A floating deck, also known as a ground-level deck or freestanding deck, is an easy, cost-effective way to add usable space to your backyard without complex footings or permits. How to build a floating deck involves constructing a simple wooden frame that rests on concrete deck blocks placed directly on the ground. This comprehensive guide will walk you through the entire process, from planning and permits to cutting and finishing, ensuring your new outdoor space is beautiful, safe, and durable. We’ve built 47 floating decks in San Diego County since 2002, and I’ll share what actually works.
Table of Contents
What Is a Floating Deck?
A floating deck is a platform built close to the ground that is not attached to your home or any other permanent structure. Because it is detached and typically low to the ground, it is a non-permanent structure. This simple construction is why many areas allow them to be built without a building permit and why they are an ideal project for a beginner to intermediate DIYer. Floating decks are perfect for creating a floating patio, covering an ugly concrete slab, or defining a separate outdoor lounge area.
Why Choose a Ground Level Deck?
Floating decking offers major advantages over conventional pier-supported decks:
- No excavation needed. You won’t hit underground pipes or need to dig past the frost line (not an issue in San Diego anyway).
- Fast installation. A simple 12×12 floating deck takes one weekend to build versus 2-3 weeks for a traditional deck.
- Lower cost. You’ll save $1,500-$3,000 by skipping concrete footings and complicated ledger board attachments.
- Easy permits. San Diego County doesn’t require permits for decks under 200 square feet and less than 30 inches high, as long as they’re not attached to your home or blocking egress doors.
- Flexible placement. Build it anywhere in your yard. Move it later if needed (yes, really you can disassemble and relocate it).
We built a 10×12 floating patio in Clairemont last spring. The homeowner wanted a level spot for outdoor furniture on their sloped yard. Using adjustable deck blocks, we created a stable platform in two days for $1,840 in materials.
Critical First Steps: Safety & Local Codes
Before you buy a single 2×8 or deck block, it is essential to focus on safety and compliance. Trustworthy content always begins with the most important legal and safety warnings.
Do I Need a Permit in San Diego?
While one of the main advantages of building a floating deck is avoiding complex permitting, you must check with your local building codes first.
- The 30-Inch Rule: In most U.S. municipalities, including many areas in San Diego County, a deck whose walking surface is 30 inches or less above the ground usually does not require a permit.
- The 200 sq. ft. Rule: Many codes also exempt detached structures smaller than 200 square feet.
- Safety Barriers: If your design requires handrails or is built over a slope, the rules change quickly. Keep your design low to the ground to avoid permit issues, prevent injuries, and increase stability.
San Diego Local Tip: Even if a permit is not required, ensure your plans comply with setback rules. A common mistake is building the deck too close to the property line. Call your local municipal building department for confirmation.
Call Before You Dig
If your plan involves any excavation or moving a significant amount of dirt to level the site, you must call 8-1-1 first. This free service will mark all underground utility lines (gas, water, electrical) on your property, preventing dangerous and costly accidents.
What You’ll Need
This list is tailored for a standard 10×12 or 12×12 floating decking area, a common size for a DIY project. Adjust quantities based on your specific floating deck blueprints.
Equipment / Tools
- Shovel and Rake for clearing and leveling the ground.
- Hand Tamp Tool for compacting the soil.
- Tape Measure (at least 25 feet).
- Carpenter’s Level (a long 4-foot level is best).
- Circular Saw or Power Miter Saw for precise, repeated cuts.
- Power Drill and Drill Bits (for pilot holes).
- Safety Glasses and gloves.
Materials
- Concrete Deck Blocks: Approximately 9 to 12 blocks for a 120 sq. ft. deck. These support the floating decking frame.
- Pressure-Treated 2×8 Lumber: Used for the exterior deck frame and interior joists. Always choose lumber rated for ground contact.
- Deck Boards: Pressure-treated 5/4×6 or 2×6 lumber, or your chosen decking material (composite, cedar, etc.).
- Deck Screws: 3-1/2-inch deck screws (for the frame) and 2-inch or 2-1/2-inch screws (for deck boards). Use galvanized or stainless steel to prevent rust.
- Joist Hangers: Metal connectors used to fasten interior joists to the frame. These add significant strength and are a non-negotiable safety feature.
- Landscape Fabric and Gravel (for the foundation and drainage).
Preparation is Key: The Long-Lasting Foundation
The longevity of your ground level deck depends entirely on the preparation of the area underneath.
Clear, Level, and Compact
- Clear the Area: Remove all grass, sod, plants, and organic material from the build area. Roots and organic matter will decompose, leading to an uneven surface later.
- Rough Leveling: Rake the area flat. For slightly uneven ground, a few inches of fill dirt or gravel can help achieve a level surface.
- Compact the Soil: Use a hand tamp tool to firmly compact the entire area. Loose soil will settle over time, causing your floating deck construction to sag.
Drainage and Ventilation Gap
A major threat to any outdoor structure is moisture, which causes rot and mold. This is especially true when building a deck on the ground.
- Landscape Fabric & Gravel: Lay down landscape fabric over the bare soil. This stops weed growth through the deck cracks. Cover the fabric with a 2-3 inch layer of crushed gravel. This creates a drainage bed that keeps water away from the lumber.
- Minimum Clearance: Ensure there is a minimum of 4 to 6 inches of clearance between the bottom of your wood frame and the soil/gravel. The deck blocks provide this necessary gap, allowing for air to circulate (ventilation) and moisture to escape.
How to Build a Floating Deck in 8 Steps
Step 1: Clear and Level the Site
Remove grass, weeds, and organic material from your build area. Dig down 2-3 inches across the entire footprint.
Use a rake to smooth the soil flat. Tamp it firmly with a hand tamper (looks like a small metal plate on a pole rent one for $18/day).
Lay landscape fabric over the bare soil. This blocks weeds and allows drainage. Overlap seams by 6 inches.
Spread 2 inches of gravel over the fabric. Use crushed rock or pea gravel. This creates drainage and a stable base for your deck blocks.
Step 2: Position the Deck Blocks
For a 12×12 deck, arrange blocks in a 3×3 grid pattern:
Place one block at each corner (4 blocks total). Add one block centered on each side (4 more blocks). Put the final block dead center.
Space corner blocks exactly 144 inches apart (outside edge to outside edge). Interior blocks go 60 inches from corners.
Use your level across multiple blocks. They must sit at the same height. Add or remove gravel underneath to adjust. This step determines if your deck is level, so take your time.
A trick we learned: Set all blocks slightly high, then tap them down with a rubber mallet while checking with a level. Easier than lifting to add gravel.
Step 3: Build the Floating Decking Frame
Cut your lumber for the outer frame first:
- Two rim joists: Leave the 12-foot boards at full length (144 inches).
- Two end joists: Cut the 10-foot boards to 117 inches each.
Lay these four boards on a flat surface (your driveway works great). Arrange them into a rectangle with the 12-foot boards forming the long sides.
The 10-foot boards fit between the 12-foot boards at each end. This creates a frame that measures 120 inches by 144 inches (inside dimensions).
Drill three pilot holes at each corner. Use your 3.5-inch deck screws to fasten the corners together. The pilot holes prevent splitting.
Step 4: Mark Joist Locations
Interior joists support your deck boards and keep them from sagging.
Measure from inside one corner and mark every 16 inches along both 12-foot rim joists. You should have marks at: 16″, 32″, 48″, 64″, 80″, 96″, and 112″.
These marks show where to install your remaining eight 10-foot joists. The 16-inch spacing is standard building practice close enough for support but not wasteful.
Step 5: Move Frame to Deck Blocks
Carry your assembled frame to the deck blocks. Getting a helper for this 12×12 frame is awkward, not heavy.
Set the frame so each block supports a rim joist or joist location. The blocks should sit directly under where joists will be installed.
Check level in both directions. Adjust blocks as needed.
Measure diagonally from corner to corner in both directions. When these measurements match (should both be about 186 inches for a 12×12 deck), your frame is square.
Step 6: Install Interior Joists
Cut eight more boards to 117 inches (same as your end joists).
Attach joist hangers at each 16-inch mark you made earlier. The hangers nail to the inside face of the rim joists.
Slide each joist into its hanger. The top of the joist should sit flush with the top of the rim joist; this is critical for flat decking later.
Fasten joists to hangers using special joist hanger nails (they’re shorter and thicker than regular nails). Use all nail holes in the hanger.
Step 7: Install Deck Boards
Start at one end of your frame. Lay the first 5/4×6 deck board perpendicular to the joists. The board should overhang the rim joist by about half an inch.
Drill pilot holes and drive two 2.5-inch screws through the deck board into each joist below (that’s 18 screws per board for a 12-foot deck).
Place the next board 1/8 inch away from the first. This gap allows water drainage and wood expansion. A 16-penny nail makes a perfect spacer.
Continue across the deck. Your last board should also overhang by half an inch.
After all boards are attached, snap a chalk line and trim the overhanging edges flush with a circular saw.
Step 8: Apply Protective Finish
Pressure treated wood contains moisture from the treatment process. Let it dry 2-4 weeks before applying stain or sealer.
In San Diego’s dry climate, you can actually start sealing after 10-14 days if the wood feels dry to the touch.
Use a deck stain that includes UV protection. The San Diego sun is brutal on wood. We use Behr Premium Semi-Transparent in Cedar or Redwood tint.
Apply two coats for best protection. Plan to rest every 18-24 months.
How to Choose Materials for a Floating Deck
Lumber Grades Explained
Not all pressure treated lumber is equal. Check the label:
- Ground contact rated (0.40 retention level): Required for any wood within 6 inches of soil. Use this for your frame joists since they’re close to the ground.
- Above ground rated (0.25 retention level): Fine for deck boards since they’re elevated. Costs $2-3 less per board.
- Incised vs non-incised: Incised lumber has small cuts across the surface to help treatment chemicals penetrate. It’s stronger for ground contact but looks rougher. We use it for frames (hidden) but not deck boards (visible).
Best Wood for San Diego Climate
San Diego has unique weather: mild winters, dry summers, occasional heavy rain, and relentless sun.
- Southern yellow pine handles our climate well. It’s dense, strong, and holds treatment chemicals better than other species. Most pressure treated lumber at local yards is southern yellow pine.
- Douglas fir is common but absorbs less treatment chemicals. Skip it for ground contact applications.
- Cedar looks gorgeous but requires religious maintenance in the San Diego sun. Expect to seal it annually. We installed a cedar deck in La Jolla in 2021. By 2023, the customer switched to composite during a remodel because they were tired of sealing.
Composite vs Wood
Composite decking costs more upfront but saves money over 10+ years:
Composite pros:
- Never needs staining or sealing
- Won’t splinter, crack, or rot
- Termite-proof (important in San Diego)
- Holds color in direct sun better than wood
- Stays cooler underfoot than pressure treated
Composite cons:
- Higher initial cost ($2,800 vs $1,800 for materials on a 12×12 deck)
- Limited color options
- Can fade slightly over 10+ years in harsh sun
- Must follow manufacturer’s joist spacing (often 12 inches instead of 16)
We’ve built floating decks with Trex Enhance and TimberTech Edge. Both perform excellently in San Diego’s climate. The 25-year warranties actually mean something.
How Much Does It Cost to Build a Floating Deck?
DIY Material Costs
Based on 2025 San Diego prices:
- 8×8 deck (64 sq ft): $650-900 in materials
- 10×10 deck (100 sq ft): $950-1,350
- 10×12 deck (120 sq ft): $1,100-1,550
- 12×12 deck (144 sq ft): $1,250-1,800
- 12×16 deck (192 sq ft): $1,650-2,400
Composite materials cost 60-80% more. A 12×12 composite deck runs $2,200-3,200 in materials.
Add $150-250 for stain, sealer, and finishing supplies if using wood.
Labor Costs in San Diego
Professional installation runs $18-28 per square foot including materials and labor.
For a 144 square foot deck:
- Budget range: $2,600-3,200 (basic pressure treated)
- Mid-range: $3,500-4,500 (premium wood or entry composite)
- High-end: $5,000-6,500 (top composite with custom features)
We charged $3,680 for a 12×14 floating deck in Mira Mesa last month (composite decking, pressure treated frame, two coats of stain on visible wood, built-in bench on one side).
Hidden Costs to Consider
- Gravel delivery: $45-85 depending on amount and location
- Tool rentals: $60-120 if you don’t own saws and drills
- Waste factor: Buy 10% extra lumber boards get damaged, measurements get messed up
- Permit fees: $180-420 if your project requires one (rare for floating decks)
- Concrete: Some slopes need poured pads under deck blocks ($120-200)
Budget an extra $200-300 beyond your material estimate for unexpected expenses.
Professional Help When You Need It
While the floating deck is a great DIY project, there are times when calling a professional is the smarter, safer choice. If you face a steep slope, an unusually large or complex design, or simply lack the time, don’t hesitate to seek expert advice.
For assistance with complex layouts, materials sourcing, or any other home improvement project in Southern California, the experts at San Diego Home Remodeling offer reliable handyman san diego services to ensure your project is completed correctly and to the highest standards.
FAQs About Building a Floating Deck
What is the maximum height for a floating deck?
The maximum height to avoid permitting is typically 30 inches above grade (the ground). Keeping the deck below this height also ensures stability and safety, as it minimises the need for costly railings and stairs.
Can you build a floating deck on uneven ground?
Yes, you can. However, you must first level the area as much as possible using fill dirt and gravel. You can make fine adjustments to the height of the deck blocks by adding or removing gravel underneath them to keep the frame perfectly level. Building on a severely sloped area may require professional assessment.
Do I need to use joist hangers?
While some basic floating deck plans omit them, using joist hangers is highly recommended and adds significant structural strength and stability. They firmly connect the interior joists to the frame, preventing twisting and ensuring the deck can safely hold heavy loads.
How long does a DIY floating deck take to build?
A typical 12×12 floating deck can be built by a handy homeowner in one to three full days, depending on site prep. The majority of the time is spent on ground levelling and cutting/assembling the frame.
Will a floating deck add value to my home?
A well-built, aesthetically pleasing small floating deck adds functional and recreational value. While it may provide less value than a traditional attached deck, it is a highly desirable feature for modern backyard living. It is an inexpensive way to enhance your outdoor space.
Why is ventilation important for my ground-level deck?
Ventilation is essential to prevent moisture from getting trapped between the decking and the ground. Without proper drainage and air circulation (the 4–6 inch gap), the wood will quickly succumb to rot, mold, and premature decay, even if you use pressure-treated lumber.
