How is composite decking different from PVC or capped polymer decking?

Composite blends wood fiber with plastic, while PVC and capped polymer boards are fully synthetic with no wood content, which generally gives them slightly better moisture resistance. Both perform far better than uncapped wood-plastic composite in a wet, salty climate. We can walk you through which option fits your budget and exposure level during a site visit.

What should I ask a contractor before hiring them for island decking work?

Ask how they handle material delivery and scheduling around the ferry, what fastener and hardware grade they use, and whether they build in ventilation under the deck rather than just laying boards over old framing. Ask for specifics on their ledger flashing approach too, since that's the most common failure point on attached decks. A contractor who can't answer these clearly hasn't done much island work.

Do all composite decking brands use the same hidden fastener system?

No — clip spacing, groove profile, and fastener type vary by brand and sometimes by product line within a brand. Mixing an incompatible clip with a board it wasn't designed for is a common cause of loose or squeaking boards on installs we've been called to fix. We match the fastener system to the exact board being installed.

Can composite decking be installed directly over an old wood deck's framing?

Sometimes, but only after a real inspection — framing that's been exposed to years of coastal moisture often has hidden rot or corroded connectors that won't show up until you start removing boards. We check joists, ledger connections, and posts before recommending whether to reuse or rebuild the substructure. Reusing bad framing under new composite decking just hides a problem instead of fixing it.

Does composite decking need to be sealed or stained like wood on Guemes Island?

No, that's one of the main advantages — capped composite doesn't need staining, sealing, or refinishing the way wood does, even with the island's rain and salt exposure. It does still need periodic cleaning to keep moss and salt residue from building up, but that's maintenance, not refinishing work. This is a big time savings over a multi-year wood deck upkeep cycle.

Composite Decking for Guemes Island Homes

Decking on Guemes Island Faces a Different Set of Problems

Guemes Island sits right in the path of salt air moving off the water, and that changes what a deck has to survive compared to a deck built a few miles inland in Anacortes proper. Salt-laden moisture works its way into fasteners, hardware, and any wood that isn't properly sealed or protected. Add Skagit County's long stretch of driving rain each fall and winter, plus a moss season that can run six months or more on shaded, north-facing lots, and you've got a decking environment that punishes shortcuts fast.

Composite decking is a good match for this climate when it's specified and installed correctly — but "composite" isn't one product, and a lot of the failures we get called out to fix on the island aren't the material's fault. They're installation problems: wrong fastener choice, no ventilation under the boards, framing that trapped moisture instead of shedding it. Get the fundamentals right and a composite deck on Guemes will genuinely outperform wood with a fraction of the upkeep. Get them wrong and you'll be fighting mold, board movement, and hardware corrosion within a couple of seasons.

What Salt Air, Rain, and Moss Actually Do to a Deck

Salt Air and Hardware

Salt doesn't just sit on the surface — it carries in fog and wind-driven moisture and settles into every joint, screw head, and joist hanger on the structure. Standard zinc-coated fasteners and connectors corrode noticeably faster out here than they would in a drier, inland yard. Over a few years that corrosion weakens the very hardware holding the deck together, even if the decking boards on top look fine.

Driving Rain and Drainage

Rain that comes in sideways, which is common on exposed Guemes lots, gets pushed under railings, into ledger connections, and behind any trim that isn't properly flashed. If the substructure doesn't have a clear path to shed that water — and stay dry between storms — you get slow rot in the framing even when the composite decking itself is impervious to it.

Moss and Shaded Ground-Level Decks

Lower decks and any deck tucked under fir or cedar cover stay damp for extended stretches, which is exactly what moss and algae need to take hold. Moss on a composite deck isn't usually a structural problem, but it's a slip hazard and it stains if left to sit, and it points to a deck that isn't getting enough air movement or sun exposure underneath and around it.

What a Correctly Built Composite Deck Needs Out Here

Corrosion-resistant fasteners and structural hardware rated for coastal/salt exposure, not standard-grade galvanized
A framing layer (posts, beams, joists) that's either naturally rot-resistant or properly treated and sealed at every cut end
Joist tape or a comparable barrier over the top of the framing to keep fastener penetrations from becoming water entry points
Real ventilation underneath the deck — enough clearance and airflow that the substructure can actually dry out between rain events
Proper slope and drainage so water sheds away from the house instead of pooling against the ledger board
Hidden fastener systems sized and spaced to the specific composite board profile, not a generic screw pattern
Capped composite boards on any deck with real sun and moisture exposure, which is most of them out here

Choosing the Right Composite Product

Not every composite board on the market is built the same way, and the differences matter more in a coastal climate than they would somewhere dry. The biggest split is between capped and uncapped composite.

Feature	Capped Composite	Uncapped Composite
Moisture resistance	Plastic cap sheds water and blocks absorption	More prone to moisture absorption over time
Mold/mildew resistance	Higher — the cap resists staining and organic growth	Lower — more susceptible in damp, shaded areas
Fading/salt exposure	Better long-term color stability	Can fade and chalk faster in coastal exposure
Upfront cost	Higher	Lower
Our recommendation for Guemes Island	Preferred for most sites	Only for fully covered, low-exposure areas

Board profile matters too. Grooved-edge boards paired with hidden fastener clips give a cleaner look and no exposed screw heads to corrode, but they need consistent spacing and the right clip for the specific board brand — mixing systems is one of the more common mistakes we see on older installs we're asked to repair.

Our Process for a Guemes Island Composite Deck

Site visit and structural assessment. We look at existing framing (if any), ledger connection, drainage path, and sun/shade exposure before quoting anything.
Framing plan built for the site. Post spacing, joist sizing, and hardware selection are matched to the deck's exposure — a shaded, low deck near the water gets different treatment than an elevated, sun-exposed one.
Ledger and flashing done first, correctly. This is the single most common failure point on decks attached to a house, and it's not something we cut corners on regardless of budget.
Joist protection and ventilation built in. Tape over joists, correct clearance underneath, and a drainage plan so water has somewhere to go.
Composite decking installed to manufacturer spec. Correct gapping for thermal movement, correct fastener system, correct starter and edge details.
Railing, stairs, and trim finished out. Hardware matched to the same coastal-grade standard as the structural fasteners.
Final walkthrough. We show you what's underneath, not just what you'll see from the top.

Working on the Island: Access and Scheduling

Guemes Island is reached by a short county ferry crossing, and that's a real factor in how a deck project gets planned — not a footnote. Material deliveries, dumpster or debris removal, and crew scheduling all have to account for ferry timing rather than treating it like a normal in-town job where a supplier can make three trips a day if something's short. We plan composite and hardware orders to arrive complete before we mobilize, sequence the crew's time on-island efficiently, and build ferry timing into the schedule we give you up front — so you're not getting surprised by delays that were predictable from day one. A crew that hasn't worked the island before often underestimates this, and it shows up as blown timelines.

Maintenance in a Salt-Air, Moss-Prone Climate

One of the real selling points of composite decking is how little it asks of you compared to wood — but "low maintenance" doesn't mean "no maintenance," especially here.

Rinse salt residue and debris off the deck surface a few times a year, more often on exposed, waterfront-facing decks
Sweep or blow off fir needles and leaf litter before they trap moisture against the boards
Clean moss and algae with a soft-bristle brush and a cleaner labeled safe for composite — pressure washing on the wrong setting can damage the cap layer
Check railing hardware and fastener heads annually for early corrosion, especially on the most exposed side of the house
Keep gutters and downspouts near the deck clear so runoff isn't dumping extra water onto or under the structure

What Drives the Cost

Factor	Why It Matters on Guemes Island
Deck size and layout	More square footage and multiple levels or angles add material and labor
Board and hardware grade	Capped composite and coastal-rated hardware cost more upfront, less in repairs
Substructure condition	Replacing failed existing framing adds cost but is not optional on a rebuild
Site access	Ferry logistics and material staging affect scheduling and delivery costs
Railing and stair complexity	Custom railing runs and multi-level stairs add labor
Height and drainage needs	Elevated decks need more engineering attention for drainage and structure

Composite decking projects here typically land somewhere in the range of a mid to upper wood deck rebuild once you account for coastal-grade hardware and a properly ventilated substructure — we'll walk you through the real numbers for your specific site rather than quoting off a generic square-footage rate.

Why It Matters That We Already Work Guemes Island

A crew that treats Guemes like any other Anacortes address tends to underbid the logistics, underspec the hardware, and skip the ventilation details that don't show up as a problem until year two or three. We've built our framing and fastener standards around what actually holds up in this specific salt-air, high-rain, moss-heavy environment — not a generic coastal spec pulled from a manufacturer brochure. That means realistic scheduling around the ferry, material orders sized correctly the first time, and a deck built to handle the conditions it's actually going to sit in.

If you're planning a new composite deck or replacing one that's showing its age, we're glad to come take a look and walk the site with you. Reach out for a free, no-pressure estimate — we'll give you a straight assessment of what your Guemes Island property needs and why.