Building a deck is a sequence of structural layers, each carrying the one above it: footings into the ground, posts and beams on the footings, joists across the beams, and decking on top. Get the spacing and connections right and the rest is repetition.
The build sequence
Set concrete footings below the frost line, anchor posts with metal post bases, set the beams, then attach a ledger board to the house (flashed and lag-bolted into the rim joist — the connection where most failed decks start). Hang joists off the ledger and beam with joist hangers, typically at 16 inches on-center, then fasten decking perpendicular to the joists with a small drainage gap.
Spacing that matters
| Element | Typical spacing |
|---|---|
| Joists | 16″ on-center (12″ for diagonal decking) |
| Footings / posts | 6–8 ft along beams |
| Decking gap | ~1/8″ for drainage |
Joist span depends on lumber size, species, and spacing, so check a current span table or local code rather than guessing. Use pressure-treated, ground-contact-rated lumber for the structure.
Frequently asked questions
How far apart should deck joists be? 16 inches on-center for most decking; 12 inches for diagonal boards.
Do I need a permit? Almost always for attached decks — check before you dig.