How to Build a Deck: Complete Planning Guide

Why Planning Matters More Than Building

Building a deck is one of the most rewarding DIY projects a homeowner can take on. It adds usable outdoor living space, increases your home's value, and provides years of enjoyment. But a deck that is poorly planned — wrong size, wrong location, wrong materials, or no permit — creates headaches that far outlast the building process.

This guide walks you through every planning decision you need to make before picking up a hammer. Get the planning right, and the building phase becomes a matter of following a clear sequence of steps.

Step 1: Define Your Purpose and Size

Start by asking how you will actually use the deck. The answer determines the size, shape, and features you need.

• Outdoor dining for four to six people requires a minimum of 12x12 feet (144 square feet) to accommodate a table, chairs, and room to move.
• Grilling and entertaining typically needs 12x16 feet (192 square feet) or larger, with space for a grill station, seating, and foot traffic.
• A large gathering space or multi-use area may call for 16x20 feet (320 square feet) or more, possibly with multiple levels or zones.

A common mistake is building too small. Once furniture, a grill, and people are on the deck, the space fills quickly. Mock up the footprint in your yard with stakes and string to visualize the actual size before committing.

Step 2: Choose a Location

The best location balances access, sun exposure, privacy, and views.

• Access from the house. A deck connected to the kitchen or living room through a sliding or French door gets the most use. If no door exists, factor in the cost of adding one.
• Sun and shade. Consider where the sun hits at different times of day. A west-facing deck gets intense afternoon sun in summer, which may require a pergola or shade structure. An east-facing deck is pleasant in the morning but shaded by afternoon.
• Setbacks. Your local zoning code specifies how close a structure can be to property lines (called setbacks). Common setbacks are 5 to 10 feet from side and rear property lines. Check your zoning ordinance before finalizing the location.
• Utilities. Call 811 (the national "call before you dig" number) before digging any footings. Underground gas lines, electrical conduits, water pipes, and cable lines must be located and avoided. This service is free and required by law in most states.

Step 3: Understand Permits and Codes

A building permit is not optional for most deck projects, and the inspection process is there to protect you.

What the Permit Requires

• A site plan showing the deck's location on your property relative to the house and property lines.
• Construction drawings showing the framing plan, footing layout, beam sizes, joist spacing, railing height, and stair details.
• Specification of materials and fasteners.

Key Code Requirements

While codes vary by jurisdiction, the following are common across most areas:

• Footings must extend below the frost line (the depth at which the ground freezes). This ranges from 12 inches in the southern United States to 48 inches or more in northern states.
• Ledger boards (the board that attaches the deck to the house) must be properly flashed and bolted to the house rim joist with lag screws or through-bolts. Nails are never acceptable for ledger attachment. Improper ledger connections are the leading cause of deck collapses.
• Railings are required on any deck surface more than 30 inches above grade. Railing height must be at least 36 inches (42 inches in some jurisdictions). Baluster spacing must not allow a 4-inch sphere to pass through.
• Stairs must have consistent riser heights (typically 7 to 7.75 inches) and tread depths (at least 10 inches). A graspable handrail is required on stairs with four or more risers.

Step 4: Choose Your Decking Material

The decking material is the largest material cost and the surface you will see and walk on every day. Each option has trade-offs.

Pressure-Treated Lumber

• Cost: $2 to $5 per linear foot for 5/4x6 decking boards.
• Pros: Lowest cost, widely available, easy to cut and fasten, strong. Modern pressure-treated lumber uses micronized copper azole (MCA) or alkaline copper quaternary (ACQ) treatments that are effective and safer than the older CCA formulations.
• Cons: Requires annual or biannual staining or sealing to prevent graying, splitting, and warping. Can splinter. Will check (develop surface cracks) over time. Must be allowed to dry before staining — typically 3 to 6 months after installation.
• Lifespan: 15 to 25 years with regular maintenance.

Composite Decking

• Cost: $5 to $12 per linear foot for standard composite boards. Premium brands cost more.
• Pros: Extremely low maintenance — no staining, sealing, or painting required. Resists rot, insects, and splintering. Available in a wide range of colors and wood-grain textures. Most brands offer 25-year or lifetime limited warranties.
• Cons: Higher upfront cost. Can get hot underfoot in direct sun (especially darker colors). Feels different from real wood. Cannot be refinished if deeply scratched. Requires composite-specific hidden fasteners.
• Lifespan: 25 to 50 years with minimal maintenance.

Tropical Hardwoods

• Cost: $8 to $15 per linear foot for species like ipe, cumaru, or tigerwood.
• Pros: Exceptional beauty and natural durability. Extremely hard and dense — ipe is rated for 40+ years even without finish. Naturally resistant to rot, insects, and fire.
• Cons: Very expensive. Extremely hard to cut and drill (carbide-tipped blades are required). Heavy. Requires pre-drilling for every fastener. Must be oiled periodically to maintain color, or it will weather to a silver-gray.
• Lifespan: 40 to 75 years.

PVC Decking

• Cost: $7 to $12 per linear foot.
• Pros: Completely waterproof — will not absorb moisture, stain, or support mold growth. Lighter than composite. Good for docks and pool decks.
• Cons: Can feel plasticky underfoot. Expands and contracts more than wood or composite with temperature changes. Limited color options compared to composite.
• Lifespan: 25 to 50 years.

For the framing structure underneath the decking boards — posts, beams, and joists — pressure-treated lumber is the standard choice regardless of what decking material you use on top. The substructure is hidden and does not require the aesthetic or low-maintenance properties of composite or hardwood.

Step 5: Plan the Substructure

The substructure is the skeleton of the deck: footings, posts, beams, and joists. Getting this right is essential for a safe, long-lasting deck.

Footings

Footings transfer the deck's weight to the ground. The two most common types are:

• Poured concrete footings. Dig a hole below the frost line, insert a cardboard tube form (such as a Sonotube), and pour concrete. A metal post bracket is set into the wet concrete to hold the post above the concrete surface.
• Precast concrete pier blocks. Suitable only for ground-level, freestanding decks that do not require deep footings. These sit on a compacted gravel base and are not appropriate for elevated or attached decks in most jurisdictions.

Footing size and spacing depend on the load they carry. A common configuration for a residential deck is 12-inch diameter footings spaced 6 to 8 feet apart along each beam line.

Posts, Beams, and Joists

• Posts are vertical members (typically 4x4 or 6x6 pressure-treated lumber) that sit on the footings and support the beams.
• Beams run horizontally across the tops of the posts and carry the weight of the joists and decking. A common beam for residential decks is a doubled 2x8 or 2x10, depending on the span.
• Joists run perpendicular to the beams and directly support the decking boards. Standard joist spacing is 16 inches on center for most decking materials, or 12 inches on center for some composite products. Use joist hangers (metal brackets) to attach joists to beams and ledger boards.

Step 6: Estimate Your Costs

Here is a materials cost estimate for a 12x16-foot (192 square foot) deck with a single staircase and railing on three sides:

Add 10 to 15 percent for waste, miscalculations, and unexpected needs. If you hire a contractor for the labor, expect to roughly double the total cost.

Essential Tools

You do not need a professional workshop, but you do need reliable tools:

Common Mistakes to Avoid

• Skipping the permit. An unpermitted deck can result in fines, required removal, increased liability, and problems at resale. The permit process also ensures your design is structurally sound.
• Inadequate footings. Footings that are too shallow will heave with freeze-thaw cycles, shifting the entire deck. Always dig below the frost line.
• Improper ledger attachment. The ledger board must be bolted (not nailed) to the house framing with proper flashing behind it to prevent water from entering the wall. Ledger failure is the number-one cause of deck collapse.
• Ignoring drainage. The area under the deck should slope away from the house foundation. If water pools under the deck, it can undermine footings and damage the foundation.
• Not leaving gaps between decking boards. Wood and composite both need room to expand. Leave a 1/8-inch gap between boards for drainage and expansion. Many hidden fastener systems create this gap automatically.

The Building Sequence at a Glance

Once your plan is finalized and your permit is in hand, the construction follows this general order:

1. Lay out the deck footprint with string lines and stakes.
2. Dig and pour footings. Allow concrete to cure for at least 48 hours.
3. Set posts and cut to height.
4. Install beams on top of the posts.
5. Attach the ledger board to the house (if the deck is attached).
6. Install joists on the beams and ledger using joist hangers.
7. Install blocking between joists as required by your plan.
8. Lay decking boards, starting from the house side and working outward.
9. Build and install stairs.
10. Install railings and balusters.
11. Schedule final inspection with your building department.

Each of these steps has specific techniques and details that deserve attention. Take your time, check for level and square frequently, and do not move to the next phase until the current one is solid. A well-built deck provides decades of outdoor living and is one of the most satisfying projects a homeowner can complete.