Orcas Island Why Composite Decking Holds Up Better in Obstruction Pass
Obstruction Pass sits right up against the water, which means every deck out here is dealing with three things at once: salt-laden air blowing off the pass, driving rain that comes in sideways more often than straight down, and a moss season that can stretch from October well into spring. Wood decking can be made to work in this environment, but it takes constant attention — sanding, sealing, re-staining, and replacing boards that cup or split. Composite decking was built for exactly this kind of exposure. It doesn't absorb water the way wood fibers do, it doesn't feed algae and moss the way bare or weathered wood does, and it doesn't need refinishing every year or two just to keep looking presentable.
That said, "composite" isn't a single product with one set of rules. Board quality, cap technology, and — just as important — how the deck is framed and fastened underneath all determine whether a composite deck actually delivers the low-maintenance performance homeowners expect. A composite deck installed the same way you'd frame a deck in a dry inland climate will disappoint you here. One built for San Juan County's marine conditions won't.
What Salt Air, Rain, and Moss Actually Do to a Deck
It's worth being specific about the failure modes we see on Orcas Island decks, because it explains every decision in a proper installation:
Salt Air and Corrosion
Airborne salt accelerates corrosion on anything metal — screws, joist hangers, post bases, and railing hardware. Standard galvanized fasteners that would last decades inland can start showing rust streaks and weakening within a few years this close to the water. Corroding fasteners are one of the top reasons we get called out to inspect decks that are only ten or twelve years old.
Driving Rain and Water Intrusion
Wind-driven rain off the pass doesn't just fall on a deck surface — it gets pushed sideways into ledger connections, under railing posts, and into any gap where flashing was skipped or done poorly. Composite boards themselves shed water fine, but the framing, ledger board, and any wall connection underneath still need to be flashed and sealed like it's going to get hit hard, because it will.
Moss and Organic Growth
San Juan County's long, damp shoulder seasons give moss and algae plenty of time to establish, especially on decks that sit in shade from trees or the house itself, or that don't get enough airflow underneath. Moss holds moisture against a surface, and on a deck with poor drainage or tight board spacing, that moisture has nowhere to go. Capped composite boards resist staining and growth far better than wood or older uncapped composites, but board spacing, slope, and under-deck ventilation still matter for keeping moss from taking hold at the edges and in shaded corners.
Composite vs. Wood Decking: A Straight Comparison
| Factor | Cedar / Pressure-Treated Wood | Capped Composite |
|---|---|---|
| Maintenance | Annual cleaning, periodic sealing or staining | Occasional washing; no sealing or staining |
| Moisture behavior | Absorbs water, can cup, warp, or split | Resists water absorption; core stays stable |
| Moss/algae resistance | Low — bare or weathered wood is a good host surface | Higher — capped surface sheds growth more easily with cleaning |
| Fastener exposure | Standard deck screws, often visible and exposed to weather | Hidden fastener systems available, less direct salt exposure |
| Upfront cost | Lower material cost | Higher material cost |
| Lifespan in this climate | Shorter without diligent upkeep | Longer with proper installation and minimal upkeep |
| Appearance over time | Grays, weathers, can look inconsistent between boards | Color-consistent over its life, doesn't gray or splinter |
Neither option is "wrong" — some homeowners like the look of natural wood and are willing to keep up with it. But if the goal is a deck that looks the same in year eight as it did in year one with minimal upkeep, composite is the more honest recommendation for a waterfront-adjacent property like most of what's out in Obstruction Pass.
What a Correct Composite Deck Installation Involves
The decking boards get most of the attention, but they're the last piece of the puzzle. What's underneath is what determines whether the deck stays solid and dry for the long haul.
Substructure and Framing
We build the frame to handle the extra moisture load this climate puts on it — proper joist spacing for the specific composite product being used (composite boards often call for tighter joist spacing than wood, especially on angled or diagonal layouts), and joist tape or a moisture barrier on top of the framing lumber to keep water from wicking into the wood joists from repeated wetting.
Ledger and Wall Connections
Where the deck ties into the house, correct flashing is non-negotiable. This is the single most common point of hidden water damage on older decks we inspect — a ledger board that was fastened directly to the siding without proper flashing, sending water behind the wall over years. We flash this connection to shed water away from the structure, not just seal it with caulk and hope.
Drainage and Slope
A deck surface needs a slight slope away from the house so water doesn't pool or sheet back toward the wall. On composite decks, we also pay attention to board spacing and end-gapping so water can actually drain through rather than sitting on the surface — tight or improperly gapped boards trap water and speed up moss and grime buildup.
Fastening System
Hidden fastener clip systems, when compatible with the board profile, give a cleaner look and reduce the number of exposed metal fasteners sitting directly in salt air. Where face-screwing is required (stair treads, picture-frame borders, some fascia), we use fasteners rated for coastal/corrosive environments, not standard-grade hardware.
Fasteners and Hardware: The Detail That Gets Skipped
This is worth its own section because it's the detail that separates a deck that lasts from one that starts showing rust bleed and loose connections within a few years. In a marine-exposure setting like Obstruction Pass, we spec:
- Stainless steel or coated fasteners rated for coastal/corrosive exposure, not standard galvanized
- Corrosion-resistant joist hangers and structural hardware at every connection point
- Composite-specific screws or approved hidden-fastener clips matched to the board manufacturer's requirements (mismatched hardware can void product warranties)
- Stainless or properly rated hardware for railing posts and any structural attachment
The cost difference between standard and coastal-rated hardware is small relative to the total project. The performance difference over a 15- to 25-year deck life is not.
Our Process for a Composite Decking Project in Obstruction Pass
We start with an on-site assessment — checking existing structure if it's a replacement, evaluating sun/shade exposure and how much moss or algae pressure the site actually gets, and confirming access for material delivery, since some Obstruction Pass properties have tighter driveways or staging areas than others. From there:
- Site and structure evaluation — assess existing framing (if replacing an old deck), grading, and drainage around the deck footprint
- Product selection — walk through board profiles, color/finish options, and fastening systems suited to the site's exposure
- Framing and flashing — build or reinforce the substructure with moisture barriers, coastal-rated hardware, and correctly flashed ledger connections
- Decking installation — install boards with correct spacing, gapping, and fastening for drainage and long-term stability
- Railing and finish details — install railings, stair components, and any fascia or picture-framing
- Final walkthrough — review drainage, board seating, and hardware with the homeowner before we call it done
Maintenance and Cost Factors to Expect
Composite decking costs more upfront than wood, but the ongoing cost and time burden is where it pays off. Broad factors that move the price on any given job:
| Factor | Why It Matters |
|---|---|
| Board profile and brand | Capped composite lines vary in price based on cap technology and warranty length |
| Deck size and layout | Diagonal patterns, curves, and picture-framing add labor and material waste |
| Substructure condition | Replacing decking over sound, well-flashed framing costs less than a full rebuild |
| Height and access | Elevated decks or difficult site access add labor time |
| Railing system | Composite or metal railing systems vary widely in cost versus basic wood rail |
We'll always give a straightforward range once we've seen the site — we don't believe in lowball quotes that turn into surprise add-ons later.
Signs an Existing Deck Needs Attention
- Soft, spongy, or discolored spots in decking boards
- Rust streaks around fasteners or hardware
- Persistent moss or slime buildup that comes back quickly after cleaning
- Gaps or staining where the deck meets the house wall
- Railing posts that feel loose or have visible movement
- Standing water on the surface after rain instead of draining off
Any of these on a wood deck usually means active moisture damage; on an older composite deck, it can point to a framing or drainage issue underneath that's worth checking before it gets worse.
Why It Matters That We Already Work Obstruction Pass
Every property on Orcas Island deals with some version of San Juan County's marine climate, but exposure varies a lot block to block depending on how close a home sits to open water, how much tree cover it has, and which direction the prevailing weather comes from. Knowing how hard a specific pocket of Obstruction Pass gets hit by salt spray and driving rain — versus a more sheltered lot a short distance away — changes real decisions: fastener spec, board spacing, how aggressively to plan for moss, and how the ledger connection needs to be flashed. A crew that's worked the island isn't guessing at any of that. We also know the practical side of building here — material delivery logistics, seasonal weather windows that make sense for outdoor construction, and coordinating around ferry schedules when timing matters.
If you're weighing a new composite deck or need to figure out whether an existing deck is worth repairing or replacing, we're happy to come take a look and give you a straightforward assessment — no pressure, no hard sell. Fill out the form below for a free estimate.