How is building a composite deck different from other exterior trade work like siding or roofing?

Decking sits horizontally and takes on standing water and foot traffic directly, while siding and roofing are built to shed water off a vertical or pitched surface. That means drainage, board gaps, and substructure protection matter even more on a deck than on most other exterior work, since there's nowhere for water to go but through or around the surface itself.

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

Ask how they protect the joists underneath the decking, how they handle the ledger connection to the house, and whether they inspect the existing structure before quoting a replacement. A contractor who can answer those in detail, unprompted, is a good sign; vague answers about "just installing the boards" are a warning sign.

What's the real difference between capped and uncapped composite decking?

Capped composite has a protective polymer layer wrapped around the wood-plastic core, which keeps moisture from soaking into the board itself. Uncapped or partially capped boards cost less but are more vulnerable to moisture absorption at cut ends and exposed faces, which matters more in a wet climate than a dry one.

Do composite deck boards get slippery when they're wet or covered in moss?

Any decking surface can get slippery when moss or algae builds up on top of it, and composite is no exception, though it won't develop the soft, splintering surface wood can. Regular washing before growth establishes, plus good drainage and airflow underneath, keeps this from becoming an issue.

Does a new deck in Kendall need a permit through Whatcom County?

Most new decks and significant deck rebuilds do require a permit through Whatcom County, particularly for structures attached to the house or built above a certain height. We handle that process as part of the project so it doesn't fall on the homeowner to navigate separately.

Kendall Composite Decking Built for Whatcom County Weather

Decking in Kendall Has to Answer to the Weather, Not Just the Design

Kendall sits in the part of Whatcom County where marine air off the Salish Sea, steady winter rain, and shade from mature trees all combine to keep outdoor surfaces damp for long stretches of the year. A deck out here doesn't fail because the homeowner picked an ugly color. It fails because moisture got into a spot it shouldn't have, air couldn't move underneath the boards, or the fastening system wasn't built to handle years of wet-dry cycling. Composite decking is a good answer to that problem when it's installed correctly — and a mediocre answer when it isn't.

This page is about composite decking specifically for Kendall properties: what the local climate actually does to a deck over time, what a correct installation looks like, and why it matters to work with a crew that already understands this stretch of the county rather than one applying a generic build to a non-generic environment.

What the Local Climate Actually Does to Decking

Moisture-Laden, Salt-Tinged Air

Even away from the immediate waterfront, the air moving through Whatcom County carries moisture and trace salt inland from the Salish Sea. Over years, that combination accelerates corrosion on unprotected metal fasteners and hardware, and it keeps wood-based products absorbing and releasing moisture on a near-constant cycle. Composite decking doesn't rot the way wood does, but the hardware, framing, and connection points underneath it are just as exposed as they would be under any other decking material — and that's where a lot of deck problems actually start.

Driving Rain and Standing Moisture

Lynden-area rain isn't gentle mist — it comes sideways often enough that any horizontal surface takes a direct hit. Decking that isn't pitched correctly, or that lacks gaps for water to drain through and away, holds water on top of the boards and in the structure below. That's the single biggest driver of premature deck failure in this region, regardless of what the decking surface itself is made of.

A Long Moss and Algae Season

Shade, moisture, and mild temperatures are exactly what moss and algae need, and Whatcom County gives them most of the year to work with. Any deck surface — wood, composite, or otherwise — will grow something green on it eventually if airflow and drainage aren't part of the design. Composite boards resist rot from this, but they can still become slick and stained if moss is left to establish.

Why Composite Makes Sense for This Kind of Weather

Composite decking is made from a blend of wood fiber and plastic, and in most modern boards, that core is wrapped in a protective polymer cap. That cap is what actually does the work in a climate like this — it keeps water from soaking into the board itself, which is the failure mode that ages wood decking fast around here (cupping, splintering, soft spots near fasteners). Composite won't eliminate moss or algae, and it won't make a poorly built deck last longer, but it removes one major variable: the decking material itself absorbing and holding water.

Capped vs. Uncapped Composite

Not all composite decking is built the same way. Fully capped boards (protected on all four sides) hold up better in wet climates than boards that are only capped on the top and sides, since the cut ends and bottom face are where moisture finds a way in over time. This is a real difference between product lines — brands like Trex and TimberTech offer multiple tiers, and the tier matters more in a climate like Kendall's than it would in a dry one.

Composite vs. the Alternatives, Honestly

Homeowners in Kendall usually compare composite against pressure-treated wood and, less often, PVC decking. Each has real trade-offs — none of them is a bad product, but each behaves differently once it's exposed to this climate year after year.

Material	Moisture Behavior Here	Ongoing Maintenance	Typical Lifespan (Local Conditions)
Pressure-Treated Wood	Absorbs and releases water constantly; prone to cupping, splintering, and checking	Annual cleaning, periodic sealing or staining	10–15 years before major boards need replacing
Capped Composite	Sheds surface moisture well; core stays protected if cuts and edges were sealed correctly	Periodic washing to control moss/algae; no staining or sealing	25–30+ years, manufacturer-dependent
PVC Decking	Fully synthetic, essentially immune to moisture absorption	Similar washing needs to composite	Comparable to or longer than composite, at a higher material cost

We install composite for most Kendall decks because it lands in the middle: strong moisture performance without the cost premium of full PVC, and none of the recurring sealing and staining that wood demands in a climate this wet. That said, we'll walk through the honest trade-offs for your specific project rather than push one material by default.

What a Correct Installation Actually Involves

The decking board is the part homeowners see, but it's the least likely part to cause problems if it's a reasonable product. Most deck failures we get called out to fix trace back to the structure underneath, not the boards on top.

Joist Protection and Framing

The joists a composite deck sits on are still wood in almost every case, and they need their own moisture protection — a butyl or foil joist tape over the top of every joist, correctly lapped, keeps standing water off the framing lumber. Skipping this is one of the most common shortcuts we see on decks that weren't built by a crew used to this climate.

Airflow and Drainage Underneath

A deck built low to the ground, or against a slope with poor grading, traps moist air underneath the boards with nowhere to go. That trapped humidity is exactly what accelerates rot in the framing and encourages moss on the underside of the deck itself. Correct clearance and grading matter as much as the decking material.

Fastening System

Hidden fastener systems (clips that sit in a groove on the board edge) are standard on most composite decking today, and they're worth doing right — the wrong clip spacing or fastener type can cause boards to buckle or gap unevenly as they expand and contract with temperature and moisture changes.

Ledger and House Connection

Where the deck attaches to the house, flashing has to be installed so water is directed away from the band board and siding, not funneled behind it. This connection point is one of the most common sources of hidden water damage on any deck, composite or otherwise, and it's not visible once the project is finished — which is exactly why it has to be done right the first time.

Managing Moss and Algae Long-Term

No decking material is moss-proof in this part of Whatcom County. What actually controls it is design and a bit of routine care:

Gaps between boards sized correctly so water drains through rather than sitting on the surface
Deck orientation and any nearby landscaping trimmed back so at least some direct sun and airflow reach the surface
Gutters and downspouts near the deck directed away from it, not draining onto or under it
A simple seasonal wash — plain water and a soft-bristle brush, or a composite-safe cleaner — before moss has a chance to establish
Avoiding pressure washers on composite at close range or high PSI, which can damage the cap layer over time

How We Build Composite Decks in Kendall

Our process doesn't change because a job is in Kendall versus elsewhere in the Lynden area, but the details we check are shaped by what we've seen hold up out here and what hasn't.

Site walk-through: we look at drainage, tree cover and shade patterns, existing grading, and how the deck will tie into the house before we talk materials.
Structural assessment: for a replacement deck, we check the existing framing for hidden rot or damage before building on top of it — reusing a compromised structure under new composite decking just hides the same problem for a few more years.
Material selection: we walk through board tiers and trade-offs based on your budget, sun exposure, and how much maintenance you actually want to do.
Permitting: most new or significantly rebuilt decks require a permit through Whatcom County — we handle that as part of the project rather than leaving it for the homeowner to sort out.
Build: joist protection, correct fastening, proper flashing at the house connection, and grading underneath for airflow and drainage.
Final walkthrough: we go over basic care with you before we consider the job finished — what to clean, what to leave alone, and what to watch for.

Why It Matters That We Already Work in Kendall

A deck built to a generic national spec doesn't automatically account for a shaded, damp lot with heavy tree cover, or for the reality that Whatcom County's permitting and inspection process has its own local rhythm. A crew that already works in and around Kendall has already seen how moisture moves through this kind of terrain, which grading mistakes actually cause problems here, and which shortcuts show up as callbacks two or three winters later. That local pattern recognition is worth more than it sounds like — it's the difference between a deck that needs attention in year four and one that doesn't need much of anything for two decades.

What to Look For in Any Contractor You Hire

They inspect the existing structure before quoting a replacement, not just the surface
They can explain joist protection and drainage detailing without being asked twice
They're clear about which composite tier they're proposing and why, not just a single default option
They handle or clearly explain the Whatcom County permitting step
They give you a straightforward maintenance rundown instead of implying the deck needs zero care ever

Get a Straightforward Estimate

If you're planning a new composite deck or replacing one that's showing its age, we're happy to take a look and walk you through what we're seeing — no pressure, no inflated scope. Use the form below to request a free estimate for your Kendall property.