A floating deck — also called a freestanding or self-supporting deck — stands entirely on its own posts and footings without connecting to your house. An attached deck uses a ledger board bolted to your home's rim joist to share the structural load. For most Seattle homeowners, the choice isn't just structural preference — it's about whether your home's back wall can handle a ledger connection correctly in a climate with 150+ wet days per year.
The Structural Difference: Ledger vs. Self-Supporting
An **attached deck** shares load with your home through a ledger board — a horizontal timber bolted directly to the rim joist behind your siding. One edge of the deck frame rests on this ledger, which reduces the number of posts and footings needed on that side. The tradeoff: you're creating a wood-to-house connection that must be flashed and sealed precisely to keep water out of the building envelope.
A **freestanding deck** (also called a floating or self-supporting deck) stands entirely on its own post-and-footing system positioned close to the house but not attached to it. It needs additional posts along the house side where an attached deck would use a ledger — but it makes no penetrations into the building envelope and eliminates the ledger connection entirely.
Both approaches produce a structurally sound deck when built correctly. The question for Seattle homeowners is which one is correct for your home's specific construction.
Why the Ledger Connection Is a Bigger Deal in Seattle
The ledger connection is the single most failure-prone element in residential deck construction — industry data attributes roughly 60% of structural deck failures to improper ledger installation or ledger rot. In Seattle's climate, that risk is significantly elevated.
Seattle gets more than 150 wet days per year. Wind-driven rain at this latitude angles into structures differently than straight vertical rainfall, pushing water behind flashing details that would hold fine in a drier climate. When water infiltrates behind a ledger board, it migrates into the OSB sheathing and rim joists — damage that stays invisible until boards become soft and fasteners lose their hold. By the time a homeowner notices, the repair scope has grown from a deck project to structural remediation running $3,000–$8,000 before a single deck board is purchased.
Most Seattle homes built before 1990 were constructed with ledger flashing details that don't meet current code. Some have no flashing at all. Homes with fiber cement siding (HardiePlank), stucco, or any existing water damage near the back wall present specific challenges that make an attached deck significantly more expensive — or structurally inadvisable. The PNW case for freestanding is strong in a way it simply isn't in Phoenix or Atlanta.
5 Signs a Freestanding Deck Is the Right Call
**1. Your home was built before 1990.** Older homes frequently have undersized rim joists, non-code ledger connections from a prior deck, or OSB sheathing that has already seen moisture exposure. A freestanding structure avoids uncovering remediation work mid-project.
**2. You have fiber cement or stucco siding.** Both require specialized flashing sequences to penetrate correctly. Fiber cement needs a precise siding cutback, Z-flashing, and sealant detail. Stucco requires a different approach entirely. Errors in either system are expensive and slow to reveal themselves. A freestanding deck removes the question entirely.
**3. Your existing deck showed water damage at the house end.** If the deck being replaced had soft spots near the ledger, or if a site inspection finds darkened sheathing or soft rim joist material, building freestanding prevents reattaching to compromised framing.
**4. You're on a hillside lot with significant grade change.** On steep lots in Bellevue, Mercer Island, Issaquah, or North Seattle where the deck surface is 8–12 feet above grade at the far edge, a self-supporting post system is often structurally preferred regardless of ledger concerns — it distributes lateral loads differently and avoids transferring those forces into the house wall.
**5. Your home has no roof overhang above the rear wall.** An overhang above the ledger provides meaningful protection from wind-driven rain. Flat rear walls with no overhang subject the ledger connection to maximum weather exposure year-round, increasing the long-term maintenance burden on that flashing detail.
When an Attached Deck Is the Better Choice
An attached deck is appropriate — and generally less expensive — when:
- Home was built post-2000 with vinyl or newer wood siding in good condition - Rim joist at the attachment point is accessible, sound, and correctly sized - A roof overhang provides weather protection above the rear wall - No evidence of prior moisture intrusion at the back wall - Contractor site inspection confirms clean, unobstructed framing
The cost savings come from 4–6 fewer posts and footings on the house side — typically $1,500–$3,500 in materials and labor on a 300–400 sq ft deck. That advantage disappears if the attachment point requires siding remediation, custom flashing work, or rim joist repair.
Cost Comparison: Freestanding vs. Attached in Seattle
| Cost Factor | Attached Deck | Freestanding Deck | |---|---|---| | Ledger installation | $800–$2,000 | None | | Siding remediation risk | $0–$3,500 | None | | Rim joist repair risk | $0–$2,500 | None | | Additional posts and footings | Baseline | +$1,500–$3,500 | | Below-frost footing requirement | Required on all posts | **WA code exemption applies** | | Permit drawing complexity | Ledger detail required | Simpler structural package | | **Net difference — clean home** | Baseline | **$1,000–$2,000 more** | | **Net difference — ledger issues** | **$2,000–$5,000 more** | Baseline |
One factor that surprises homeowners: Washington State Residential Code includes a specific provision that **freestanding decks not supported by a dwelling do not require footings that extend below the frost line**. In Seattle's clay-heavy soils, frost-depth footings typically reach 18–24 inches. Eliminating that requirement on the house-side posts partially offsets the additional post count on a freestanding build.
Both structure types use the same surface materials. Composite decks run $35–$55 per sq ft installed, PVC runs $45–$65 per sq ft, and cedar runs $20–$35 per sq ft in King County regardless of whether the structure is attached or freestanding. Our [deck cost guide](/deck-cost-seattle) has current numbers by material and project size.
Permit Requirements in Seattle and King County
Both attached and freestanding decks require a building permit in Seattle if the walking surface is more than 18 inches above grade — a threshold most backyard decks exceed. A freestanding deck under 200 sq ft with a walking surface below 18 inches may qualify for a permit exemption, but this applies to very small, low-to-ground platforms, not full outdoor living decks.
The practical permit difference: attached decks require a ledger connection detail in the structural drawings, adding a review element that freestanding decks don't have. On straightforward freestanding builds, this occasionally simplifies the plan check package and shortens review time.
In unincorporated King County, the permit threshold shifts to 30 inches above grade rather than 18 inches. Cities including Bellevue, Sammamish, and Kirkland follow their own adopted codes but generally mirror Seattle's 18-inch rule. For a full city-by-city breakdown of permit timelines and requirements, see our [deck permit guide for King County](/blog/deck-permit-king-county-guide). We handle permit applications in every King County jurisdiction.
HOA Considerations
HOAs in planned communities — Issaquah Highlands, Sammamish Plateau, Klahanie, and many Bellevue neighborhoods — typically don't distinguish between attached and freestanding construction in their architectural guidelines. Their review focuses on deck height, setbacks from property lines, materials, and colors. The structural approach is generally the contractor's decision, not the HOA's.
HOA architectural approval must come before a permit application regardless of deck type. Our [HOA deck approval guide](/blog/hoa-deck-approval-king-county) covers the full King County submission process.
The Bottom Line for Seattle Homeowners
For homes built after 2000 with vinyl or newer wood siding and a clean back-wall inspection: attached is usually the right call. Fewer posts, lower cost, and structurally sound with proper ledger flashing.
For homes built before 1990, homes with fiber cement or stucco siding, homes where we find evidence of prior water intrusion at the back wall, or hillside lots where structural engineering is required regardless: we recommend freestanding. In a climate with 150+ wet days per year and 37+ inches of annual rainfall, eliminating the ledger penetration risk is worth the additional post cost.
The right answer depends on what a contractor finds at your specific wall. That's exactly what our free site assessments are designed to answer — we inspect the back wall, tell you which structural approach fits your home, and give you a written quote with no surprises.
**Call us at [(425) 675-6259](tel:4256756259) or [request a free estimate](/contact) — we build freestanding and attached decks across all of King County and know the housing stock in every neighborhood we serve.**