A floating deck sits directly on the ground using precast deck blocks instead of buried concrete footings. It is not attached to the house, which in most jurisdictions means no permit, no frost-line depth requirements, and no ledger board lag-bolted into your rim joist. For homeowners who want a ground-level outdoor living space without the complexity and cost of a traditional elevated deck, learning how to build a floating deck is the most practical weekend project available.
Part of our Decks & Outdoor guide — explore the full guide →
What Makes a Deck “Floating”
A floating deck, also called a freestanding or grade-level deck, rests on the ground surface rather than being anchored to the home’s foundation. Precast concrete deck blocks (like the Deckorators 11-inch block or similar products at $7-$10 each) sit on compacted gravel and support the joists directly. Because the structure is not attached to the house, it moves independently with freeze-thaw cycles rather than fighting them.
Most floating decks sit 1 to 6 inches above ground level. This low profile means no railing is required by code in most areas (railings are typically mandated when the deck surface is 30 inches or more above grade). The result is a clean, open platform that blends into the landscape.
Materials List for a 10×12-Foot Floating Deck
A 10×12-foot deck is one of the most popular sizes for a DIY floating build. It provides 120 square feet of usable space, enough for a table and four chairs or a pair of lounge chairs with side tables. Here is what you need.
- Deck blocks: 9 precast blocks arranged in a 3×3 grid ($63-$90)
- Joists: 6 pressure-treated 2×8 boards at 12 feet long, spaced 16 inches on center ($90-$120)
- Rim joists/header: 2 pressure-treated 2×8 boards at 10 feet long ($30-$40)
- Decking: 20 composite boards at 12 feet or equivalent square footage in 5/4×6 pressure-treated lumber ($240-$700 depending on material)
- Joist hangers: 6 Simpson Strong-Tie LUS28 hangers ($24)
- Deck screws: 5-pound box of 2-1/2-inch exterior-rated screws or hidden fastener clips ($25-$60)
- Gravel: 3/4-inch crushed stone for block pads, about 0.5 cubic yards ($25-$35)
- Landscape fabric: One 4×50-foot roll to suppress weeds under the deck ($15-$20)
Total material cost ranges from $500 to $800 for pressure-treated lumber decking or $900 to $1,400 with composite boards.
Site Preparation
Choose a flat or gently sloping area at least 2 feet from the house foundation to allow airflow. Mark the deck footprint with stakes and string. Remove sod within the footprint and 6 inches beyond each side. Spread landscape fabric over the exposed soil to block weed growth, then cover it with 2-3 inches of compacted 3/4-inch crushed stone.
Leveling the site is the most time-consuming part of the project. Use a long straight 2×4 and a 4-foot level to check grade across the area. For gentle slopes (less than 12 inches of drop across the deck length), you can compensate by stacking deck blocks or using adjustable post bases. Slopes greater than 12 inches need a terraced or elevated deck design rather than a floating platform.
Step-by-Step Construction
- Place deck blocks: Set 9 blocks in a 3×3 grid with outer blocks at the corners and midpoints of each side, and one center block. Space the rows 5 feet apart (center to center) along the 12-foot dimension. The channels in the blocks accept 2×8 joists laid flat or on edge depending on the block design.
- Set the outer beams: Place two 12-foot 2×8 boards into the outer rows of deck blocks. These serve as your primary beams. Level them using shims or by adding or removing gravel beneath the blocks. Confirm they are parallel and exactly 10 feet apart (outside to outside) by measuring diagonally. Equal diagonal measurements mean square corners.
- Install rim joists: Attach the two 10-foot 2×8 rim joists across the ends of the beams using structural screws or 3-inch lag screws. This creates the rectangular frame.
- Hang interior joists: Mark the inside of each beam at 16-inch intervals. Install joist hangers and set the interior 2×8 joists. Each joist should bear on the center row of deck blocks for mid-span support, preventing bounce.
- Square and level the frame: Recheck diagonals, shim any low blocks, and confirm the frame is level across all directions. This is your last chance to make corrections before decking covers the frame.
- Install decking: Start from the house side (or the most visible edge) and work outward. Overhang the decking 1 to 1-1/2 inches past the rim joist on the sides. Leave a 1/8-inch gap between boards for drainage. Pre-drill the ends of boards to prevent splitting. For composite decking, use the manufacturer’s hidden fastener system.
- Trim and finish: Snap a chalk line along the overhanging board ends and cut a straight line with a circular saw. Attach fascia boards to the rim joists if desired to cover the frame and create a finished edge.
Common Mistakes to Avoid
Skipping the gravel base is the biggest mistake DIYers make when learning how to build a floating deck. Deck blocks placed directly on soil settle unevenly as the ground absorbs water and freezes. Even 2 inches of compacted gravel distributes the load and provides drainage that keeps the blocks stable season after season.
Using undersized joists is another frequent error. A 2×6 joist spanning 10 feet at 16-inch spacing deflects noticeably under foot traffic. Upgrade to 2×8 for spans over 8 feet to eliminate the bouncy, unsteady feel that undermines the entire project. The cost difference between 2×6 and 2×8 lumber is $2 to $4 per board, a trivial price for structural integrity.
Permit Requirements and Code Considerations
Most municipalities exempt freestanding decks under 200 square feet and under 30 inches above grade from permit requirements. However, this is not universal. Some HOAs and local jurisdictions have setback requirements, impervious surface limits, or specific rules about ground-level structures. Call your local building department before starting. A five-minute phone call prevents a code enforcement notice after the deck is built.
Even without a permit, build to code standards for your own safety. Use pressure-treated lumber rated for ground contact (look for the UC4A or UC4B stamp) for any framing member that contacts the deck blocks. Use stainless steel or hot-dip galvanized fasteners that will not corrode from contact with treated lumber’s copper-based preservatives.
Estimated Timeline and Cost Summary
Two people can build a 10×12-foot floating deck in a single weekend: Saturday for site prep and framing, Sunday for decking and finishing. Working solo adds another half day. The total project cost ranges from $500 to $1,400 depending on decking material choice, with most of the budget going to the decking boards themselves. Compared to a contractor-built attached deck at $25 to $50 per square foot installed, a DIY floating deck at $4 to $12 per square foot represents significant savings with comparable usability for ground-level applications.
