap widens the closer a property sits to open water, since that's where wood's moisture and fastener problems show up fastest. Composite costs more upfront but usually costs less over the life of the deck.

What should I ask a contractor before hiring them to build a deck near the water in Marietta?

Ask what fastener grade they use, how they handle ledger board flashing, and whether they've built decks on low-lying or waterside lots in Whatcom County before. A contractor who answers specifically, rather than in general terms, is more likely to actually understand what sustained moisture and salt exposure do to a deck. Also confirm their Washington contractor license and insurance are current.

Are all composite decking brands built to the same quality standard?

No — composite decking varies significantly between manufacturers in wood-fiber-to-plastic ratio, cap quality, and how well the product resists moisture and mildew over time. Lower-quality or uncapped boards can absorb water and grow surface mildew noticeably faster than a well-engineered capped product, especially in a shaded, damp climate like this one. We only install composite lines we've seen hold up over years in this specific climate, not just in marketing material.

What's the real difference between capped and uncapped composite decking?

Capped composite has a wood-plastic composite core wrapped in a protective plastic shell that keeps moisture and mildew from reaching the core, while uncapped composite is exposed wood-plastic blend on every side and absorbs water more readily. In a long-moss-season climate, that difference shows up as faster surface staining and mold growth on uncapped boards, particularly in shaded spots. We standardize on capped composite for that reason.

Does building a deck in Marietta require anything different from a deck elsewhere in Ferndale?

The core challenges, salt air, driving rain, and a long moss season, run across most of Whatcom County, but Marietta's closer, more direct exposure to open water can mean a steadier dose of all three than a more sheltered inland lot sees. We evaluate each site's actual exposure rather than assuming every Ferndale-area property needs identical detailing.

Composite Decking Built for Marietta's Coastal Climate

Why Decks in Marietta Wear Differently Than Most Whatcom County Yards

Marietta sits low and close to open water on the outskirts of Ferndale, which means the homes there catch a more direct dose of what Whatcom County's climate can do to an exterior structure. A deck out here isn't just dealing with rain totals on a chart — it's dealing with marine air moving across the property more directly than it would a mile or two inland, driving rain that comes in sideways as often as it falls straight down, and a moss and mildew season that can run nearly year-round on a shaded or north-facing surface. A wood deck built to a generic spec, or a composite board chosen without thinking about salt exposure, tends to show its age here faster than it would in a drier, more sheltered part of the county.

This page covers what a Marietta property actually needs from a composite deck, what a correct build involves given the local conditions, and why the details matter more here than they would on a more sheltered inland lot.

What Marietta's Climate Actually Does to a Deck

Salt Air and Corrosion

Being close to open water means Marietta properties take on a steadier dose of salt-laden air than homes set further back from the shoreline. That air works on any exposed metal — fasteners, brackets, railing hardware — and it does it continuously, not just during storms. Corrosion in a fastener often starts long before it's visible, quietly losing holding strength while the deck still looks fine from a few feet away. Fastener grade isn't a place to save money on a deck this close to the water.

Driving Rain and Moisture at the Substructure

Rain in this part of Whatcom County rarely falls straight down. Wind pushes it sideways and up under railings, ledger connections, and gaps between boards, which is a different load than a simple rainfall total suggests. That matters more for the substructure than for the visible decking — the framing underneath is what actually holds the deck up, and it's usually the first thing to suffer if drainage, flashing, or ventilation underneath the deck surface weren't handled correctly the first time.

A Long Moss and Mildew Season

Mild temperatures and near-constant moisture add up to a moss and mildew season that can stretch through most of the year across Whatcom County, and a low-lying, water-adjacent spot like Marietta gets it worse than most. Any decking surface that's even slightly porous, or that holds water against the board instead of shedding it, becomes a growth surface over time — usually starting in shaded corners and under railings well before it's obvious from the yard.

What "Composite Decking" Actually Means

Composite decking generally combines wood fiber and plastic, but the ratio, the plastic type, and how the board is finished vary quite a bit between manufacturers. Two distinctions matter most for a property exposed the way Marietta is.

Capped vs. Uncapped

Capped composite boards wrap a protective plastic shell around a wood-plastic composite core, which keeps the core from absorbing moisture and resists staining, mildew, and UV fade. Uncapped composite is the older style — the wood-plastic blend is exposed on every side, so it can soak up moisture and is more prone to surface mold and fading over time. In a climate with this much sustained rain and salt exposure, that gap in performance shows up faster than it would somewhere drier, which is why we standardize on capped composite for Marietta builds.

Composite vs. PVC Alternatives

Some manufacturers also make fully cellular PVC decking, which has no wood fiber at all. PVC resists moisture absorption completely and can be a good fit for a deck that stays wet more of the year than most, but it flexes more under heavy point loads and generally costs more than capped composite. We'll talk through whether composite or PVC makes more sense for a given deck based on sun exposure, shade, and how the space gets used — there isn't one right answer for every property.

What a Correct Composite Deck Build Involves Here

The decking boards get most of the attention, but on a property this close to the water, the substructure and fastening details are what actually determine whether the deck holds up. A build done right for Marietta conditions includes:

Framing material rated for sustained moisture exposure — pressure-treated lumber suited to ground contact and damp conditions, or an alternative substructure where the site calls for it
Stainless steel or coated corrosion-resistant fasteners throughout, not standard-grade hardware that gives out faster in salt air
Hidden fastener systems on the surface where the product allows, reducing exposed metal and giving a cleaner, moss-resistant surface
Correct board gapping for expansion, contraction, and drainage, since composite moves with temperature differently than wood
Proper ledger board flashing where the deck ties into the house — a common failure point when wind-driven rain works its way behind the connection
Joist spacing matched to the specific composite product's span rating rather than a generic wood-framing layout
Ventilation and drainage beneath the deck so moisture and organic debris don't sit against the framing and feed moss growth
Railing and post attachment sized correctly for the site, especially on any elevated or waterside section of the deck

Skip any one of those and the deck usually still looks fine on day one. The problems show up a few winters later — a soft spot in the framing, a railing post that's started to loosen, or dark staining where fasteners have begun to corrode.

How Our Process Works

We start with a site visit to look at what's actually there: existing framing condition if it's a replacement, drainage and grade around the deck area, how much shade the site gets through the day, and how directly the property faces open water. From there we walk through composite product options that fit the budget and how the space will actually be used, whether that's a quiet spot to sit or something built for entertaining.

Permitting for decks in and around Ferndale generally follows Whatcom County's building requirements, and low-lying or waterside lots can carry additional review depending on the property. We handle that as part of the job rather than leaving it for the homeowner to sort out. Once permitted, the build follows the sequence above — substructure first, with every framing and fastening decision made for the site's actual exposure, then the composite surface, railing, and any trim work. We finish with a walkthrough covering what the specific product you chose actually needs going forward, which is usually very little, but not nothing.

Composite Decking Compared to the Alternatives

Material	How It Handles Salt Air, Rain & Moss	Maintenance	Typical Lifespan Here
Capped composite	Strong — cap layer resists moisture absorption, staining, and mildew growth	Occasional washing; no sealing or staining	Long-term, backed by manufacturer warranty
Cellular PVC	Excellent — no wood fiber to absorb moisture at all	Occasional washing; no sealing or staining	Long-term, generally at a higher upfront cost
Uncapped composite	Moderate — absorbs some moisture, more prone to surface mold in shaded areas	Periodic cleaning to manage mildew and staining	Shorter than capped products in this climate
Pressure-treated wood	Weak against salt air and sustained moisture over time — fasteners corrode faster, boards cup and split	Regular sealing or staining required	Shortest, with the most ongoing upkeep
Cedar	Attractive but still needs finish upkeep against moss and moisture	Periodic sealing to slow graying and checking	Moderate if maintained closely; degrades faster if neglected

What Composite Decking Still Needs From You

Composite decking is low-maintenance compared to wood, not maintenance-free, especially in a climate that grows moss most of the year. A little routine care makes a real difference:

Rinse or wash the surface periodically to clear pollen, organic debris, and early moss growth before it takes hold in the board texture
Keep gaps between boards clear of leaves and needles so water and airflow can move through as designed
Check railing posts and hardware annually for early signs of corrosion or loosening, especially after a heavy storm season
Trim back landscaping that shades the deck or holds moisture against its edges, since shaded areas are where moss and mildew show up first
Address any substructure concerns — soft framing, standing water underneath — right away, since that's structural, not cosmetic

Why It Matters That We Already Work Marietta

A crew that mostly builds decks further inland can still install composite decking competently, but a property this close to open water has variables that don't come up as often elsewhere — more direct salt exposure, driving rain that finds its way into connection points a sheltered lot wouldn't see, and a moss season that punishes any shortcut in drainage or ventilation. Working this area regularly means we're not guessing at what actually holds up here. We know which composite lines perform well against years of Whatcom County weather rather than a few dry months, what fastener grade is worth the extra cost, and how the permitting process works for this part of the county, because we've built to these conditions before, on similar lots.

That familiarity also shows up in smaller ways — being straightforward with a Marietta homeowner about what their specific site actually needs, rather than applying the same spec sheet we'd use on a sheltered, tree-covered lot on the other side of Ferndale.

Get a Straight Answer About Your Deck

Whether you're replacing a tired wood deck, building new, or just want an honest read on what a composite deck would take on your Marietta property, we're glad to walk the site with you and lay out the options plainly. Reach out below for a free, no-pressure estimate.