What Goes Into a Deck
A deck is fourteen line items: six structural, two for the stairs, three for the railing, and three for hardware. Most people price the decking, see a number they like, and get surprised at the register — the frame underneath routinely costs as much as the boards on top, and the footings are a separate trip for concrete entirely. Stairs and railing are the next surprise after that. This list sizes all of it from the measurements you already have: the finished deck size and its height above grade.
Every line traces back to its standalone calculator, so you can adjust any single number and see the effect. The board count comes from the Deck Board Calculator, the framing from its built-in framing estimate, and the pier concrete from the Concrete Calculator using its column shape — the same math, not a lookalike.
A Worked Example: 16 × 12 Attached Deck
A 16-foot-wide deck projecting 12 feet out from the house is 192 square feet, and the defaults on this page produce:
- 29 decking boards at 16 ft (5.5 in wide, 1/8 in gaps, 10% waste)
- 13 joists at 16 in on center — about 156 linear feet of joist stock
- 32 linear feet of beam stock across 2 beams
- 56 linear feet of ledger plus rim and band board
- 6 posts at 8 ft on center along the beams
- 0.67 cubic yards of concrete — about 31 eighty-pound bags — for six 12-inch piers 42 inches deep
At 36 inches above grade with a guard on the three open sides, it also takes:
- 3 stair stringers at 4.61 ft each — 5 risers of 7.2 in, 4 treads
- 24 linear feet of stair tread board
- 8 railing posts, 80 linear feet of top and bottom rail, and 96 balusters
- 13 joist hangers, 13 ledger fasteners, and 676 deck screws
That last line is the one worth staring at. Thirty-one bags is roughly 2,500 pounds of concrete to mix by hand for a deck most people think of as small. Once you are past about a cubic yard, price a short-load ready-mix delivery before you commit to a weekend with a mixing tub.
The Two Inputs That Change Everything
Footing depth is set by your local frost line, not by preference. A pier that stops above the frost line will heave, and a heaved pier racks the whole frame. Forty-two inches is a cold-climate default; your building department has the real number, and that number roughly doubles your concrete if you guessed low.
Joist spacingis set by what you are walking on. Sixteen inches on center is the standard for dimensional lumber run perpendicular to the joists. Composite decking and any diagonal board layout usually need 12 inches on center, which adds roughly a third more joists and more hangers with them. Check your decking manufacturer's span rating before you frame, not after.
The joist span figure behind the beam count deserves the same caution. This calculator uses a 10-foot planning span to decide when a second beam becomes necessary. A real 2x8 southern pine joist at 16 inches on center spans closer to 13 feet, and a 2x6 closer to 9 — look up your actual joist size, species, and grade in the DCA 6 span tables before ordering beam stock.
Stairs Divide, They Don't Round
Every riser in a run has to match the others within 3/8 inch, so the height is divided evenly rather than rounded step by step. A leftover short step at the bottom is both a trip hazard and a code failure, and it is the classic mistake on a first stair build.
The riser count here also respects the 7.75-inch maximum by construction, not by warning you afterwards. Rounding a 24-inch rise to a 7-inch target gives 3 risers — but that is 8 inches each, over the limit. The stair gains a riser instead and lands on 4 at 6 inches. Tread depth stays a separate check, since a tread under 10 inches is flagged rather than silently corrected.
Treads come out one fewer than risers, because the deck surface is the top landing. Stringer stock follows the hypotenuse of rise and run, so it is always longer than either — order to the diagonal, not the drop.
What This List Does Not Include
Budget separately for ledger flashing and lag or through-bolt hardware, post bases and structural connectors beyond the joist hangers, stair railing and graspable handrail, a concrete landing pad at the bottom of the stairs, and hidden fastener clips if you use them instead of face screws. The screw count assumes two per board at every joist crossing; hidden clips are priced per square foot instead.
Ledger attachment and flashing are also where most DIY decks actually fail. A deck that separates from a house almost always does it at the ledger, so that connection is worth doing by the book — and it is the detail your permit inspection will look at first.
Export Your List
Use the buttons above the article to copy the list, download a PDF, or email it to yourself. When supplier links are configured, the “Send this list to Home Depot” section opens a live, in-stock search for every line item — one click per material.
Related
- Deck Building Guide — step-by-step build
- Deck Board Calculator — just the boards and framing
- Concrete Calculator — footings on their own
- Setting Posts in Concrete — pier and post technique
- Room Finishing Materials List — the indoor equivalent
- All project materials lists
Written by Daniel McCarney — AceCalc