Lynden Composite Decking in Kendall: Built for the Weather You Actually Get
Kendall sits in the part of Whatcom County where the rain doesn't just fall, it lingers. Between the marine-influenced weather that moves in off the water and the long stretch of gray months where moss and algae get a real foothold on any horizontal wood surface, a deck out here works harder than the same deck would in a drier climate. Composite decking earns its keep in this environment, but only when it's installed with that climate in mind — not just nailed down the way a catalog diagram shows it.
We've built and repaired decks all over the Lynden area, including out toward Kendall, and the failures we get called out to fix almost never come from bad composite boards. They come from decks that were built like they were going in a dry climate: no airflow underneath, fasteners that weren't rated for constant moisture, or a substructure that was never given a chance to drain and dry between storms. This page covers what a composite deck actually needs to hold up here, and what our process looks like when we build one.
Why the Local Climate Changes the Job
Composite decking was developed partly to solve the problems homeowners have with wood decks — splintering, staining, the annual sanding-and-sealing cycle. It does solve those. But composite isn't immune to what a wet, moss-prone climate does to a deck; it just fails differently if the install is wrong.
Driving Rain and Standing Water
When rain comes in sideways, water gets pushed under railings, into board gaps, and against the house at the ledger connection. If that water has nowhere to go, it sits. Composite boards themselves won't rot from sitting water, but the framing underneath them will, and trapped moisture is exactly what moss, algae, and mildew need to take hold on the board surface.
The Long Moss Season
Whatcom County's moss season isn't a few weeks — it's most of the year in shaded, low-airflow spots. Composite boards resist moss better than untreated wood, but a deck built tight to the ground, under trees, or without gaps for airflow will still grow a green film on the low side or in permanently shaded corners. Board choice and airflow both matter here, not just board choice alone.
Freeze-Thaw and Expansion
Our winters aren't brutal, but we do get enough freeze-thaw cycling that gaps and fastening need to account for seasonal movement. Composite expands and contracts with temperature more than people expect, and boards installed without the manufacturer's gap spec will buckle, cup, or push against fascia and posts within a couple of years.
What Correct Composite Decking Actually Involves
A composite deck is really two systems: the substructure (posts, beams, joists) and the decking surface itself. Most of what determines whether the deck lasts happens in the part you'll never see once the boards are down.
Substructure First
- Pressure-treated joists and beams rated for ground contact where applicable, with joist tape over the top edge to keep fasteners from creating a moisture entry point
- Proper joist spacing for the specific composite product — composite typically needs tighter spacing than wood, and it varies by brand and board profile
- Positive drainage slope away from the house so water doesn't pool against the ledger board
- Flashing at the ledger connection that actually sheds water past the house wrap, not just a bead of caulk
- Adequate ground clearance and airflow underneath, especially important on lower decks or decks built close to grade
Hardware That Matches the Climate
This is where we see the most corner-cutting from other jobs. In a climate this damp, standard fasteners corrode faster than people expect, and corroding fasteners stain composite boards and eventually fail structurally. We use corrosion-resistant, coated fasteners and hidden fastener clip systems rated for exterior, high-moisture use — not whatever was cheapest at the box store that week.
Board Layout and Spacing
Board gaps aren't just cosmetic. They're sized to let water drain through rather than pool on the surface, and to allow the seasonal expansion composite boards go through without buckling. Getting this wrong is one of the most common causes of the "waves" people see in a few-year-old composite deck.
Choosing a Composite Product
Not all composite decking behaves the same way in a wet climate, and this is a place where we'll give you our honest read rather than just install whatever's cheapest.
| Board Type | How It Handles Moisture | Maintenance | Typical Trade-off |
|---|---|---|---|
| Capped composite (full wrap) | Best moisture and moss resistance; core is fully sealed | Occasional wash-down | Higher upfront cost |
| Capped composite (top/sides only) | Good on visible faces; exposed cut ends need sealing | Low, but check cut ends yearly | Cut ends need attention during install |
| Uncapped composite | More prone to moisture absorption and surface mold over time | Higher — periodic cleaning to prevent staining | Lower cost, shorter practical lifespan here |
| PVC decking | Excellent moisture resistance, doesn't absorb water | Low | More expansion/contraction to plan for; different look/feel than wood-composite blends |
For most Kendall-area homes, we steer people toward fully capped composite or PVC because of how much of the year this ground stays damp. Uncapped composite isn't a bad product, it's just a product that asks more of the homeowner in a climate that doesn't give you many dry stretches to keep up with cleaning.
Color and Board Choice Matter Here Too
Darker composite boards show less algae discoloration short-term but absorb more heat and expand more through temperature swings. Lighter boards run cooler and move less, but show green or black staining sooner if airflow underneath is poor. Neither is wrong — it's a trade-off we'll walk through based on where the deck sits on your property, how much sun and shade it gets, and how close it is to trees or fencing that hold moisture in.
Our Process for a Kendall Composite Deck
- On-site assessment: we look at drainage, sun/shade exposure, proximity to trees, existing structure condition, and how water currently moves across the site
- Substructure evaluation or build: if you have an existing deck frame, we check it for rot, proper spacing, and code compliance before deciding whether to reuse or rebuild it — reusing a bad frame under new composite boards just hides the problem, it doesn't fix it
- Ledger and flashing work: done correctly at the house connection, since this is the single most common point of hidden water damage on any deck
- Framing to spec: joist spacing and blocking set to the manufacturer's requirements for the specific board profile you've chosen
- Decking installation: hidden fastener systems where the product supports it, correct gapping for drainage and expansion, and attention to cut-end sealing on capped boards
- Railing, stairs, and trim: matched to the deck board system and installed with the same drainage and fastener standards
- Final walkthrough: we go over basic seasonal maintenance with you — it's minimal compared to wood, but not zero
What to Ask Before You Hire Anyone for This
- Do they check and correct joist spacing for your specific composite product, or just build to a generic spacing?
- What fastener system are they using, and is it rated for coastal or high-moisture exterior use?
- How do they handle ledger board flashing at the house connection?
- Do they slope the substructure for drainage, or just lay boards flat?
- What's their plan for airflow underneath the deck if it sits low to the ground?
- Are they familiar with local permitting requirements for deck height, railing, and setbacks?
Why Local Experience on This Specific Job Matters
Composite decking install instructions read the same whether the deck is going in Arizona or here. What doesn't transfer is knowing how much water this ground sees in a normal winter, which yards around Kendall hold moisture longer because of tree cover or low grading, and how fast moss actually establishes itself on a shaded deck corner if airflow wasn't planned for. That's the part of the job that comes from having built and repaired decks in this specific part of Whatcom County, not from a spec sheet.
We also see the flip side of this regularly — decks built by out-of-area crews that looked fine the first summer and started showing soft spots, staining, or board movement within two or three wet seasons. Fixing that after the fact almost always costs more than building it right the first time.
Maintenance: What a Composite Deck Still Needs Here
Composite decking cuts maintenance dramatically compared to wood, but "low maintenance" isn't "no maintenance" in a climate like ours.
- Periodic wash-down to keep pollen, needles, and organic debris from feeding moss and algae growth
- Keeping gutters and downspouts clear so runoff isn't dumping directly onto or under the deck
- Trimming back vegetation that shades and holds moisture against low or ground-level decks
- Checking railing posts and fastener points annually for any early corrosion staining
- Clearing debris from board gaps so drainage paths stay open
Getting an Estimate
If you're weighing a new composite deck or replacing an aging one out in the Kendall area, we're happy to come take a look, walk the site with you, and talk through board options and what your specific yard needs for drainage and airflow. There's no pressure and no cost to get our read on it — just fill out the form below and we'll set up a time to come out.