How to Plan a Deck Project

Quick answer

Quick steps

1. Pull the permit. Submit a site plan and framing drawing before any work begins. Most jurisdictions inspect footings, framing, and final finish in three separate site visits.
2. Dig and pour footings. Set concrete piers below the local frost line. Attach post bases after concrete cures, typically 28 days for full strength.
3. Frame beams, joists, and ledger. Follow your local joist span table. Flash the ledger connection to the house with metal drip cap or membrane to prevent rot.
4. Install decking boards. Leave a 1/8-inch gap between boards for drainage. Cut boards to length after installation, not before, for cleaner edges.
5. Install railing and stairs. Code sets minimum heights and baluster spacing. Stairs require consistent rise and run throughout the stair run.
6. Apply finish. Sand any rough edges, then apply sealer or stain to cedar or pressure-treated decks. Composite decking skips this step entirely.

What you'll need

• Permit application and site plan. A to-scale drawing showing deck dimensions, footing locations, ledger attachment point, and distance from property lines.
• Concrete and post bases. Tube forms, concrete mix or ready-mix, and galvanized post-base hardware rated for the post size.
• Framing lumber. Pressure-treated (PT) for all structural members: posts, beams, joists, and ledger. Cedar or PT is acceptable for decking boards depending on budget.
• Fasteners and hardware. Structural screws (not deck screws) for framing connections, joist hanger nails, ledger lag bolts, and corrosion-resistant deck screws or hidden fastener clips for decking boards.
• Railing components. Posts, top and bottom rails, balusters or cable hardware, and post base connectors.
• Sealer or stain. Required for cedar and pressure-treated decking. Composite decking does not need finish.

Pull permits

A permit is not optional for most decks. It protects you on resale and ensures the structure meets minimum load requirements.

• Attached decks almost always require a permit. Ledger connections transfer deck loads to the house structure. Building departments review this connection carefully.
• Elevation triggers permit requirements. Most jurisdictions require permits for any deck surface more than 30 inches above grade. Below that threshold, a freestanding ground-level deck may be exempt, but rules vary significantly by location.
• Permit costs run $100-500. Most residential deck permits fall in this range depending on deck size and your municipality. The inspection process adds 2-6 weeks to the project timeline.
• Submit a site plan with footing layout. Your plan needs to show deck dimensions, footing locations, setback distances from property lines and the house, and a basic framing elevation.

Plan footings and framing

Footings and framing are where structural errors happen. Undersized footings settle; undersized joists bounce. Use your local span tables, not rules of thumb.

• Frost line depth is non-negotiable. Footings must extend below the local frost line to prevent heaving. Frost depth ranges from 12 inches in southern states to 60 inches in northern climates. Your building department will confirm the required depth.
• Footing diameter scales with post load. A common starting point is a 12-inch-diameter concrete pier for posts supporting a residential deck, but your soil conditions and load area may require larger footings.
• Joist span table for pressure-treated lumber. The table below is a guide. Your permit drawings should reference your jurisdiction's adopted code (typically IRC or a local amendment).

Values are for Southern Pine No. 2, 40 psf live load, 10 psf dead load. Verify with your local building department. Use 16-inch spacing for all standard decking boards.

Estimate footing gravel and concrete quantities with the Gravel Calculator and Concrete Calculator.

Choose decking material

Material choice drives cost, maintenance schedule, and longevity more than any other single decision. The table below compares the four most common options.

Calculate exact board counts, fastener quantities, and material cost for your deck dimensions with the Deck Material Calculator.

Calculate fasteners and hardware

Fastener quantities are straightforward once you know board count, joist spacing, and whether you are face-screwing or using hidden clips.

• Face screws: 2 per joist crossing. A standard 5/4x6 board on 16-inch spacing uses 13 screws for an 8-foot run (7 joist crossings at 2 screws each minus end allowance). Practically: order 2.5 screws per linear foot of decking.
• Hidden fasteners: 1 clip per joist crossing per side. Most composite decking systems require one clip per groove side, so 2 clips per joist crossing total. Order 10% extra for damaged clips and railing post areas.
• Joist hangers: 2 per joist. Multiply your joist count by 2 (one hanger at each beam connection). Add beam-to-post hardware and post caps at each post location.
• Ledger lag bolts: every 16 inches staggered. Per IRC, a ledger must be fastened with 1/2-inch lag screws or through-bolts at 16-inch intervals in two staggered rows to transfer load safely to the house rim joist.
• Order 10% overage on all fasteners. Screws split boards, clips get dropped in dirt, and hanger nails are easily miscounted. Returning a partial box costs more in time than the extra box costs upfront.

Plan railing and stairs

Railing and stair code is frequently misunderstood. The IRC sets floors, but local amendments often go further.

• Railing height: 36 inches under 30 inches off grade; 42 inches above 30 inches. Measure from the deck surface to the top of the top rail. Most builders use 42 inches throughout for simplicity and forward compliance.
• Baluster spacing: 4-inch sphere rule. No opening between balusters, bottom rail, and deck surface should allow a 4-inch sphere to pass through. In practice, use a maximum of 4 inches of clear space between balusters.
• Stair rise/run: 7 3/4-inch max rise, 10-inch min run. IRC limits stair rise to 7 3/4 inches and run to a 10-inch minimum tread depth. All risers in a flight must be within 3/8 inch of each other. Variation causes trips.
• Stair handrail: required for 4 or more risers. A graspable handrail is required on at least one side when a stair has 4 or more risers. The graspable section must be between 34 and 38 inches above the stair nosing.
• Post attachment matters more than post size. A 4x4 post attached with a surface-mount post base is far weaker than the same post bolted through the rim joist or header. Structural post bases anchored through the framing are the correct detail.

Schedule the finish

• New pressure-treated lumber: wait 6 months before finishing. PT lumber contains moisture that prevents penetrating stains and sealers from bonding. Let it dry through one full season before applying any coating.
• Cedar: apply penetrating oil stain or water repellent within the first year. Cedar weathers to grey if left unfinished. A penetrating stain preserves the natural color and feeds the wood fibers. Reapply every 2-3 years or when water no longer beads.
• Composite decking: clean only. Capped composite boards do not absorb stain or sealer. Use a composite-safe deck cleaner once or twice a year. Power washing on a low setting removes mildew from textured surfaces.
• IPE: oil annually to keep color, or let weather naturally. Brazilian hardwood can be left to grey naturally without structural consequence. If you prefer the warm brown color, apply teak oil or IPE oil in the first month, then annually.

Estimate paint or sealer gallons needed for your deck surface area with the Paint Coverage Calculator.

Common mistakes

• Skipping the permit and inspection sequence. Uninspected decks are a significant liability at resale and may have to be torn down or rebuilt. Inspections also catch structural errors before they are buried under decking.
• Under-sizing footings for the soil type. Soft or expansive soils require larger footings. Building on undisturbed native soil is also critical: fill soil settles differently. Have your building department or a soils engineer review if the soil is questionable.
• Using standard deck screws for structural connections. Joist hangers, ledger bolts, and beam-to-post hardware require structural screws or bolts rated for those loads. Standard 3-inch deck screws are not structural fasteners.
• Not flashing the ledger. Where the ledger meets the house, water penetration rot is the most common cause of serious deck failure. Use a full-width metal or membrane flashing system, not just caulk.
• Installing railing posts surface-mounted to the rim joist. Surface-mounted posts rely only on fasteners through the rim joist face for lateral resistance. Through-bolt or use a through-frame post base for safe rail post attachment.

FAQ

Bottom line

Pull the permit first, set footings below frost line, frame to your local span table, choose a decking material that matches your maintenance tolerance, and finish in the right sequence. The most expensive deck mistakes are structural ones that get buried under decking before anyone looks closely. For exact material quantities, use the Deck Material Calculator.