A well-built deck adds living space, increases home value, and provides years of outdoor enjoyment. Most handy homeowners can build a ground-level or low-elevated deck themselves — the skills required are basic carpentry, familiarity with a circular saw and drill, and the ability to work safely at height if any part of the deck is elevated.
This guide covers the full planning and building process, from design and permits through post footings, framing, decking installation, and finishing. For materials, use our deck calculator to get an accurate count of boards, joists, posts, and hardware before purchasing.
Phase 1: Design and Permits
Before buying a single piece of lumber, spend time on design and permits. This is where projects succeed or fail in the planning stage.
Design decisions
- Size and shape: A 12×16 foot deck (192 sq ft) is a comfortable starting size for most homes. Simple rectangles are easiest to build and most cost-effective.
- Height: Ground-level decks (under 30 inches high) typically have simpler permit requirements. Elevated decks require guardrails and stringent footing engineering.
- Attachment: Ledger-attached decks attach to the house framing — simpler to build but require careful flashing to prevent water infiltration. Freestanding decks don’t attach to the house — more footings required, but no ledger flashing concerns.
- Decking direction: Standard is perpendicular to the house. Diagonal or picture-frame patterns require more material but look distinctive.
Permits
In most jurisdictions, any deck attached to the house or over 200 sq ft requires a permit. Check with your local building department. Permit costs range from $150–600. Required inspections typically include footings (before concrete), framing, and final.
Never skip permits for a deck. Unpermitted decks create liability issues, may prevent home sale, and require demolition when discovered.
Phase 2: Material Selection
Pressure-Treated Lumber (PT)
The standard choice for framing (posts, beams, joists, ledger). Modern PT lumber uses CA-C (copper azole) treatment, which is safer than older CCA. Always use hot-dipped galvanized or stainless hardware with PT lumber — regular steel corrodes.
For decking boards: PT lumber warps significantly as it dries. If using PT for deck surface boards, buy them early and let them acclimate for a few weeks, or buy kiln-dried PT.
Composite Decking
Premium composite boards (Trex, TimberTech, Azek) cost 2–3x more than PT lumber upfront but require virtually no maintenance. No sanding, no staining, no warping. Excellent for busy families. Calculate your composite needs with our deck calculator.
Cedar and Redwood
Naturally rot-resistant, easier to work with than PT, takes stain beautifully. More expensive than PT, less available than composite. Requires annual sealing or staining to maintain.
Hardware
Never cut corners on hardware. Use joist hangers, post bases, beam connectors, and ledger bolts rated for pressure-treated lumber. The hardware cost is a small fraction of total project cost but critical to structural integrity.
Phase 3: Footings
Footings are the foundation of your deck — if they fail, the deck fails. Most residential decks use concrete tube footings (Sonotubes).
Footing depth
Must extend below the frost line in your area. Check your local building code. In northern climates, this means 36–48 inches. In mild climates, 12–18 inches may be acceptable.
Undersized or too-shallow footings are the most common serious defect in DIY decks. A heaving footing from freeze-thaw cycles will tilt the deck, crack the ledger connection, and potentially separate the deck from the house.
Sizing footings
A structural engineer or your building department can specify footing size. For a typical residential deck on non-expansive soil, 12-inch diameter footings under 6×6 posts are common. Larger decks or soft soil conditions require larger footings.
Mixing concrete
Use a concrete mixer or pre-mixed bags. For footings, Quikrete Fast-Setting Concrete is popular — you pour it dry into the hole and add water, no mixing required. Our concrete calculator can tell you how many bags you need for your footing count and dimensions.
Phase 4: Posts and Beams
Posts
Set post bases in wet concrete (or use the Fast-Setting method), plumb them precisely, and brace temporarily until the beam is installed. 6×6 posts are standard for most residential decks; 4×4 is acceptable for very low, small decks.
Beams
Double or triple 2× material fastened together (with structural screws and/or bolts) forms the beam that supports the joists. Engineered lumber (LVL beams) is stronger, dimensionally stable, and available in longer lengths — worth considering for spans over 10 feet.
Beam span tables determine the appropriate beam size for your post spacing and joist span. Your building department or a structural engineer can provide these.
Phase 5: Ledger and Rim Board
The ledger is the pressure-treated board bolted to the house framing that carries the inner end of your joists. It’s the most critical connection on an attached deck.
Flashing — non-negotiable
Every ledger must be flashed. Water infiltrating behind a ledger is the leading cause of deck collapse. The ledger sits against the house — if water gets trapped there, it rots the house band joist in 5–10 years, silently, until the connection fails catastrophically.
Use full-coverage ledger flashing tape, or Z-flashing, and follow the manufacturer’s installation guide precisely. This is not a step to improvise.
Ledger fasteners
Use structural lag screws or through-bolts, not nails or deck screws. Fastener pattern and spacing are specified in code — typically 16-inch spacing in a staggered pattern.
Phase 6: Joist Framing
Joists run from the ledger to the beam, typically 12 or 16 inches on center. Use joist hangers at the ledger end and rest on or attach to the beam at the outer end.
Blocking between joists (mid-span and at joist ends) prevents lateral movement and is required by most codes.
Crown your joists: every piece of lumber has a slight bow. Install with the crown (curved side) up so the joist deflection under load works with, not against, the lumber’s natural shape.
Phase 7: Decking Boards
Spacing
Leave 1/8 inch gap between boards for drainage and expansion. Use a 16d nail or specialized spacers. Gaps that are too tight trap debris; gaps that are too wide look bad and are uncomfortable underfoot.
Fastening
Use hidden fasteners (Camo, Ipe Clip, Trex Hideaway) for a clean, fastener-free surface. Face screwing is faster and cheaper but creates water-trapping holes and a more utilitarian look. For composite decking, follow the manufacturer’s fastener specifications.
Snapping lines
Rather than measuring each board individually, snap chalk lines to keep rows parallel and verify straightness as you go.
End cuts
Run all boards long, then snap a chalk line and cut the overhang flush with the rim joist using a circular saw. This is much faster than cutting each board to exact length before installation.
Phase 8: Railings, Stairs, and Finishing
Railings are required for decks more than 30 inches above grade. Code typically requires 36-inch height (42 inches for commercial), 4-inch max baluster spacing, and a graspable handrail.
Stairs require consistent riser height (max 7.75 inches in most codes) and tread depth (min 10 inches). Stringer design is critical — notch depth should not reduce stringer depth below 5 inches.
Finishing PT lumber requires the lumber to fully dry before applying stain (typically 6–12 months). Apply water repellent sealer annually on natural wood. Composite decking only needs cleaning.
Estimating Your Materials
Before buying anything, calculate your complete material list:
- Count footings based on your post layout
- Calculate post length based on deck height + frost depth + 6-inch concrete embedment
- Size beams using span tables
- Count joists based on deck length ÷ spacing + 1
- Calculate decking boards using our deck calculator
- List all hardware: post bases, joist hangers, beam hardware, screws, and fasteners
Our deck calculator handles the decking board count and joist count automatically. For footings and concrete, use our concrete calculator.
Typical Costs (2026)
| Component | DIY Cost | Contractor Add |
|---|---|---|
| Footings + concrete | $400–1,200 | +$800–2,000 labor |
| Framing lumber | $800–2,500 | +$1,500–3,500 labor |
| PT decking boards | $600–1,800 | +$1,000–2,500 labor |
| Composite decking | $2,000–5,000 | +$2,000–4,000 labor |
| Railings | $400–1,500 | +$800–2,000 labor |
| Hardware and fasteners | $300–700 | — |
A 12×16 foot PT deck fully built by a contractor typically runs $8,000–16,000. DIY on the same deck can run $3,000–6,000, saving $5,000–10,000 in labor.
FAQ
Do I need a permit to build a deck? In most jurisdictions, yes — especially for attached decks or any deck over 200 sq ft. Always check your local building department before starting. Unpermitted decks create serious problems when selling your home.
What wood is best for deck posts? Use ground-contact rated pressure-treated lumber (marked UC4B or UC4C) for posts that contact soil or concrete. Standard PT (UC3B) is acceptable for posts that don’t contact the ground.
How long will a PT wood deck last? With proper maintenance (sealing every 1–2 years), a PT deck can last 20–30 years. The decking boards may need replacement before the framing wears out. Composite decking lasts 25–30 years with minimal maintenance.
Can I build a deck without footings? Ground-level “floating” decks on concrete pads or precast pier blocks are possible for very low, small structures. But in frost climates, any structure without below-frost footings will heave seasonally. Always check local code for minimum requirements.
How far apart should deck joists be? 16 inches on center is standard and works with most decking materials. 12 inches provides more stiffness and is better for diagonal decking or thinner composite boards. 24 inches requires heavier decking and is less common.
Plan your deck materials accurately with our deck calculator — enter deck dimensions and get board counts, joist count, and hardware list for your project.