Seattle gets over 38 inches of rain per year, spread across roughly 150 rainy days. That's not the monsoon rains of Houston or the brief afternoon thunderstorms of Denver — it's a sustained, persistent wet climate that doesn't give wood a real chance to dry between rain events. When you're choosing between composite and cedar decking, climate performance is the most important variable. Here's what 15 years of building decks in King County has taught us.

Seattle's Rain Problem

The challenge with wood decks in the Pacific Northwest isn't any single rainstorm — it's the cumulative effect of constant moisture cycling. Wood absorbs water when it's wet and dries when conditions allow. In most of the country, summers are hot and dry enough that wood decks get a genuine drying season. In Seattle, that drying window is shorter and less reliable. The result: wood decks here experience more moisture cycles per year than in most US climates, accelerating the natural processes of warping, checking, and biological growth.

This matters for your material decision because some materials handle moisture cycling well and some don't. Cedar performs reasonably well with active maintenance. Composite performs excellently with essentially no maintenance — but only if you buy the right type.

Cedar Decking: The Real Story

Cedar has been the go-to choice for PNW decks for generations, and it earns that reputation for real reasons. Western Red Cedar contains natural extractives — tannins and phenols — that resist fungal decay and insect damage better than most softwoods. It's workable, beautiful, holds fasteners well, and produces a warm, natural aesthetic that many homeowners love. There is no composite product that exactly replicates the character of a freshly milled cedar board.

But cedar is not a maintenance-free material in Seattle's climate, and it has never been.

The Maintenance Reality

Left unsealed in Seattle's wet climate, cedar begins to gray within one season and develops surface checking within two to three years. Gray is purely cosmetic — some homeowners prefer the driftwood-silver patina that develops naturally. Checking — surface cracks that run along the grain — is a structural precursor to more serious breakdown.

To maintain cedar's appearance and integrity, you need to clean and re-seal or re-stain the deck every one to two years. Using a quality oil-based penetrating stain costs $300–$600 in materials for a 300-square-foot deck, plus labor if you hire it out. Do it yourself, and that's a full weekend of work every year or two. Over 20 years, that maintenance adds $6,000–$15,000 to the true cost of a cedar deck depending on whether you hire out the labor.

When you add the 20-year maintenance cost to the initial build cost, cedar frequently ends up costing more than composite — despite composite's higher upfront price.

When Cedar Is the Right Call

Cedar is the correct choice when aesthetics are the primary driver and you're genuinely committed to the maintenance schedule. It's also excellent for covered or partially covered decks where direct rain exposure is limited — a cedar deck under a pergola or roof overhang ages far better than one exposed to full Seattle rainfall. If you have a strong vision for a natural wood aesthetic and you're prepared for the maintenance relationship, cedar can be a deeply satisfying choice. Our [cedar decking page](/cedar-decking) covers the installation details and what the maintenance schedule looks like in practice.

Composite Decking: What You Need to Know

Composite decking was invented to solve exactly the problems cedar presents in wet climates. The original composite boards — introduced in the 1990s — mixed wood fiber and plastic binders. They looked and cut like wood, needed no staining, and homeowners loved them.

The problem: that original uncapped composite still had exposed wood fiber, which absorbed moisture. In wet climates like Seattle's, that moisture enabled mold growth on and beneath the surface, causing early-generation composite boards to look terrible within a few years. If you've seen dark, mottled composite decking on a 10-year-old deck and wondered why people buy it — you were looking at uncapped composite in a wet climate.

Capped vs. Uncapped — The Most Important Distinction

The industry's solution was the capped composite board, introduced widely in the early 2010s. Capped composite has a continuous polymer shell — usually a blend of polyethylene or PVC — encapsulating all four sides of the board. Moisture cannot reach the wood fiber core. The board cannot absorb water, cannot mold from moisture ingress, and maintains its appearance with minimal care.

Only buy capped composite for a Seattle deck. Uncapped composite still exists on the market and it costs less — but you will regret it within three years in our climate.

Top Brands for the Pacific Northwest

Three brands consistently perform well in wet climates. Trex Transcend is the industry's most recognized capped composite and has an excellent track record in PNW conditions. TimberTech Legacy is another strong performer with a particularly realistic wood-grain texture and solid fade resistance. Fiberon Symmetry uses a proprietary polymer cap and has performed well in high-humidity applications. All three carry 25-year fade and stain warranties on their premium lines. Our [composite decking page](/composite-decking) goes into detail on each brand and what installation looks like.

The Real Maintenance Requirement

For any quality capped composite: rinse with a garden hose to remove debris. Occasional deck cleaner to address surface dirt or pollen. That is genuinely the full maintenance list over a 25-year warranty period. No sealing, no staining, no sanding. Compare that directly to the cedar maintenance schedule described above.

How They Compare in the Real World

The clearest way to understand the difference is to look at what each material looks like after 10 years in Seattle conditions.

A cedar deck that has been consistently maintained — sealed on schedule every one to two years — still looks beautiful at the 10-year mark, with visible weathering character that many owners find attractive. A cedar deck that has been partially maintained or neglected shows significant gray toning, surface checking, and in poorly ventilated areas, early mold or mildew in the end grain.

A capped composite deck at 10 years looks almost identical to the day it was installed. The surface shows minor wear from foot traffic, but the boards are structurally sound, the color is consistent, and there is no evidence of moisture damage.

We also install [PVC decking](/pvc-decking) for clients who want the absolute highest-performance option — 100% synthetic, no wood fiber at all, zero moisture absorption, and a performance record in the most extreme wet climates that is unmatched by any other surface material.

Our Honest Recommendation

For the majority of Seattle homeowners — we estimate about 90% — capped composite is the better choice. The upfront cost premium over cedar is offset by zero maintenance cost over a 25-year period, and the long-term performance in our climate is simply more reliable.

Cedar is the right call for covered or semi-covered decks where rain exposure is limited, for clients with a strong aesthetic preference for natural wood who are genuinely prepared for the maintenance schedule, and for projects where budget constraints make the lower upfront cost of cedar the deciding factor — with a clear-eyed understanding of future maintenance costs.

Not sure which direction is right for your project? We offer free material consultations where you can see actual samples of both materials and talk through the maintenance implications for your specific site. Call (425) 675-6259 or [request a free quote](/contact).