How is installing composite decking different from building a traditional wood deck?

The decking material itself installs differently — most composite boards use hidden fastener systems and specific spacing tolerances rather than face-nailing or screwing like wood. The bigger difference is in the substructure and hardware, which need more attention to moisture and corrosion resistance since composite boards are only as good as the frame and fasteners underneath them.

What should I ask a contractor before hiring them for composite decking work on Lummi Island?

Ask whether they've worked on the island before and how they plan around ferry scheduling for materials and crew. Also ask what fastener and hardware standard they use for coastal, salt-air conditions, since a contractor without island experience may not think to upgrade past standard exterior-grade hardware.

Do you install specific composite decking brands, or can homeowners choose their own?

We work with several established composite decking manufacturers and help homeowners choose based on their budget, site exposure, and appearance preferences. What we don't compromise on is fastener and installation specs suited to a coastal environment, regardless of which product line is chosen.

What's the actual difference between capped and uncapped composite boards?

Uncapped composite is a wood-fiber and plastic blend all the way through, while capped composite has a polymer shell wrapped around that core. The cap makes the board more resistant to moisture absorption and generally easier to keep clean of moss and algae, which matters more in a wet coastal climate than in a dry inland one.

Does Lummi Island's ferry access change how a deck project is scheduled or priced?

Yes — material deliveries and crew days need to work around the ferry schedule, so we build that into the project timeline from the start rather than treating it as a surprise delay. It's a scheduling factor more than a major cost driver, but it's something a mainland-only contractor may not plan for properly.

Composite Decking Services in Lummi Island, WA

Composite Decking on Lummi Island: Built for a Coastal Climate

Lummi Island sits right in the path of everything Whatcom County's weather can throw at an outdoor structure: salt-laden air off the water, driving rain that comes in sideways during winter storms, and a moss season that can stretch from October well into spring. A deck out here isn't just a backyard amenity — it's an exterior surface that has to hold up to conditions most inland decks never see. Composite decking, installed correctly for this specific environment, is one of the more reliable answers to that problem. Installed wrong, it can trap moisture and grow moss just as fast as the wood it replaced.

This page covers what composite decking actually needs to perform well on Lummi Island specifically — not composite decking in general — and what our process looks like for homeowners out here.

Why Whatcom County's Coastal Climate Is Hard on Decks

Three conditions do most of the damage to decks in this area, and they compound each other:

Salt air: Airborne salt accelerates corrosion on fasteners, hidden clips, and any metal hardware in the substructure. A fastener system rated for inland use can start failing years earlier here.
Driving rain: Wind-driven rain doesn't just fall on a deck surface — it gets pushed sideways and upward into board gaps, end cuts, and ledger connections. Drainage and slope matter more here than in a sheltered yard.
Extended moss season: Cool, damp, low-sun conditions for much of the year create ideal moss and algae growth on any surface that stays wet or shaded. Board spacing, airflow underneath the deck, and surface texture all affect how much moss actually takes hold.

None of these are exotic problems, but they're persistent, and a deck built to a generic spec sheet without accounting for them tends to show its age faster on Lummi Island than it would elsewhere in the county.

What a Correct Composite Deck Installation Actually Involves

The Substructure Matters More Than the Boards

Composite boards get most of the attention, but the framing underneath does most of the work. In a salt-air environment, we pay close attention to:

Corrosion-resistant fasteners and hardware rated for coastal exposure, not just standard exterior-grade hardware
Joist tape or a comparable barrier on framing to slow moisture intrusion at fastener penetrations
Proper joist spacing for the specific composite product being installed — composite boards flex differently than wood and many products require tighter spacing, especially on angled or picture-frame layouts

Drainage and Slope

A deck surface needs a slight slope away from the house and a clear path for water to get off the surface and out from underneath. On a site with heavy driving rain, we also look at where water sheds off the roofline above and whether it lands on or near the deck, since that's extra water volume the deck wasn't necessarily designed to handle.

Ventilation Underneath

Low, tight-to-the-ground deck framing traps humid air underneath the boards, which is exactly what keeps a deck damp long after the rain has stopped — and damp is what moss needs. Where height and grading allow, we build in enough clearance and skirting airflow to let the underside dry out between storms.

Board Layout and Fastening

Hidden fastener systems give a clean surface but need to be installed to the manufacturer's exact spacing and gapping tolerances — get the board gaps wrong and you either get excessive movement or standing water in tight seams. We follow manufacturer specs for gapping rather than eyeballing it, since Whatcom County's temperature and moisture swings affect how much boards expand and contract seasonally.

Comparing Composite Decking Types for This Environment

Not all composite decking is built the same way, and the differences matter more in a wet, salty climate than they would somewhere dry. Here's how the main categories generally compare for a Lummi Island install:

Type	Moisture Behavior	Moss/Algae Resistance	Maintenance
Uncapped composite	Wood-plastic blend; can absorb some moisture at cut ends over time	Moderate — porous surface can hold onto organic growth	Occasional cleaning; end-cuts should be sealed at install
Capped composite	Polymer shell resists moisture absorption at the surface	Better — smoother, less porous cap sheds growth more easily	Lower; periodic rinse/wash keeps it looking new
Solid PVC decking	No wood content, essentially moisture-inert	Best — least hospitable surface for moss and algae	Lowest; typically just soap and water rinses

We don't push one product line over another as a blanket rule — the right choice depends on budget, the amount of shade and moisture exposure on the specific site, and how the deck will actually be used. What we won't do is install a lower-tier product with hardware or fastening that isn't suited to a coastal site, because that's where premature failures actually come from.

Our Process for Lummi Island Deck Projects

Site visit and assessment: We look at sun/shade exposure, existing drainage, wind exposure, and the condition of any structure the new deck ties into (ledger board, foundation posts).
Material selection: Based on the site conditions above, plus your budget and how you plan to use the space, we go over composite options and fastener/hardware specs suited to salt air.
Scheduling around ferry access: Since Lummi Island is reached by ferry, we plan material deliveries and crew days around the ferry schedule up front, so the project timeline you're given already accounts for it rather than getting adjusted mid-job.
Demo and substructure work: Removal of any existing deck, inspection and repair or replacement of framing, and installation of corrosion-resistant hardware and moisture barriers.
Decking installation: Boards installed to manufacturer spacing and fastening specs, with attention to drainage slope and end-cut treatment.
Final walkthrough: We go over basic maintenance for the specific product installed, since capped and uncapped composites have different care needs.

Maintenance in a Moss-Prone, Salt-Air Environment

Composite decking is lower-maintenance than wood, but "low-maintenance" isn't "no-maintenance," especially on Lummi Island. A realistic maintenance routine looks like:

Rinsing the deck surface periodically to clear salt residue and organic debris before it has a chance to establish
Sweeping leaves and needles out of board gaps in fall, since trapped organic matter is what feeds moss growth over winter
Keeping gutters and downspouts near the deck clear so runoff isn't dumping extra water onto or under the deck
Checking under-deck ventilation isn't blocked by stored items, planters, or overgrown landscaping
A occasional soft-wash with a composite-safe cleaner in early spring, before moss season fully takes hold

None of this requires the sanding, staining, and sealing that a wood deck needs — that's the actual maintenance advantage composite offers here — but skipping basic upkeep will shorten the life of even a well-installed composite deck in this climate.

Cost Factors for a Lummi Island Composite Deck

Composite decking projects vary widely based on size, product tier, and site conditions. Rather than quote a number that won't match your situation, here are the factors that actually move the price:

Factor	Why It Affects Cost
Deck size and shape	Larger footprints and angled/picture-frame layouts use more material and labor hours
Product tier (uncapped, capped, PVC)	Material cost per square foot varies significantly between tiers
Substructure condition	Existing framing that needs repair or full replacement adds labor and material
Height and access	Elevated decks or difficult site access increase labor time and may require additional structural work
Ferry logistics	Material delivery and crew transport timing is built into scheduling rather than added as a surprise fee, but it does factor into project timelines
Railing and fascia choices	Composite or metal railing systems and fascia boards add to total project cost beyond the decking surface itself

Why It Matters to Hire a Crew That Already Works on Lummi Island

A contractor based on the mainland who occasionally takes an island job will plan the same way they would for any other site — and then get surprised by ferry schedules, wind exposure on an open lot, or how much moss growth actually shows up by the following winter. A crew that regularly works Lummi Island and the rest of Whatcom County's coastal areas builds the ferry logistics, the corrosion-resistant hardware, and the drainage detailing into the plan from day one, instead of treating them as afterthoughts once a problem shows up.

That familiarity also shows up after the job is done. Knowing which composite products and fastening systems have actually held up on nearby coastal sites — and which combinations tend to need extra attention — comes from doing the work here repeatedly, not from a manufacturer's general spec sheet.

Signs Your Current Deck May Need Replacing

If you're weighing whether to repair an existing deck or replace it with composite, look for:

Soft or spongy spots in wood decking, especially near the house or at board ends
Persistent moss or algae that returns within weeks of cleaning
Rust staining around fasteners or visible corrosion on hardware
Boards that have cupped, warped, or separated from the frame
Standing water that doesn't drain within a few hours after rain stops
A substructure more than 15-20 years old that hasn't been inspected recently

Any of these are worth a look before deciding whether a repair or a full replacement makes more sense for your situation.

If you're considering composite decking for a Lummi Island property, we're happy to walk the site, talk through product options suited to salt air and rain, and give you a straightforward, no-pressure estimate. Use the form below to get started.