Ask House Spouse · Exterior & Weatherproofing · Decks & Outdoor Structures
What does it cost to repair or replace a deck in the Seattle area?
Short answer
The cost to redo a deck varies widely with the scope. A simple restain or replacing a few rotten boards on a 12x12 deck might cost $1,500 to $4,000. Re-decking (replacing all boards and railings) on a solid frame could be $5,000 to $10,000, while a complete rebuild with new structure can easily cost $15,000 to $30,000 or more.
Understanding the Scope: Repair, Re-Deck, or Rebuild?
The term 'redo' can mean three different things. A repair involves fixing specific problems, like replacing a few rotten boards or securing a wobbly railing. Re-decking (or re-skinning) involves removing all the old surface boards and railings and installing new ones onto the existing frame. This is only an option if the underlying structure is in excellent condition. A full rebuild means tearing everything down to the ground, pouring new footings, and constructing an entirely new deck, a major project requiring permits and significant investment.
Key Factors Driving Deck Costs in Washington
Several variables impact the final price. Material choice is the biggest: pressure-treated lumber is the most affordable, cedar offers natural rot resistance at a mid-range price, and composite decking (like Trex or TimberTech) has the highest upfront cost but the lowest long-term maintenance. The complexity of the design also matters. Stairs, intricate railings, built-in benches, or multiple levels all add considerable labor and material costs compared to a simple, flat square deck.
The Real Culprit: Water Intrusion and Rot
In the PNW, deck longevity is a battle against water. Improper construction is a common hidden problem. Decks built without proper flashing over the ledger board can funnel water directly into your home's framing, causing catastrophic damage. Posts set directly in concrete or soil will wick moisture and rot from the bottom up. Regular maintenance is your best defense. Keeping the deck clean of debris and applying a quality stain or sealer every 2-3 years prevents water from penetrating the wood in the first place.
Repair vs. Replace: Making the Call
If your deck's substructure (the posts, beams, and joists) is solid, repairs and re-decking are great options. Replacing surface boards, railings, or stairs can give you the look and feel of a new deck for a fraction of the cost of a full build. However, if our assessment finds widespread rot in the framing, if the ledger board is compromised, or if the footings are failing, a full replacement is the only safe option. Investing in repairs on a failing structure is both unsafe and a waste of money.
Why it happens
Decks in the Pacific Northwest fail primarily due to constant moisture exposure. The relentless rain, combined with freeze-thaw cycles, causes wood to expand and contract, leading to cracks. If not cleaned and sealed regularly, water penetrates the wood, causing rot. This decay is most aggressive at connection points: where posts meet concrete, where joists meet beams, and especially where the deck attaches to the house at the ledger board. Debris like leaves and needles traps moisture against the surface, accelerating the process.
How to diagnose it
- 1Check for softness with a screwdriver. Probe the wood on posts, joists, and stair stringers, especially near the ground or connections. If the tool sinks in easily, it's a sign of rot.
- 2Inspect the ledger board. Look where the deck attaches to your house. Check for proper metal flashing, any signs of discoloration on your siding, or gaps that let water behind the board.
- 3Shake the railings and posts. They should be firm with very little give. Significant wobbling indicates loose fasteners or, more likely, rot at the connection points.
- 4Examine the surface boards. Look for widespread cupping (curling edges), deep cracks, splintering, or dark, discolored patches that stay damp long after rain.
- 5Look underneath the deck. Scan the joists and beams for any sagging, cracking, or visible rot. Ensure posts are not in direct contact with soil or sitting in puddles.
DIY vs. professional
DIY-friendly if…
A homeowner can safely clean and apply a new coat of stain or sealer to a deck that is structurally sound.
Call a pro when…
Call a professional for any structural work, including replacing joists, posts, or ledger boards, as this is critical to safety and often requires permits. My House Spouse handles deck board and railing replacement on sound structures.
Cost expectations
$1,500–$30,000typical WA labor + materials
Cost varies dramatically. A simple board replacement and restain might be $1,500-$4,000. A full rebuild with new footings and composite materials can cost $15,000-$30,000+ for a standard deck.
Every House Spouse job is quoted in writing before we start. 12-month workmanship warranty included.
What we see on Home Health Assessments
Around 74% of PNW roofs we assess show active moss establishment — accelerates shingle wear by an estimated 3–5 years if untreated.
Caught early on assessment: $220–$650 · Left until failure: $3,500–$22,000
During a Home Health Assessment, we conduct a thorough deck safety inspection. We'll probe all critical structural members for rot, check the ledger board flashing, and evaluate the overall condition to give you a clear recommendation for repair versus replacement.
How the Home Health Assessment worksServices we'd bring to this job
Where we handle this
We answer this question on real Home Health Assessments across Snohomish and King County.