Lynden Siding Composite Decking Built for Custer's Coastal Climate
Custer sits close enough to the water that homes here deal with a different set of conditions than decks built twenty miles inland in Bellingham or Lynden proper. Salt-laden air off the Strait, driving rain that comes in sideways during winter storms, and a moss season that can run from October through April all put real stress on an outdoor deck. A composite deck installed here needs to be built with that specific exposure in mind, not just assembled from a generic plan pulled off a truck.
We install composite decking throughout Whatcom County, and Custer's mix of open, wind-exposed lots and tree-shaded properties near the water means we see both ends of the moisture problem: decks that dry out fast but take a beating from blown rain, and decks tucked under conifers that barely dry out at all between storms. Both situations call for the same starting point — a substructure and drainage plan that assumes the deck will be wet more often than it's dry for half the year.
What Custer's Climate Actually Does to a Deck
Salt Air and Fasteners
Homes closer to the water take on a steady dose of salt in the air, even without direct ocean spray. Salt accelerates corrosion on anything metal — screws, joist hangers, flashing, railing brackets. On a wood deck this shows up as rust streaks and eventually failed fasteners. On a composite deck, the boards themselves shrug off salt exposure, but the fasteners and structural hardware underneath don't get a pass just because the surface is composite.
Driving Rain and Water Intrusion
Whatcom County storms don't always fall straight down. Wind-driven rain gets pushed under rail caps, behind fascia boards, and into any gap where flashing was skipped or done loose. Composite boards are effectively waterproof, but the framing, ledger board, and any wood trim around the deck are not — and that's where rot actually starts on a "composite" deck that was installed carelessly.
Moss and Algae Growth
Custer's long wet season, especially on shaded or north-facing decks, creates ideal conditions for moss and algae to establish on any surface that stays damp. Composite decking resists rot, but it isn't immune to surface growth — moss and green algae film will grow on composite just as readily as on wood if the deck doesn't get airflow and periodic light cleaning. The difference is that composite doesn't degrade structurally from it the way wood does; it's a cosmetic and slip-hazard issue rather than a rot issue.
Why Composite Makes Sense for This Area
We recommend composite decking to a lot of Custer homeowners specifically because of the climate factors above. It's not that wood decking can't be built well here — it can — but composite removes several of the maintenance burdens that this particular climate makes worse than average:
- No annual staining or sealing to keep ahead of moss and moisture staining
- No soft spots or splintering from repeated wet/dry cycling over a long rainy season
- Consistent color and surface texture that doesn't gray unevenly under shade versus sun exposure on the same deck
- Better resistance to the surface mildew that shows up fast on shaded, moisture-heavy lots
That said, composite is not maintenance-free — it's maintenance-different. It still needs periodic washing to keep pollen, moss spores, and organic debris from building up in the board grain, especially in a wet climate like this one.
What a Correct Composite Deck Build Involves
Substructure First
The framing underneath a composite deck matters more in this climate than in a dry one. We build to spacing and joist requirements suited to Whatcom County's moisture load, not the bare minimum spacing some composite manufacturers list for dry-climate installs. Tighter joist spacing reduces board flex and deflection over time, which matters when boards are cycling between saturated and dry through a long wet season.
Flashing and Ledger Attachment
Where the deck attaches to the house is the single most common failure point we find on existing decks, composite or wood. Proper ledger flashing that directs water away from the band joist and wall sheathing is non-negotiable on a coastal-adjacent property like this. We flash every ledger connection correctly rather than relying on caulk as a substitute for actual flashing.
Hidden Fastener Systems and Corrosion-Resistant Hardware
Given the salt air exposure, we use stainless or coated corrosion-resistant fasteners and hardware throughout the structure, not just at the visible surface. Joist hangers, structural screws, and any exposed brackets get the same corrosion consideration as the decking itself — a composite deck is only as durable as the metal holding it together.
Drainage and Airflow Underneath
We build in enough clearance and slope for water to actually drain away from under the deck rather than pooling against footings or framing. On shaded Custer lots where things dry slowly, airflow underneath the deck is one of the biggest factors in how long the substructure lasts, regardless of what the surface decking is made of.
Composite vs. Wood Decking for This Property Type
| Factor | Composite Decking | Wood Decking |
|---|---|---|
| Moss & algae resistance | Surface growth possible, but no structural damage | Growth accelerates rot in wet, shaded areas |
| Salt air exposure | Board material unaffected; hardware still needs protection | Fasteners and wood both vulnerable to salt-driven wear |
| Annual maintenance | Periodic wash, no staining or sealing | Annual or biannual staining/sealing to prevent moisture damage |
| Upfront cost | Higher material cost | Lower material cost |
| Long-term cost (10+ years) | Lower, due to reduced maintenance and replacement | Higher, from repeated maintenance and board replacement |
| Appearance over time | Consistent color; some fading possible depending on product | Requires upkeep to avoid graying, splintering, and staining |
Our Process for a Custer Composite Deck Project
- On-site assessment. We look at sun and shade exposure, drainage on the lot, existing structure condition if this is a replacement, and how close the property sits to prevailing wind and moisture patterns.
- Design and layout. Board direction, framing spacing, and railing choice are worked out based on the specific lot, not a one-size template.
- Honest estimate. You get a clear written estimate covering materials, labor, and any structural work needed — no vague allowances that turn into surprise add-ons mid-project.
- Demo and structural prep. If replacing an old deck, we check ledger, footings, and framing condition before building on top of anything questionable.
- Framing and flashing. Corrosion-resistant hardware, correct joist spacing, and proper ledger flashing go in before a single composite board is placed.
- Composite board installation. Hidden fastener systems where the product allows, consistent gapping for expansion and drainage, and clean edge and stair detailing.
- Railing and finishing details. Rail caps, post sleeves, fascia, and any lighting or stair work completed to match the rest of the build.
- Final walkthrough. We go over the finished deck with you, including basic care guidance for this specific climate.
Choosing a Deck Material Grade
Composite decking isn't one product — it ranges from capped polymer boards to lower-tier composite blends, and the difference shows up over years, not months. For a property exposed to salt air and heavy seasonal rain, we generally steer homeowners toward fully capped composite boards, where the wear layer wraps the entire board rather than just the top surface. Uncapped or partially capped boards can absorb moisture at the edges over time, which defeats much of the point of going composite in a climate like this.
We'll walk through board options, color retention differences, and warranty structures for whatever composite lines we're installing at the time — those specifics change as manufacturers update product lines, so we cover current options during your estimate rather than locking in claims here that may be outdated by the time you're ready to build.
What to Ask Before Hiring a Deck Contractor in This Area
Because moisture management is the real skill in coastal Whatcom County deck-building — not just laying boards — the contractor's approach to flashing, framing, and hardware matters more than the brand of composite on the price sheet. A few things worth checking before you hire anyone for a deck project out here:
- Do they flash the ledger board properly, or rely on sealant alone?
- What fastener and hardware grade do they use given the salt air exposure?
- Do they adjust joist spacing for a wet climate, or build to the manufacturer's dry-climate minimum?
- Are they licensed and insured for structural deck work, not just surface installation?
- Will they put the scope, materials, and price in writing before work starts?
Why a Local Crew Matters for This Job
A deck built by a crew that regularly works Whatcom County properties already knows how this climate behaves — where moss builds up first, which lot orientations dry out slowest, and how much clearance and drainage a substructure actually needs to hold up through a full wet season, not just look good on installation day. That local pattern recognition is the difference between a deck that needs re-flashing in five years and one that's still solid in twenty.
If you're planning a new composite deck or replacing an aging wood deck in Custer, we're happy to come take a look at your property and put together a straightforward estimate — no pressure, no inflated scope, just an honest read on what your deck actually needs.