How is composite decking different from PVC decking?

Composite decking is a blend of wood fiber and plastic, often with a protective cap, giving it a more natural wood-like look and feel. PVC decking is fully synthetic with no wood content, so it resists moisture absorption completely but can look and feel a bit more plastic underfoot. Both hold up well in wet climates; the choice usually comes down to appearance preference and budget.

What should I ask a contractor before hiring them for a composite deck build?

Ask whether they use joist tape and manufacturer-rated fastening systems, how they handle drainage and gapping for our wet climate, and whether they'll pull any required permit. Also ask to see examples of decks they've built in this region specifically, since installation details that work in a dry climate don't always hold up here. A contractor who can't answer specifics about moisture management is worth being cautious about.

Do all composite decking brands offer the same warranty?

No — warranty length and what's actually covered vary significantly between manufacturers and even between product lines from the same brand. Some warranties cover staining and mold resistance specifically, which matters in a climate like ours, while others focus mainly on structural integrity. We go over the specific warranty terms for whatever board you choose before installation.

Does composite decking actually stop moss and algae from growing on it?

Capped composite resists moisture absorption better than wood, which helps, but moss and algae can still grow on the surface film of any decking material if it stays damp and shaded long enough. The advantage is that composite doesn't rot or degrade structurally from that growth the way wood can, and it's easier to clean off. Regular sweeping and occasional rinsing keep it from taking hold in the first place.

Is a covered or partially shaded deck a bad idea for composite decking in this area?

Not necessarily, but shaded and covered areas stay damp longer, so they need more attention to drainage design and occasional cleaning to prevent surface mold. We factor sun and shade exposure into the board recommendation and drainage plan during our site evaluation rather than treating every deck the same regardless of its setting.

Composite Decking in Lynden

Composite Decking Built for Lynden's Weather

Homeowners in and around Lynden deal with a specific mix of conditions: long stretches of driving rain from fall through spring, a moss and algae season that can run half the year in shaded yards, and the damp, marine-influenced air that moves through this part of Whatcom County. A deck here doesn't fail because of one bad storm — it fails slowly, from moisture that never fully dries out between rain events and organic growth that gets a foothold in board seams, fastener heads, and the gaps between boards and framing.

Composite decking exists largely to solve this problem. Unlike wood, it doesn't absorb water into the fiber itself, so it isn't prone to the swelling, splintering, and rot cycle that wears out a cedar or pressure-treated deck in this climate. But composite isn't maintenance-free or install-proof — the board only performs as well as the framing, drainage, and fastening underneath it. We've built decks and replaced failed ones throughout the Lynden and Ferndale area long enough to know where those details actually matter.

What a Correct Installation Actually Involves

Most composite deck problems we get called out to fix aren't a bad board — they're a shortcut taken during the build. In a wet climate, those shortcuts show up faster than they would somewhere dry.

Framing and Structure

Composite boards are heavier than wood and move differently with temperature. Joist spacing needs to match the manufacturer's span rating for the board profile you're using, not just "what we always do." We check joist condition, spacing, and ledger attachment before any composite goes down — a composite deck installed over undersized or already-softening framing will still fail, it'll just take the framing with it while the boards look fine on top.

Joist Protection and Drainage

We run joist tape over the top of every joist and beam. It's a small material cost that stops water from sitting on end grain and fastener penetrations — the number one cause of hidden rot under decks that "shouldn't" have a moisture problem. We also make sure the deck has somewhere for water to go: proper slope away from the house, gaps at the rim, and no dead zones where leaves and moss debris can pack in and hold moisture against the structure all winter.

Fastening and Board Gapping

Composite expands and contracts with temperature more than most homeowners expect. Gapping has to account for the board's actual moisture content and the ambient temperature on install day, not a fixed number pulled from memory. Hidden fastener systems need to be the ones rated for that specific board profile — mixing systems or overdriving fasteners is a common cause of squeaking, board lift, and warranty denial down the road.

Choosing the Right Board for This Climate

Not all composite decking handles a wet, mossy Pacific Northwest yard the same way. The biggest choice is capped versus uncapped composite.

Capped composite has a plastic polymer shell wrapped around a wood-plastic core. This shell resists moisture absorption and staining, which matters a lot given how much of the year this region spends damp. It's what we recommend for the large majority of Lynden-area decks.
Uncapped composite is more affordable up front but the exposed core can absorb some moisture and is more prone to surface mold and fading over time in a climate that doesn't get much of a hard dry-out period.
Board texture matters more here than in drier climates — a heavily embossed wood-grain finish can actually trap moisture and organic film in the grooves, giving moss and algae something to grip. Flatter, tighter-grain finishes are easier to keep clean.

We don't push one manufacturer over another as a blanket rule — the right choice depends on your budget, the deck's sun exposure, and how much upkeep you actually want to do. What we won't do is install a board profile or fastening system that isn't rated for the framing and climate conditions on your property, even if it's the cheaper option, because we're the ones who get the call when it fails early.

Composite vs. Wood vs. PVC: A Straight Comparison

Material	Moisture Behavior in This Climate	Maintenance	Typical Lifespan Here
Pressure-treated wood	Absorbs and releases water; prone to cupping, splintering, and moss growth in shaded, damp spots	Annual cleaning, periodic staining/sealing	10–15 years before major repair
Cedar	Naturally rot-resistant but still absorbs moisture; graying and softening over time without upkeep	Regular sealing to hold color and resist moisture	15–20 years with consistent care
Uncapped composite	Core can absorb some surface moisture; more prone to mold film in shaded areas	Periodic scrubbing to prevent staining	20–25 years
Capped composite	Shell resists water absorption and staining, best fit for prolonged wet seasons	Occasional rinsing and soft-brush cleaning	25–30+ years, per manufacturer warranty
PVC decking	Fully synthetic, essentially no moisture absorption	Low; rinse to remove surface debris	25–30+ years

For most Lynden homeowners, capped composite hits the best balance of upfront cost, long-term durability against our rain and moss patterns, and appearance that still reads as a real deck surface rather than plastic.

Living With a Long Moss Season

Even the best composite deck needs some seasonal attention here — the difference is how forgiving that maintenance is compared to wood.

Sweep leaves and needles off the deck regularly in fall; trapped organic debris is what feeds moss and algae growth, not the board material itself.
Rinse shaded, low-airflow areas more often — north-facing decks and spots under trees stay damp longer and are where moss establishes first.
Use a soft-bristle brush and a composite-safe cleaner for seasonal deep cleaning; pressure washers can be used carefully but the wrong nozzle or distance can etch the board surface.
Keep gutters and downspouts clear so runoff isn't dumping extra water directly onto or under the deck.
Check board-to-board gaps once or twice a year to make sure debris hasn't packed in tight enough to trap moisture against the edges.

Our Process for a Lynden Composite Deck

We start with an on-site look at the existing structure or the build area, including drainage patterns, sun/shade exposure, and how the deck ties into the house. From there we walk through board options and framing needs specific to that site, not a generic package. During the build, we handle joist protection, correct fastening, and proper drainage as standard practice, not an upsell. When it's done, we walk the deck with you and explain what upkeep — if any — that specific board line needs.

Why Local Experience Matters Here

A composite deck built to a spec sheet written for a dry climate doesn't automatically perform the same way in Whatcom County. Framing details that are optional in Arizona are not optional a few miles from the water in Ferndale or out in the Lynden valley, where a deck can sit damp for days at a time in the winter. A crew that works this area regularly has already seen which board profiles hold up, which fastening systems loosen over a few wet-dry cycles, and where drainage mistakes turn into a soft joist two years later instead of ten. That experience shows up in details you won't notice until they either hold up — or don't.

Signs an Existing Deck Needs Attention

Boards that feel spongy, uneven, or have visible cupping
Persistent green or black staining that returns quickly after cleaning
Fasteners backing out or visible board movement underfoot
Gaps between boards that have closed up or widened unevenly
Any soft spot in the framing when checked from underneath

Cost Factors to Expect

Factor	Why It Affects Price
Board tier (uncapped vs. capped vs. PVC)	Material cost and expected lifespan scale together
Framing condition	Existing rot or undersized joists may need replacement before decking goes down
Deck size and shape	Cuts, picture-framing, and multiple levels add labor
Railing and fascia choices	Composite and metal railing systems vary widely in cost
Site access	Tight lots or elevated decks can increase labor time

We'll always give you the real range for your specific project rather than a number that sounds good on the phone and changes once we're on site.

If you're planning a new composite deck or dealing with one that's not holding up the way it should, we're happy to take a look and give you a straightforward, no-pressure estimate. Fill out the form below and we'll get back to you.