Orcas Island Siding Decking Built for Shaw Island's Marine Climate
Shaw Island homes sit close to the water almost everywhere you go, and that proximity shapes what a deck has to survive out here. Salt-laden air drifts in off the water and settles on every exposed surface, driving rain comes in sideways during the fall and winter storm cycle, and the shaded, damp conditions common across San Juan County give moss and algae months at a time to take hold. A deck built without that reality in mind will show it within a season or two — soft spots, green film, corroding hardware, and boards that cup or crack.
We've built and repaired decks across the San Juan Islands long enough to know which details matter here and which ones are just cosmetic. This page covers what a composite deck actually needs to hold up on Shaw Island, what our installation process looks like, and what it costs to do right.
Why Composite Decking Makes Sense in a Salt-Air Climate
Wood decking isn't a bad product, but it asks a lot of a homeowner in this climate: yearly cleaning, periodic sealing, and constant vigilance against rot in the spots that never fully dry out. Composite decking, when it's a genuine capped product installed correctly, holds up to salt air and standing moisture far better than untreated or even pressure-treated wood, because the board itself isn't feeding on moisture the way wood fiber does.
That said, composite isn't maintenance-free, and we won't tell you otherwise. It still needs to be kept clear of debris, it can still grow a film of algae in shaded, damp corners, and cheaper uncapped composite can absorb moisture at cut edges over time. The difference is that a well-built composite deck gives you a much longer runway before any of that becomes a structural problem.
Composite vs. Wood vs. PVC
| Material | Moisture Behavior | Maintenance | Typical Lifespan Here |
|---|---|---|---|
| Untreated/pressure-treated wood | Absorbs water, prone to rot in shaded/damp spots | Annual cleaning and sealing | 10–15 years |
| Capped composite | Resists moisture absorption; core is protected by a plastic shell | Periodic washing, clear drainage gaps | 25+ years |
| Uncapped composite | Can absorb moisture at cut/exposed edges | More frequent cleaning, edge sealing at cuts | 15–20 years |
| PVC (cellular) | Fully moisture-resistant, no wood fiber content | Occasional washing | 25–30 years |
We generally steer homeowners toward capped composite or PVC for anything close to the water. That's a matter of matching the product to the exposure, not a knock on wood — wood decking still has a place on more sheltered, inland sites.
What a Correct Composite Deck Installation Involves
Composite boards are only as good as what's underneath them and holding them together. Most of the decking failures we get called out to fix on the islands aren't a problem with the board itself — they're a substructure or fastening mistake that the composite surface hid for a few years before it caught up.
Substructure and Fasteners
In a salt-air environment, hardware corrodes faster than it does inland. We use stainless steel or coated, corrosion-rated fasteners and hidden fastener clip systems rated for coastal exposure, and we avoid mixing incompatible metals that can react with each other over time. Joists get protected with joist tape before boards go down, which keeps water from sitting directly on cut lumber and starting rot from underneath — the one place a deck can fail without ever showing it on the surface.
Drainage and Airflow
A deck that can't shed water and dry out underneath will hold moisture against the framing no matter what material sits on top. We set proper board spacing for drainage, keep the structure high enough off grade for airflow, and grade the ground or add drainage where a deck sits low or close to soil that holds water — a common issue on shaded island lots.
Flashing Where the Deck Meets the House
The ledger board connection is where a driving-rain climate does the most damage if it isn't flashed correctly. We install proper ledger flashing and a water-resistant barrier at that joint so wind-driven rain off the water doesn't work its way behind the siding and into the framing — a slow leak here can go unnoticed for years and cause real damage to the house itself, not just the deck.
Our Process for a Shaw Island Project
Building on an island adds a logistics layer that mainland jobs don't have, and it's worth being upfront about how we handle it.
- Site visit and assessment. We walk the existing deck or build site, check the substructure and grade, and talk through material options based on sun, shade, and water exposure on your specific lot.
- Written estimate and material plan. You get a clear scope, product selection, and cost breakdown before anything is scheduled.
- Scheduling around ferry logistics. We plan crew time and material delivery around the ferry schedule so the job runs in efficient blocks rather than stop-and-start trips, and we order materials with enough lead time to avoid delays waiting on a sailing.
- Demo and substructure work. Old decking comes out, framing is inspected and repaired or replaced as needed, and any drainage or flashing issues get corrected before new decking goes down.
- Composite installation. Boards, hidden fasteners, and railing go in to manufacturer spec, with attention to expansion gaps and drainage.
- Final walkthrough. We go over the finished deck with you, including basic care specific to your site's sun and shade pattern.
Composite Decking Cost Factors
Every deck project is different, but the same handful of factors drive the cost on most Shaw Island jobs:
| Factor | Why It Matters |
|---|---|
| Deck size and shape | More linear footage of board and railing, more cutting on complex layouts |
| Substructure condition | Existing framing that needs repair or replacement adds labor before decking even starts |
| Board tier | Capped composite and PVC cost more upfront than uncapped composite, but need less upkeep |
| Railing and fascia | Composite or metal railing systems add cost versus basic wood rail |
| Site access | Ferry scheduling and material delivery to the island affect logistics and timeline |
| Height and stairs | Elevated decks and multi-level stairs add framing and railing complexity |
We don't quote a number without seeing the site — a straightforward ground-level rebuild and an elevated deck with multiple stair runs are very different projects, and any broad price range without that context isn't useful to you.
Maintaining Your Deck Through the Moss Season
San Juan County's long wet season gives moss and algae a real head start on any exterior surface, decks included. Composite decking resists staining and growth better than wood, but shaded or low-airflow areas still need attention.
- Sweep debris off the deck regularly — wet leaves and needles trapped in gaps hold moisture against the boards and feed algae growth.
- Wash the deck surface with a soft brush and mild soap a couple of times a year, more often in shaded areas.
- Keep drainage gaps between boards clear so water can pass through instead of sitting on the surface.
- Avoid high-pressure power washing directly on composite boards, which can damage the cap layer on some products.
- Check fastener heads and railing hardware periodically for early signs of corrosion, especially on decks facing open water.
- Trim back overhanging branches where possible to cut down on shade and debris buildup.
Why Hire a Crew That Already Works Shaw Island
Getting a crew and a full load of decking material to Shaw Island isn't the same as pulling up to a job on the mainland. It takes ferry planning, realistic scheduling, and a contractor who treats island logistics as a normal part of the job rather than a surprise that shows up mid-project. We already build that into how we bid and schedule work out here.
There's also site-specific knowledge that comes from working San Juan County regularly: which exposures take the worst of the salt spray and driving rain, where moss builds up fastest on a given lot, and how local permitting works for deck projects in the county. A crew seeing an island property for the first time is often learning those things on your job. We'd rather already know them going in.
A Quick Checklist Before You Hire
Whether you go with us or someone else, these are worth confirming before work starts on a Shaw Island deck:
- Are fasteners and hardware rated for coastal/marine exposure?
- Is the ledger board properly flashed where the deck meets the house?
- Is there adequate drainage and airflow beneath the structure?
- Is the composite product capped, and does it carry a manufacturer warranty?
- Does the contractor have a realistic plan for getting crew and material to the island?
- Is the scope and cost breakdown in writing before work begins?
If you're weighing a new deck or a rebuild on Shaw Island, we're happy to take a look and walk you through what your specific site needs — no pressure, no obligation. Fill out the form below and we'll get in touch to schedule a free estimate.