Our 8×10 backyard transformation
How to build a floating deck. Start with your space.
A floating deck is a freestanding platform with its own support system. Start with the footprint, drainage and local requirements; then choose framing, supports and decking that work together. This planner estimates materials for a rectangular wood deck, while our project photos document our 8×10 platform over a concrete patio.
3D deck builder
Your deck, before the first cut.
Change the dimensions, direction and finish. Inspect the frame and save your materials list.
Purchase estimate
A material list that follows the model.
Installed pieces and purchase allowances stay separate so you can see what the waste factor changes.
- Surface area
- 80 sq ft
- Deck boards to buy
- 25 boards
- Joist stock to buy
- 7 boards
- Planning supports
- 21 locations
Plan basis10% purchase allowance0.125 in. planning gap15.75 in. modeled joist centers (16 in. maximum)Boards run across the width · 8-ft board run
Retail examples, not a complete order. Confirm species, grade, treatment, and hardware for your design. Wood tones do not select a product. Links are ordinary retailer links; no Home Depot sponsorship, live stock, or prices are represented.
| Material | Quantity & length | What the estimate includes |
|---|---|---|
| 5/4 × 6 pressure-treated deck boards | 25 boards at 8 ft | 22 installed full-width blanks plus 3 reserve blanks; buy 25 × 8-ft (25 pieces). Actual 1 × 5.5 in.; two edge rows rip to about 3.69 in. |
| Ground-contact 2 × 6 joist stock | 7 boards at 10 ft | 7 pieces at 9.75 ft; buy 7 × 10-ft (7 pieces). |
| Ground-contact 2 × 6 rim-board stock | 2 boards at 8 ft | Two pieces at 8 ft; buy 2 × 8-ft (2 pieces). |
| Ground-contact 2 × 6 blocking stock | 1 board at 8 ft | 6 pieces in the support interval nearest center, each 14.25 in.; buy 1 × 8-ft (6 pieces). |
| TuffBlock foundation supports | 21 blocks | 3 per joist row; 300 mm square footprint; centers 12 in. from the finished deck edges (10.5 in. from the cut joist ends) and 48 in. between centers in this preliminary layout. |
| Corrosion-resistant #8 decking screws | 339 screws | 154 board/joist intersections × 2, plus reserve: a purchase allowance, not a drilling pattern. Confirm the decking span rating, screw length, edge/end distances and treatment compatibility. |
| Corrosion-resistant #10 × 3 in. rim-decking screws | 38 screws | Allowance for two decking-to-top-of-rim lines at up to 6 in. on center, plus reserve. Confirm the final fastening detail and edge/end distances, especially at ripped edge boards; these do not connect the frame members. |
| Optional joist and rim flashing tape | 101 linear ft | Covers the top of joists, rims, and blocking; 91.4 linear ft net plus the selected reserve. Convert to rolls using the chosen product length. |
The real project
Same little yard.
A whole new place to stay.
Our Philadelphia patio already had concrete. What it lacked was a place that felt like an outdoor room. An 8-by-10-foot platform gave the seating and grill their own corner, with greenery and string lights doing the rest.
These are photographs of our build. The interactive deck above is a new planning model: its block layout and materials list are not a reconstruction of the hidden supports in these photos.
Walk through the complete backyard transformation →Before the first board
The ground makes
the first decision.
A deck calculator can count boards. It cannot see a soft patch of soil, a cracked slab, or the water that collects by your back door.
Measure the finished space
Mark the proposed perimeter on the ground and walk around it. Open the door fully. Pull a chair away from the table. Leave access to drains, meters and anything you may need to service. Record the height from the supporting surface to the intended deck surface as well as its width and depth.
Choose the support system for the site
Soil and an existing slab need different treatment. Rooftop decks are outside this guide. Our planner uses one direct-joist block arrangement to make the takeoff understandable. A sleeper system, adjustable pedestals or beams and posts need a separately checked layout. A patio slab is not automatically an adequate footing.
Read the TuffBlock installation instructions and confirm ground preparation, bearing, movement and restraint requirements for your site.
Follow the water
Check the area after rain. Preserve the route water takes away from the house, and leave the ventilation and clearance the decking system requires. Correct persistent ponding or a failing slab before covering it. Keep an inspection and cleaning route under the finished platform.
The Home Depot’s planning guide includes drainage, slope and soil among the site checks.
Check local requirements early
“Floating” is not a permit exemption. Ask about setbacks, height, guards, stairs, frost protection and whether the platform serves an exit. Philadelphia’s outdoor-deck guidance identifies decks higher than 12 inches as requiring a building permit—a good reason to avoid borrowing an exemption from another city.
From layout to last board
Build the parts you won’t see
with as much care as the surface.
Use this sequence to organize the work after the design and local requirements are settled. The photos show our patio preparation and frame assembly; they do not document every connection underneath the deck.
Step 1
Lay out the supports and frame
Before digging, driving ground stakes or installing ground anchors, arrange utility locating through 811 in the U.S. Follow the local waiting, response and safe-digging rules; private lines may need separate locating.
Transfer the approved layout to the site, check the diagonals for a square rectangle, and set the supports to the installation instructions. Check that each support bears as intended before adding weight.
On an existing slab, choose a system compatible with the slab and the available height. If the design requires anchors, their type, embedment, edge distances and slab suitability come from that design and the anchor manufacturer. There is no single concrete-screw size that makes every patio deck secure.
Step 2
Check the frame before it disappears
Install the specified joists, rims, blocking, connectors and restraint. Joist spacing follows the decking and structural design. The tool estimates a layout within a 16-inch maximum; a 12-inch layout needs a separately verified support arrangement. The estimate does not approve the decking or joist spans.
Check the grade stamp for species and grade, and the end tag for treatment and intended exposure. Ground-contact treatment can also be needed above ground where exposure or difficulty replacing structural members makes it appropriate. Recheck square, level, support contact and drainage before covering the frame.
Handle treated wood with care: use gloves when handling lumber, eye and dust protection when cutting or sanding, and hearing protection as the tool requires. Follow tool safety instructions. Collect sawdust and scraps, wash exposed skin and launder work clothes separately. Never burn treated scraps or use them as mulch; follow local disposal rules.
Step 3
Protect cuts and connections
Treat field cuts, ripped edges and drilled holes with the preservative specified by the lumber instructions and the field-treatment product label. Follow its application and handling directions; ordinary stain or joist tape does not replace required preservative treatment. If using joist tape, choose a compatible product, apply it to clean framing as directed, and account for overlaps. Tape is an optional protection layer; it cannot correct poor drainage or an unsuitable connection.
Select connector finishes and fasteners together. Simpson Strong-Tie’s guide explains the separate roles of framing connections and deck-board fasteners.
Step 4
Plan the final board before the first
Dry-lay the pattern so the last course does not become an awkward sliver. Use the decking manufacturer’s gap guidance for the actual product and its moisture condition. YellaWood’s building tips, for example, call for wet boards to be fitted tightly because they shrink as they dry. The gap in the calculator is an estimating input, not an instruction to install every wet or dry board the same way.
The model uses straight, single-piece wood boards. A picture-frame border, diagonal layout, composite deck or butt joints need a revised takeoff and supporting details.
Step 5
Fasten, finish and keep it accessible
Use the specified deck screws and installation pattern, including required end distances and predrilling. The calculator’s two-screw crossing count is a face-fastened decking allowance. Confirm that the actual decking is approved to span the chosen joist spacing, and check fastening room at ripped edge boards. Structural hardware is excluded until the connections are specified. Follow the finish manufacturer’s moisture and preparation requirements before staining.
Keep drains and the underside accessible, and include fasteners, connections and supports in routine checks. YellaWood’s treated-lumber guidance is one reference; follow the care instructions for the lumber you actually buy.
Turn the plan into a store list
Buy by the detail,
not just the total.
Use the materials list above to begin a lumber-yard or Home Depot conversation. Confirm the design and actual products before placing an order.
Return to your materials list ↑Lumber: Match actual board width, stock length, species, grade and treatment. Inspect for usable straight boards; a waste allowance does not guarantee every purchased piece can be used.
Supports: The illustrated TuffBlock count belongs to that arrangement. Another brand or a beam system may change both the spacing and quantity. Check physical clearance as well as bearing and site requirements.
Fasteners: Shop decking screws separately from any hanger, framing and anchor fasteners specified by the final design. Confirm compatibility with the treatment and connector metal.
The rest of the job: Allow for site preparation, any approved footings or bracing, cut-end treatment, finishing, tools, delivery and tax. These are outside the simple material quantities.
Retailer links help locate materials. They do not indicate a Home Depot sponsorship, confirm local stock, or make a listed product suitable for your site. No live prices are included.
The next chapter
First, a room for us.
Then, a room for the cats.
This backyard platform was an early step toward our later catio project. The enclosure, tunnel and roof bring their own design questions—and quite a different set of occupants.
See the 8×10 catio build →
Read the details
Sources behind the planning.
Reviewed September 11, 2026. The original project photos show what we built; manufacturer and building-authority documents guide the current planning notes. Check the current instructions for your exact product and location.
- BuildTuff: TuffBlock installation and product information
The specific direct-joist support system used for the planner’s preliminary layout. Check its current installation guide and the actual site before buying.
- BuildTuff: 2026 TuffBlock installation guide
The illustrated direct-joist example informs the planner’s support intervals and perimeter offsets. Lumber, connections, ground conditions and local requirements still need separate checks.
- YellaWood: building tips for treated lumber
Wet boards can shrink after installation. Installation spacing depends on the actual decking and moisture condition. Follow the lumber and preservative instructions for field treatment.
- American Wood Council: DCA 6 deck construction guide
Reference for wood-deck terminology and fastening. Its prescriptive system relies on attachment to a primary structure for lateral resistance; this freestanding planner is not a DCA 6 design.
- YellaWood: pressure-treated lumber questions
Treatment labels, ground-contact exposure, compatible fasteners and finishing.
- YellaWood: handling and disposal safety
Protection when cutting and handling treated wood, cleanup and disposal. Do not burn treated scraps or use them as mulch.
- Western Wood Preservers Institute: field treatment
Preservative treatment for cuts and drilled holes, following the lumber instructions and the field-treatment product label.
- 811: before you dig in the U.S.
Arrange utility locating before excavation. The person doing the digging must follow the local notification, response and safe-digging requirements; privately owned lines may need separate locating.
- Simpson Strong-Tie: deck connection and fastening guide
Connection details and corrosion considerations. Decking screws and structural connector fasteners serve different jobs.
- The Home Depot: planning and building a deck
Project planning, site conditions and the construction sequence. Its example details are not automatically the right design for this platform.
- Philadelphia L&I: outdoor deck requirements
The “Outdoor deck” section illustrates why local requirements matter: Philadelphia identifies decks higher than 12 inches as requiring a building permit. Ask your own authority about your project.
Project questions
Before you get the saw out.
What is the difference between a floating deck and a deck over concrete?
Floating describes a freestanding structure that does not rely on a house ledger for support. Over concrete describes its location. A platform above a patio may use a designed sleeper or pedestal system; the planner here illustrates a direct-joist block layout. Those systems have different support, drainage and connection requirements.
Do I need a permit for a low floating deck?
Ask your local building and zoning offices before buying materials. A small footprint or low height is not a universal exemption. Philadelphia, where our photographed project is located, identifies outdoor decks higher than 12 inches as requiring a building permit. Other local requirements can also apply.
How many support blocks do I need?
The calculator counts the support locations in its illustrated direct-joist TuffBlock layout. Changing the dimensions or board direction changes that count. The tool withholds quantities for its unverified 12-inch support arrangement. A beam-and-post design, another block, a pedestal system, or unsuitable soil can require a different layout. The result does not establish bearing capacity, frost protection or code compliance.
Can I put deck boards directly on a concrete slab?
Plan a substructure that supports the decking and preserves drainage, ventilation and the clearance required by the decking manufacturer. A slab must be assessed for condition and suitability for the chosen supports. Covering cracks or ponding water with timber does not correct the underlying problem.
Does changing the wood color change the materials list?
No. The colors are visual finish ideas on the same wood-deck geometry. They are not species selections, stain matches or a switch to composite. Changing material can change board dimensions, spacing, support requirements and fasteners, so this wood takeoff would need to be revised.
Does the screw total include the structural connections?
No. It estimates face-fastened decking screws and rim-decking screws only. Rim-to-joist connections, blocking connections, hangers, anchors and bracing need the fasteners specified by the final design. Their hardware quantities are excluded, not zero. Ordinary deck screws are not a substitute for specified connector fasteners.
Can this calculator design a deck for a hot tub, roof or catio?
No. It estimates a simple rectangular wood platform. Hot tubs, roofs, enclosures, guard posts, stairs, house connections and concentrated loads need their own design. Our catio is linked as a separate project, not as an addition this planner has evaluated.