September 29, 2026
A 12 x 16 is one of the most common deck sizes: big enough for a table and a grill, small enough for a first build. This page works one through from start to finish with the same numbers Deck Planner gives, so you can see what each decision is and why.
Change any of these and the answers below change. The last two in particular depend on where you live.
The joists span from the ledger on the house to the beam. The beam sits 11 ft out, so the joists span 11 ft and run 1 ft past the beam to the outer rim. For 11 ft, a 2x8 at 16 in apart is within the span table (AWC DCA 6, Table 2, No. 2 Southern Pine at 40 psf). On a 16 ft wide deck that is 13 joists.
If you wanted the beam at the very edge (a 12 ft span), check the table again rather than assuming the same size still works. Deck Planner redoes that check every time you change a number.
One beam carries the outer end of the joists. Here it is two 2x8s nailed together ("2x8 doubled") on four 6x6 posts, 5 ft 4 in apart. That beam size is within Table 3A for 11 ft joists at that post spacing. Fewer posts means a longer beam span and a bigger beam.
Each post sits on a footing. For 11 ft joists and posts 5 ft 4 in apart at 1,500 psf soil, the footing table gives 21 in round (or 18 in square), 8 in thick. The bottom must be at least 12 in below grade, or below your frost line, whichever is deeper. With 21 in form tubes 12 in long, four footings take 9.7 cu ft of concrete, 17 bags at 80 lb. Call 811 before you dig.
The ledger is the board bolted to the house, and it is where decks most often fail. For an 11 ft joist span into a 2x band joist, the table spacing is 1/2 in lag screws with washers every 15 in, staggered: 14 of them along 16 ft. Flash above the ledger with corrosion-resistant metal, and not aluminum against treated lumber. Hang each joist in a joist hanger at the ledger.
With the boards running along the 16 ft side, each row is one 16 ft board with no joints: 26 boards of 5/4x6 and 676 deck screws (two per board at each joist).
At 36 in off the ground, the deck needs a guard (a railing is required over 30 in). On the three open sides that is 10 posts and 80 balusters at 3 1/2 in clear. One 36 in wide stair off the front comes out at 5 risers of 7 3/16 in and 4 treads of 10 in, a 3 ft 4 in run, on three cut 2x12 stringers, with a handrail because there are four or more risers. The stair has its own two small footings.
This is the whole list for the deck above, as Deck Planner makes it.
| Qty | Item | For |
|---|---|---|
| Framing | ||
| 4 | 2x8 x 16 ft | Rim, ledger, beam plies |
| 13 | 2x8 x 12 ft | Joists |
| 2 | 2x8 x 8 ft | Blocking |
| 1 | 6x6 x 8 ft | Four posts |
| Footings and concrete | ||
| 4 | Footings, 21 in round, 12 in deep | One per post |
| 4 | Form tubes, 21 in | 12 in long each |
| 17 bags | Concrete mix, 80 lb | 9.7 cu ft |
| Hardware | ||
| 13 | Joist hangers, 2x8 | At the ledger |
| 130 | Joist hanger nails, 1 1/2 in | 10 per hanger |
| 14 | 1/2 in lag screws with washers | Ledger, every 15 in |
| 16 ft | Ledger flashing | Not aluminum |
| 13 | Joist-to-beam ties | One per joist |
| 4 | Post bases, 6x6 | On the footings |
| 4 | Post caps, 6x6 to 2-ply 2x8 | Or notch the post |
| 2 | Lateral hold-down tension devices | 1,500 lb each |
| 4 rolls | Joist tape, 50 ft | Optional |
| 10 | Guard post hold-downs | 1,800 lb each |
| 20 | 1/2 in through-bolts with washers | Guard posts |
| 2 | 4x4 post bases | Stair posts |
| 2 | End-cut preservative, quarts | Every cut in treated lumber |
| Decking and fascia | ||
| 26 | 5/4x6 deck boards x 16 ft | 26 rows, no joints |
| 1 | 1x8 fascia x 16 ft | Front |
| 2 | 1x8 fascia x 12 ft | Sides |
| 676 | Deck screws, 2 1/2 in | 2 per board per joist |
| Railing | ||
| 5 | 4x4 x 8 ft | Guard posts |
| 4 | 2x4 x 12 ft | Rails |
| 4 | 2x4 x 8 ft | Rails |
| 2 | 2x6 x 12 ft | Cap rail |
| 2 | 2x6 x 8 ft | Cap rail |
| 27 | 2x2 x 8 ft | Balusters |
| 320 | Baluster screws, 2 1/2 in | 4 per baluster |
| Stairs | ||
| 3 | 2x12 x 8 ft | Stringers |
| 4 | 2x6 x 8 ft | Treads, 2 per step |
| 6 | 2x4 x 8 ft | Bearing block, handrail backer, stair rails |
| 1 | 4x4 x 8 ft | Stair posts |
| 8 | 2x2 x 8 ft | Stair balusters |
| 3 | Stringer connectors | One per stringer |
| 2 | Stair footings, 12 in round, 12 in deep | Bottom posts |
| 3 bags | Concrete mix, 80 lb | 1.6 cu ft |
| 6 ft | Graspable handrail | 34 to 38 in high |
How to read each line is on How to read a deck material list.
Open Deck Planner, type 16 for the width, 12 for the depth and 36 in for the height, and you will get this plan drawn to scale. Then change what is different about yours: a lower deck may not need a railing, a free-standing deck swaps the ledger for a second beam, and a colder town needs deeper footings.
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Deck Planner helps you plan and estimate. It is not engineering advice and it does not replace your building department, a licensed engineer or a contractor. Span and footing checks come from the American Wood Council's DCA 6 deck guide (2015 IRC) for typical conditions, and your town may use a different code edition, snow load, frost depth or soil value. Most decks need a permit. Check with your local permit office before you buy materials or build.