What's the real difference between composite and PVC decking, and does it matter for a place like Fidalgo Island?

Composite decking blends wood fiber with plastic and typically has a protective cap layer, while PVC (cellular vinyl) decking contains no wood fiber at all and absorbs essentially no moisture. In a marine climate like this one, both perform well, but PVC has a slight edge on moisture resistance while capped composite often looks and feels more like natural wood. We'll talk through which fits your budget and style rather than assuming one is automatically right.

What should I ask a contractor before they build a composite deck on my Anacortes home?

Ask how they handle ledger board flashing where the deck meets the house, since that's the most common source of long-term water damage. Ask what fastener and hardware grade they use, given how salt air here accelerates corrosion. Also confirm they're pulling the required permit and are familiar with local guardrail code, and ask for references from other decks they've built on the island.

Do you install a specific composite decking brand, or can I choose?

We work with several established composite decking manufacturers and can walk you through the options rather than pushing one brand regardless of fit. What matters most is choosing a capped composite product with a solid warranty and a color or texture that suits your home, not chasing a specific label. We'll give you honest input based on how each option tends to hold up in this climate.

Why does the gap between composite boards matter so much here?

Correct board spacing lets water drain through the deck surface instead of pooling on top of it, which matters a lot given how much rain Fidalgo Island gets. Proper gaps also allow composite boards room to expand and contract with temperature and moisture changes without buckling. Too tight, and you get standing water and stress on the boards; too wide, and you lose stability and a clean finished look.

How does Fidalgo Island's moss season affect deck maintenance compared to drier parts of Washington?

The extended damp, shaded stretch of fall through spring here gives moss and algae far more opportunity to establish than in drier inland areas of the state. Shaded or north-facing sections of a deck need more frequent rinsing and debris removal to stay ahead of it. Homes closer to tree cover or without much direct sun exposure will generally need more attention through the wet months than a deck in a fully open, sunny yard.

Composite Decking for Fidalgo Island Homes

Fidalgo Island's Marine Climate Is Hard on Decks

A deck on Fidalgo Island lives in a different environment than one thirty miles inland. Homes here sit close to the Salish Sea, and that means salt-laden air moves through the yard almost constantly. Salt air accelerates corrosion on anything metal — fasteners, brackets, railing hardware — long before it becomes an obvious problem to the eye. By the time rust stains show up on the deck surface, the hardware underneath has usually been degrading for a while.

Add in driving rain that comes sideways off the water during winter storms, and you've got a second problem: water finding its way into places a deck was never designed to handle it, especially where the deck meets the house. Then there's moss. Anacortes and the rest of Skagit County stay damp and shaded for a long stretch of the year, and moss doesn't need much encouragement to take hold on a north-facing deck or one tucked under trees. On composite boards, moss and algae aren't just cosmetic — they hold moisture against the surface and make boards slick underfoot.

None of this means composite decking is a bad choice here. It's usually the right one. But it means the build has to account for salt exposure, sustained moisture, and low sun angles in a way that a generic install manual doesn't fully cover.

What a Correct Composite Deck Build Requires in This Climate

Substructure and Framing

Composite boards are only as good as what's underneath them. On Fidalgo Island we treat the substructure — joists, beams, posts, and footings — as the part of the job that determines whether the deck lasts. That means properly rated pressure-treated framing lumber, correctly sized and spaced joists for the board span, and footings set below frost depth and bearing on solid ground, not fill.

Ledger Board and Flashing

Where a deck attaches to the house is the single most common failure point on any deck, composite or not. Wind-driven rain off the water pushes moisture toward that ledger connection harder than it would on a sheltered inland lot. A correct install uses proper flashing — metal flashing integrated with the house's water-resistive barrier, not just caulk over a ledger board — so water sheds away from the rim joist instead of soaking into it over the years.

Drainage and Airflow Underneath

Composite boards don't rot the way wood does, but the framing under them still can if it stays wet. We build in airflow beneath the deck and grade the ground below it so water doesn't pool. Joist tape over the top of each joist keeps standing water off the wood and extends the life of the frame significantly — cheap insurance against a damp Fidalgo Island winter.

Fasteners and Hardware

Given the salt air, we don't cut corners on hardware. Stainless steel or high-grade coated fasteners and structural connectors cost more up front than standard hot-dipped galvanized, but on a marine-exposed property the difference in corrosion resistance is the difference between hardware that's still solid in fifteen years and hardware that's rusting through in five.

Composite vs Other Decking Materials for This Climate

Material	Salt air & rain performance	Moss/algae resistance	Typical upkeep
Capped composite	Strong — cap layer resists moisture absorption and staining	Good, especially with textured/capped surfaces; still needs periodic cleaning in shaded spots	Occasional wash, no sealing or staining
Traditional wood (cedar or pressure-treated)	Moderate — absorbs moisture, prone to cupping and splitting near the coast	Poor without regular treatment; moss takes hold quickly on damp wood	Annual sealing/staining, regular inspection for rot
Uncapped or first-generation composite	Weaker — more prone to moisture absorption and swelling over time	Fair, but surface can hold moisture and stain more than capped boards	Periodic cleaning; more prone to fading and mildew staining
Cellular PVC	Excellent — doesn't absorb moisture at all	Good; smooth surfaces shed algae easily	Low; can look and feel less like natural wood than composite

We install capped composite as our standard recommendation for most Fidalgo Island homes. It strikes the best balance of moisture resistance, appearance, and long-term maintenance for a marine climate, without the added cost premium of full PVC systems. That said, we'll walk through the trade-offs honestly rather than push one product regardless of the situation.

Our Process for a Fidalgo Island Composite Deck

On-site evaluation — we look at sun exposure, wind direction, drainage, and how close the site is to salt water, since all of that shapes the build.
Tear-off, if replacing an existing deck — including a check of the ledger and framing for hidden rot before anything new goes up.
Framing and structural work — footings, posts, beams, and joists sized correctly for the deck's footprint and load.
Flashing and waterproofing at the house connection — the step most likely to get skipped elsewhere and the one we treat as non-negotiable.
Composite board installation — hidden fasteners, correct board spacing for drainage and expansion, and attention to picture-framing and pattern where it's part of the design.
Railings and finish work — composite, cable, or glass rail systems installed to code for the deck's height.
Final walkthrough — we go over basic care so you know what to expect through your first wet season.

Cost Factors for a Composite Decking Project

Factor	How it affects the price
Deck size and footprint	Larger square footage means more boards, framing, and labor hours
Height off grade	Taller decks need more substantial footings, posts, and code-required guardrails
Condition of the existing structure	Reusing sound framing costs less than full tear-off and rebuild
Board tier	Entry-level capped composite vs premium composite or PVC changes material cost per square foot
Railing style	Composite rail runs less than cable or glass systems
Site access	Tight side yards or elevated lots can slow material handling and add labor time
Permit and engineering needs	Taller or more complex decks may require stamped engineering, which adds cost and lead time

We give a written estimate that breaks these out so you can see where the money is going, rather than a single lump number.

Moss, Algae, and Mildew: What Ongoing Care Actually Looks Like

Capped composite needs far less upkeep than wood, but "low maintenance" doesn't mean "no maintenance" on Fidalgo Island. A little seasonal attention keeps a deck looking and performing the way it should through the wet months.

Sweep off leaves, needles, and debris regularly — trapped organic matter is what feeds moss and algae growth
Rinse the deck with a garden hose or low-pressure washer setting a few times a year, more often in shaded areas
Avoid high-pressure washing directly on composite boards, which can damage the cap layer over time
Clean out the gaps between boards where debris and grit tend to collect
Trim back overhanging branches or shrubs to let more light and airflow reach shaded sections
Check railing hardware and fasteners annually for early signs of corrosion, especially closer to the water
Address standing water or poor drainage under the deck before it becomes a framing issue

Permits and Railing Requirements to Know About

Most deck projects in Anacortes and unincorporated Skagit County that involve structural changes, height above a certain threshold, or attachment to the house require a building permit, and decks above a certain elevation need code-compliant guardrails with specific height and baluster spacing requirements. Exact thresholds depend on the jurisdiction and the specifics of your site, so we handle the permit application and inspection process as part of the job rather than leaving it to the homeowner to sort out. Getting this wrong doesn't just risk a failed inspection — it can create real safety and resale issues down the line.

Why a Crew That Already Works Fidalgo Island Matters

A lot of what makes a deck last here isn't in a manufacturer's install guide — it's knowing how a given lot sits relative to wind and water, which older Fidalgo Island homes tend to have framing quirks from past additions, and which local inspectors want to see on a permit set before they'll sign off. A crew that works this area regularly has already seen how salt air, moss, and driving rain play out on real decks over real winters, not just in a training manual. That local pattern recognition is what keeps a deck from becoming a five-year problem instead of a twenty-year investment.

If you're weighing a new composite deck or a replacement for one that's showing its age, we're happy to take a look and talk through what makes sense for your property. Fill out the form below for a free, no-pressure estimate.