Floating / Ground-Level Deck
A floating or ground-level deck is the build path for any residential deck where the surface is less than 30 inches above grade at every point — the threshold below which Seattle DCI does not require a building permit, Washington State Residential Code does not require guardrails, and the deck can install on adjustable polymer pedestals (Bison Pedestal, Eterno IVICA, Wallbarn) or precast concrete piers (DekBlock-style) without poured concrete footings. The build skips the engineering review and the permit queue, which compresses the total project timeline from a 2-month elevated-deck pipeline to a 1 to 2-week installation. The trade-off is that the build only fits a flat or near-flat back yard where the surface can stay under the 30-inch threshold, and the absence of poured footings means the deck is genuinely floating — it can shift slightly with ground movement, which is acceptable structurally for a ground-level deck but is the reason these are not the right path for an elevated build. From $8,000 for a 12-by-12-foot 144 square-foot pressure-treated floating deck to $18,000 for a 16-by-20-foot 320 square-foot capped composite or cellular PVC floating deck with picture-frame border, integrated low-voltage lighting, and a built-in bench. Drainage detailing is the critical line item in PNW exposure — the gravel base, the slight slope toward natural drainage, and the air gap under the deck — because ponding water under a floating ground-level deck is the most common cause of premature joist rot and mildew. Any line-voltage lighting circuit routes to a licensed Washington L&I electrician.
Service
How the Floating Deck Build Works
Five sequential phases from site assessment and drainage analysis to final walk-through — the actual working sequence we run on every floating ground-level deck under 30 inches above grade, no permit and no engineering needed.
Site Assessment, 30-Inch Threshold Confirmation, Drainage Analysis
Estimate visit confirms the back yard stays under 30 inches above grade across the entire intended footprint (so no Seattle DCI permit is required and no railing is required by code), identifies the existing storm drainage flow direction, and checks whether the deck location ponds water in the wet season. Ponding zones are the most common reason a floating deck fails prematurely in PNW; we either route around them or fix the drainage before the deck goes in.
Excavation, Weed Barrier, Gravel Base Sloped to Drain
Deck footprint excavates 2 to 4 inches below grade. Permeable landscape weed barrier (Mirafi 140N or equivalent) lays across the excavation. 2 to 4 inches of 3/4-inch minus crushed gravel goes on top of the barrier, sloped at 1/4 inch per foot toward whichever direction the yard naturally drains. The base suppresses weed growth, gives the pedestals a stable bearing surface, and lets water that gets under the deck percolate through rather than pond against the joist underside.
Polymer Pedestals or Precast Concrete Piers Laid Out on the Grid
Adjustable polymer pedestals (Bison Versadjust, Eterno IVICA, Wallbarn) thread up or down to precise heights with built-in slope correctors, or precast concrete piers (DekBlock-style) stack on the gravel where the base is flat enough. Pedestal grid spacing typically 4 to 6 feet on center based on joist sizing. Each support point gets leveled across the field with a laser level so the joist top is flat regardless of grade variation in the gravel base.
PT 2x Frame Up — Free-Standing or Attached with Flashed Ledger
Joists in PT 2x8 at 16-inch OC for face-fastened lumber, 12-inch OC for hidden-fastener composite or PVC. Beams sized to span between pedestals where required. Most floating decks are built free-standing (no ledger to the house) because it is structurally simpler and avoids re-triggering a permit through the building-envelope code question on an attached deck. If attached, the ledger gets the same full continuous flashing detail we use on elevated builds.
Decking + Optional Single Step + Optional Lighting + Final Walk
Decking installs in the homeowner-selected material (PT or cedar for budget builds; capped composite or cellular PVC for low-maintenance). Picture-frame border boards mitered at corners. Single step down to surrounding lawn or patio (no handrail required under 30 inches above grade). Low-voltage post-cap or perimeter lighting if specified — Handis runs the low-voltage wire; licensed Washington L&I electrician handles any new line-voltage circuit. Final walk with you, no inspection required since no permit was pulled.
Floating / Ground-Level Deck Pricing
Final pricing depends on square footage, decking material selection (PT is the most affordable; cellular PVC is the premium), support system (adjustable polymer pedestals vs precast concrete piers), drainage remediation if the back yard needs it before the deck goes in, and integrated lighting scope. No Seattle DCI building permit is required and no structural engineering is required because the deck surface stays under 30 inches above grade — so those pass-through line items do not appear on the quote. The licensed Washington L&I electrician's portion (for any new line-voltage circuit) is named line by line if integrated lighting is in scope. Request a free in-home estimate for an accurate quote.
Send us back-yard photos with rough elevation context (we need to confirm the deck stays under 30 inches above grade across the footprint), the deck size, and the decking material — we will quote the floating build.
Why Handis for Floating Ground-Level Decks
The floating ground-level decks we are called to repair almost always failed for one of two reasons — water ponded under the deck because the drainage was wrong from day one, or the polymer pedestals settled into a gravel base that was not properly compacted before pedestal placement. Both failures trace to the prep work, not to the decking material or the framing. Handis spends the same time on the drainage analysis and the gravel base preparation on a floating deck that we spend on the footing layout for an elevated deck — because the gravel and the slope are the foundation on a floating build. We will not quote a floating deck over a ponding zone without also quoting the drainage remediation; if the drainage cannot be fixed, the right answer is sometimes a different deck location or a deck on actual concrete piers rather than pedestals.
Estimate
Tell us the back-yard layout (flat or gently sloped, where the deck location is relative to the house, whether the back yard ponds water in the wet season), the rough size you have in mind (12x12, 12x20, 16x20 are the most common), the decking material (PT, cedar, capped composite, cellular PVC), free-standing or attached, and any add-ons you want priced (integrated lighting, built-in bench, drainage remediation). We send back a clear estimate.
Customer Reviews
Floating ground-level deck construction reviews from real Seattle-area Handis customers.
1968 Wedgwood rambler, flat back yard, wanted a 14-by-18-foot floating deck off the back door for the BBQ and a dining table. Handis confirmed on the estimate visit that the entire footprint stayed under 30 inches above grade (so no permit and no railing was required), walked the yard during a wet afternoon, and identified one corner that ponded after rain. They re-graded the corner with a French drain to a side-yard swale (named on the quote at $1,800), then built the deck on adjustable polymer pedestals over a compacted gravel base. One-and-a-half working weeks. Three years in and the underside is bone dry every time I look.
We had a quote from another contractor that was $4,000 less but did not include any drainage analysis or any mention of the gravel base prep — just talked about laying joists directly on patio blocks. Handis was upfront on the estimate that the gravel base and the slope-to-drain were the line items that make a floating deck last, and named both on the quote. We paid the premium and got a 12-by-16-foot PT floating deck that has stood through five wet winters with zero joist rot at the underside. Glad we listened.
Cellular PVC floating deck on a 16-by-20 footprint for a Magnolia rambler back yard. Handis installed the AZEK boards over Bison Versadjust pedestals on a compacted gravel base. The leveling was perfect across the entire 320 square feet despite the back yard having a slight grade — the pedestal slope correctors handled it. The integrated low-voltage perimeter lighting (named on the quote with the licensed electrician's circuit add at $480) makes the deck usable into evening every summer. Two working weeks total, no permit needed.
1958 Wallingford bungalow, modest back yard, wanted a small 12-by-12 PT deck off the kitchen door for a few chairs and a grill. Handis kept it simple — precast concrete piers on a compacted gravel base, PT 2x8 joists at 16-inch OC, 5/4 PT decking, single step down to the lawn, picture-frame border. Came in at $8,200. One working week. The boards weathered to grey within 12 months and look like they have always been there.
We wanted the deck attached to the house instead of free-standing for aesthetic continuity with the house siding. Handis added the flashed ledger as a named line item ($950 add-on), did the full continuous metal flashing assembly that they use on elevated decks, and photographed it before the deck boards closed it in. 14-by-16-foot capped composite with hidden fasteners and a built-in bench at one end. One-and-a-half working weeks. The bench doubles as the back edge of the deck and gives us extra seating for evening gatherings.
Frequently Asked Questions
Common questions about floating and ground-level deck construction — pricing, permits, drainage, polymer pedestals vs piers, and what to expect on a Handis build.