How long does it typically take to build a new deck?

A straightforward deck project usually takes one to three weeks from the start of framing to the final walkthrough, depending on size and complexity. Permitting adds time before construction begins, since footing and framing inspections have to be scheduled with the local jurisdiction. Weather can also push timelines, since footings and framing go faster during drier stretches.

What questions should I ask before hiring a deck builder?

Ask whether they pull permits and handle inspections themselves, what fastener and hardware grade they use, and how they detail the ledger flashing where the deck meets the house. Ask to see how they handle footing depth for your specific soil rather than a generic minimum. A contractor who can answer these clearly and specifically, without vague reassurance, is usually one who builds this way as a habit, not an exception.

Is composite decking worth the extra cost over wood?

It depends on how much time you want to spend maintaining it. Capped composite costs more upfront than pressure-treated lumber but skips the annual sealing and staining that wood needs to resist moisture and moss, which can make it the better value over a 20-plus year timeframe, especially in shaded yards. Wood remains a solid, lower-cost option for homeowners willing to keep up with regular maintenance.

What's the difference between pressure-treated lumber and cedar for decking?

Pressure-treated lumber is chemically treated to resist rot and insects and is generally the lower-cost option, but it needs consistent sealing to perform well long-term. Cedar has natural oils that resist decay and insects without chemical treatment and has a warmer, more natural appearance, but it's typically a higher material cost and still needs periodic oiling to prevent graying and moss buildup.

Do I need a permit to build a deck in Seattle or unincorporated King County?

In most cases, yes — decks above a certain height or size require a permit, with inspections at the footing and framing stages before decking goes down. The exact requirements and which department handles them depend on whether the property sits inside Seattle city limits or in unincorporated King County, so it's worth confirming before finalizing plans. We handle this coordination as part of the build.

Expert Deck Building for Seattle Homes

Building Decks for Seattle's Climate, Not a Catalog Photo

A deck built for a dry climate doesn't automatically work here. Seattle sees a long, wet stretch of the year where a deck spends most of its life damp, shaded, and slowly growing moss — and homes close to Puget Sound also deal with salt-laden air that speeds up corrosion on anything metal. A deck that looks right on install day but wasn't built with these conditions in mind will show problems within a few seasons: soft boards near the house, rust bleeding from fasteners, and a green film that never fully goes away no matter how often you scrub it.

We build decks in Seattle and around King County with those conditions as the starting assumption, not an afterthought. That means flashing details, fastener choices, and drainage planning that match what this specific climate does to outdoor structures, not generic best practices pulled from a builder's manual written for a different part of the country.

What Seattle Weather Actually Does to a Deck Over Time

It helps to understand the failure pattern before talking about how to prevent it. In this region, decks don't usually fail from one dramatic event — they fail slowly, from repeated exposure that a homeowner doesn't see until the damage is already underneath the surface.

Driving Rain and Trapped Moisture

Rain that comes in sideways during a windstorm gets pushed against the house wall and under the ledger board — the piece that attaches the deck to the structure. If that connection isn't flashed correctly, water works its way behind the siding and into the rim joist, which is exactly where you don't want rot starting, because it's structural and hidden from view.

Moss and Algae Growth

Long stretches of shade, moisture, and mild temperatures are ideal growing conditions for moss and algae. On a deck, that shows up first in low-traffic corners and under railings, then spreads across board surfaces. Beyond looking bad, a mossy deck surface gets slick and holds moisture against the wood fibers longer, accelerating decay underneath the growth.

Salt Air and Fastener Corrosion

Homes nearer to the water deal with airborne salt that attacks unprotected steel. Screws, nails, and joist hardware that aren't rated for coastal or high-moisture exposure will rust, weep stains down the decking, and eventually lose holding strength years before the wood itself would have failed.

Choosing the Right Decking Material for This Climate

There's no single "best" decking material — there's a best material for your budget, your maintenance tolerance, and how much shade and moisture your specific site gets. Here's how the common options compare for a Seattle-area deck.

Material	Moisture & Moss Resistance	Maintenance	Typical Lifespan
Pressure-treated lumber	Good with proper sealing; still needs airflow to shed moisture	Annual cleaning, resealing every 1-2 years	15-25 years
Cedar	Naturally moisture- and insect-resistant, but surface still needs care	Cleaning and oiling every 1-2 years to prevent graying and moss	15-20 years
Capped composite	Excellent — sealed cap resists moisture absorption and moss staining	Periodic washing, no sealing or staining	25-30+ years
Uncapped composite	Moderate — can absorb moisture at cut edges over time	Regular cleaning; more prone to surface mold in shaded areas	15-25 years

For decks in heavily shaded yards or under tall evergreens — common throughout King County — we generally steer homeowners toward capped composite or well-maintained cedar, since both hold up better against the moss and algae growth that plagues low-sun areas. Pressure-treated lumber is still a solid, budget-friendly choice, but it depends more heavily on the homeowner keeping up with sealing.

The Structural Details That Actually Matter Here

The decking boards get all the attention, but the parts you don't see are what determine whether a deck lasts fifteen years or thirty. In a climate this wet, we treat the following as non-negotiable, not upgrades:

Ledger Flashing

The ledger-to-house connection is the single most common point of failure on decks in this region. Proper flashing — installed in the correct order relative to the house's weather-resistive barrier — keeps water from migrating into the wall assembly. This is also one of the first things a building inspector checks, and for good reason.

Joist Protection

Covering the tops of joists and beams with a self-adhering flashing tape stops water from pooling in screw holes and along cut edges, which is where rot typically starts on an otherwise sound frame.

Footings Set for Local Soil

King County's soil conditions vary by neighborhood, and footings need to be sized and set to the appropriate depth for the site and local frost line, not just poured to a generic minimum. Undersized or shallow footings are a common source of deck movement and settling over time.

Corrosion-Resistant Fasteners and Hardware

We use fasteners and structural hardware rated for exterior and coastal exposure throughout, not just at the ledger. It costs more up front than standard hardware and is far cheaper than dealing with rust stains and failed connections down the road.

Permits, Code, and Railings in King County

Most new decks above a certain height or size require a permit, and inspections happen at specific stages — typically footings and framing before the decking goes down. Requirements differ slightly depending on whether the property is inside Seattle city limits or unincorporated King County, so it's worth confirming which jurisdiction applies to your address before work starts.

A few code points that come up on nearly every project:

Guardrails are generally required once a deck surface is a certain height above grade, with minimum height requirements for the railing itself
Baluster spacing is limited so a small child can't pass through the railing
Stair rise and run, along with handrail requirements, are checked for consistency and grip-ability
Ledger attachment and flashing details are commonly reviewed as part of framing inspection

We handle the permit submission and coordinate inspections as part of the build — it's not an extra homeowners need to manage on their own.

How We Approach a Deck Build, Start to Finish

Every property is different, but the process generally follows the same stages:

Site assessment — checking sun exposure, drainage patterns, existing structure condition, and soil at the footing locations
Design and material selection — sizing the deck to the space and matching materials to how shaded, exposed, or high-traffic the area will be
Permitting — submitting drawings and structural details to the relevant jurisdiction and scheduling required inspections
Demolition and footings — removing any old structure and setting footings to proper depth for the site
Framing — ledger flashing, joist layout, and hardware installation, built to pass inspection the first time
Decking, railings, and stairs — installed with attention to fastener spacing and drainage gaps between boards
Final walkthrough — going over the finished deck and what maintenance it will need going forward

Keeping Moss and Algae From Taking Over

Even a well-built deck needs some upkeep in a climate that grows moss on the roof, the fence, and the deck alike. A short seasonal routine keeps it from becoming a bigger job later:

Sweep debris and fallen needles off the deck regularly — trapped organic matter holds moisture and feeds moss growth
Wash the surface at least once a year with a deck-safe cleaner, focusing on shaded corners and under railings
Keep nearby shrubs and tree branches trimmed back to let sunlight and air reach the deck surface
Check and clear drainage gaps between boards so water isn't pooling instead of shedding through
Reseal wood decking on the schedule appropriate to the product — don't wait until it's visibly gray or cracking
Look over railings and stair connections once a year for any looseness or rust weeping from fasteners

Why Hiring a Crew That Already Works in Seattle Matters

A lot of deck problems we get called to repair weren't built badly out of carelessness — they were built to specifications that make sense somewhere drier. Flashing details get skipped because they "usually" aren't needed, fastener grades get downgraded to save cost, and footing depth gets treated as a formality instead of something the local soil and frost conditions actually require.

Working in and around Seattle and King County day to day means we already know which details can't be shortcuts here, which jurisdictions require what for permitting, and which materials genuinely hold up through a Pacific Northwest wet season instead of just looking good when they're new. That local familiarity shows up less in the sales pitch and more in the parts of the deck you never see once it's finished — the flashing, the hardware, the footings — which is exactly where it matters most.

Get a Straightforward Estimate for Your Deck

If you're planning a new deck, or replacing one that's showing its age, we're happy to come take a look, walk the site with you, and put together a clear, no-pressure estimate built around your yard's actual sun, shade, and drainage conditions. Reach out through the form below to get started.