How to Build a Backyard Wood Deck
Construct a sturdy ground-level or raised wood deck from footings and structural framing to securing joists, laying decking boards, and trimming edges cleanly.
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🧰 Required Tools & Equipment
- ✓ Post hole digger or auger
- ✓ 4-foot spirit level
- ✓ Circular saw
- ✓ Cordless impact driver
- ✓ Speed square
- ✓ Chalk line
- ✓ Tape measure
📦 Materials & Supplies
- ✓ Pressure-treated 4x4 posts
- ✓ Pressure-treated 2x8 framing lumber
- ✓ 5/4x6 decking boards
- ✓ Quick-setting concrete mix
- ✓ Metal joist hangers and structural screws
- ✓ 3-inch exterior deck screws
⚠️ Safety Checkpoints & Warnings
- • Call 811 before digging to locate all buried utility lines.
- • Wear safety glasses and a dust mask when cutting pressure-treated lumber.
- • Use proper lifting techniques or a second person when setting heavy beams and wet posts.
📋 Step-by-Step Guide (6 Steps)
Lay Out and Dig Footings
Set up batter boards and masonry string lines to mark the deck perimeter. Use the 3-4-5 triangulation method across the string corners to guarantee square corners. Dig post holes below your local frost line at your marked layout locations.
- • Taut string lines forming a rectangle with identical corner-to-corner diagonal measurements.
- • Clean, circular footing holes excavated to consistent depth below frost line.
- • Failing to dig deep enough to clear the frost line.
- • Skipping diagonal measurement checks before digging.
Set Support Posts and Pour Concrete
Place post bases or set 4x4 posts directly into the footing holes. Hold a 4-foot spirit level against two adjacent faces of each post to ensure plumb alignment while adding concrete. Pour concrete around the base, tamp out air pockets, and allow it to cure fully.
- • Posts standing completely vertical on both axes with temporary 2x4 bracing stakes attached.
- • Concrete sloped slightly away from the post base to shed water.
- • Plumbing only one side of the post.
- • Pouring concrete dry without mixing or tamping thoroughly.
Mount the Beams to Support Posts
Mark the top cut-off height on your posts using a level, then trim posts flat with a circular saw. Notch the posts or mount galvanized post-cap brackets to seat your double 2x8 support beams. Fasten the beams through the brackets or posts using structural screws or through-bolts.
- • Beams resting flat inside metal post caps or post notches with no gap under the wood.
- • Spirit level reads dead level across the full length of the beam span.
- • Relying solely on lag screws to hold beams in shear rather than resting beams directly on post shoulders or rated brackets.
- • Failing to crown lumber facing upward.
Install Rim Joists and Field Joists
Attach the perimeter rim joists, squaring the outer frame with diagonal measurements. Mark joist locations at 16 inches on center along the inside of the rim joists. Fasten metal joist hangers and slide the 2x8 field joists into position, securing them with approved structural hanger fasteners.
- • Joists evenly spaced at 16-inch intervals with flush top edges.
- • Every nail or screw hole in the metal joist hangers filled with rated hardware.
- • Using standard drywall or deck screws instead of code-approved structural hanger nails or screws.
- • Uneven top edges creating a wavy surface for deck boards.
Fasten Decking Boards
Lay the first deck board straight along the outer edge, overhanging the framing by 1 inch. Secure each board across every joist using two exterior deck screws driven flush, maintaining a consistent 1/8 to 1/4-inch drainage gap between parallel boards. Stagger end joints across different joists if your deck is wider than a single board length.
- • Uniform 1/8-inch expansion gaps visible between all adjacent boards.
- • Screw heads driven slightly below the wood surface without splitting the grain.
- • Butting wet pressure-treated boards too far apart (they will shrink and create excessive gaps).
- • Driving screws too close to the board ends without pre-drilling, causing splits.
Snap Chalk Line and Trim Overhangs
Snap a single straight chalk line along the wild ends of the deck boards to match your desired overhang. Set your circular saw blade depth slightly deeper than the board thickness and make one continuous cut along the line. Seal all raw cut ends with an exterior end-cut wood preservative.
- • A perfectly straight cut edge across all board ends running parallel to the rim joist.
- • End-cut wood preservative visibly coating all freshly exposed end grain.
- • Setting saw blade depth too deep, accidentally slicing into the framing joists beneath.
- • Wandering off the chalk line during the cut.
Credit: inspired by an original tutorial by KWC Handyman Services — watch the original on YouTube.
Don’t have everything?
- No Post hole digger or auger? Round-point trenching shovel and digging bar
- No Chalk line? Clamped straightedge board and pencil line