How to Build a Strong Deck
- 1). Dig your post holes a minimum of 24 inches deep to provide a sound footing. Consult local building codes for specific details. Also check with your local department of agriculture and install your footings below the frost line to prevent their being uprooted in a hard freeze. Use 4-by-4 treated lumber posts to prevent premature rot. Pour concrete footings a few inches below grade and top fill with soil for proper drainage. Mark and cut your posts to length with a reciprocating saw after frame is attached.
- 2). Install your outside rim and frame lumber using joist hangers and steel corner ties. Attach all hangers with treated deck screws. Drive the screws with a cordless drill. Use all of the available screw holes in the hangers to ensure the strongest joints.
- 3). Notch posts where they meet framing members to cradle the post and provide support vertically, using a circular saw and hammer and chisel. Bore bolt holes the same size as your bolts for a tight fit. Bolt through the posts and tighten with nuts using a socket wrench. Use large fender washers and only galvanized hardware to prevent rusting.
- 4). Hang one joist every 16 inches for standard deck. Space joists every 12 inches when using composite material or adding heavy elements such as hot tubs. Use at least 2-by-8 lumber for outside rims and a minimum of 2-by-6 for joists. Consult a timber strength chart, from your lumber retailer, for the correct dimensions in situations where you will be adding a lot of weight.
- 5). Screw, rather than nail, your treated lumber or composite decking in place. Keep proper spacing, typically 1/8 inch between rows, to promote drainage and prevent rot. Do not countersink screws; run them flush with the face of the decking to prevent water pooling in the screw holes and deteriorating your hardware. Always stagger the ends of boards from row to row and make every joint in the middle of the framing member below.
- 6). Run posts up through the deck to support railings where practical. This allows the footing, rather than a screw, or bracket, to be the rail support. Use heavy, treated hardware brackets where running the posts through is impossible. Add both top and bottom horizontal rails between railing posts for added strength. Screw all joints, rather than nailing.
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