Deck project planner
Size a deck and get the whole plan: bill of materials, a cost band with the spread shown, the permit answer, and what hiring it out would run.
Composite costs roughly three times what pressure-treated does up front and asks for nothing afterwards. Pressure-treated wants cleaning and re-sealing every two or three years — budget the stain, not just the boards.
Materials at ±12% and the permit fee at ±50% give this spread. The contractor column is wider, at ±25%, because bids vary more than lumber does.
- Plus 64 hours of your time — about 5 weekends with a helper.
- Materials, tool rental, and the permit fee if one applies.
- You need: a post-hole auger, a circular saw, a helper for the beam.
- All-in installed price — their materials, crew, and cleanup.
- Two to four days on site once they start.
- They pull the permit and carry the liability.
Building the deck yourself keeps $4,182 — 62% of the contractor price — and costs you 64 hours. That is $65 an hour for your weekends. Get one quote anyway; it costs nothing and it tells you whether this estimate matches your market.
- The deck is attached to the house. The IRC exemption covers free-standing decks only, so a ledger-attached deck falls outside it whatever its size.
- The walking surface is more than 30 in above grade, which is past the exemption ceiling and also the height at which guards become required.
- The deck serves a required exit door, which the exemption specifically excludes.
| Item | Qty | Unit | Line |
|---|---|---|---|
| 2×8 PT joists, 12 ftcheck ↗ | 13 boards | $18.60 | $242 |
| 2×8 PT beam plies, 16 ftcheck ↗ | 2 boards | $24.80 | $50 |
| 2×8 PT rim & band boards | 3 boards | $24.80 | $74 |
| 2×8 PT ledger, 16 ft | 1 board | $24.80 | $25 |
| 6×6 PT posts, 8 ft | 3 posts | $35.20 | $106 |
| Footing form tubescheck ↗ | 3 tubes | $14.50 | $44 |
| Concrete mix, 60 lb bagscheck ↗ | 21 bags | $6.25 | $131 |
| Galvanized joist hangers | 26 hangers | $1.85 | $48 |
| Pressure-treated decking boards, 16 ftcheck ↗ | 29 boards | $21.60 | $626 |
| Deck screws | 676 screws | $0.05 | $34 |
| Guard rail — posts, rails, balusterscheck ↗ | 37 linear ft | $16.00 | $592 |
| Stair stringers, treads & risers (4 stringers)check ↗ | 5 steps | $38.00 | $190 |
| Materials subtotal | $2,161 |
Prices look wrong for your area? Edit them
Editable estimate · US national averages reviewed July 2026. Prices move; these are a starting point, not a quote. Every edit updates the totals, the band, and the link you share.
- 01Layout & utility locate4 h
Call 811, square the footprint with batter boards and a 3-4-5 check, mark footing centers.
- 02Footings8 h
Dig 3 holes to 4 ft, set tubes, pour, and let them cure before loading.
- 03Ledger, beam & joists17 h
Flash and bolt the ledger, set posts and beam, hang every joist square and crowned up.
- 04Decking13 h
Lay boards from the house out, gap consistently, and cut the outside edge last.
- 05Guard rail9 h
Set rail posts, run top and bottom rails, then space balusters under 4 in.
- 06Stairs11 h
Cut 4 stringers off one template, pour or set the landing pad, hang and tread.
- 07Fasten-off, inspection & cleanup4 h
Hardware check, final screws, inspection walk-through, and haul-off.
64 hours total — about 5 weekends for two people at 14 productive hours a weekend. Working alone, add roughly half again on every phase that needs a second pair of hands.
A deck is four jobs stacked on each other, and the estimate falls apart if you price only the visible one. Underneath the boards you can see are joists at 12, 16, or 24 inches on center, a beam carrying them at the outer edge, posts under the beam at eight feet or less, and a footing under every post reaching below your frost line. This planner sizes all four from two dimensions and a height, using the prescriptive layout in the American Wood Council's DCA 6 deck guide, then adds guards and stairs when the height requires them.
The permit answer comes from the model code rather than from a guess. The 2021 IRC exempts a deck from a building permit only when it is under 200 square feet, no more than 30 inches above grade, not attached to a dwelling, and not serving a required exit door — all four at once. Change any one of those and the exemption stops applying, which is why a small deck bolted to the back of a house still needs a permit while a larger free-standing platform in the yard may not. Your jurisdiction can amend those thresholds, so the page reports a likelihood and the reason behind it, never a determination.
Cost is shown as a band because a single figure would be a lie about precision. Material prices move with commodity cycles, so the bill of materials carries a spread of plus or minus 12 percent. Contractor bids on the same scope commonly differ by 20 to 30 percent, so the installed column carries plus or minus 25. The regional multiplier is applied separately to each, because lumber is a shipped commodity that costs roughly the same everywhere while labor is not. Every price is editable, and the totals, the band, and the shareable link all update the moment you change one.
The last number is the one that decides things. Building a deck yourself saves real money, but it costs a measured number of hours, and the planner divides one by the other to show what your weekends are actually earning. On some decks that figure is high enough to make the choice obvious. On others it is not, and the page says so.
area = 16 × 12 = 192 sq ft
joists = ceil(16 ft ÷ 16 in) + 1 = 13 joists at 12 ft
posts = ceil(16 ft ÷ 8 ft) + 1 = 3, footings 12 in × 48 in
concrete = 3 × π × (0.5 ft)² × 4 ft = 9.42 cu ft ÷ 0.45 = 21 bags
decking = ceil(144 in ÷ 5.6875 in) = 26 courses × 1.10 = 29 boards
guard = 36 in > 30 in, so required: 40 ft perimeter − 3 ft stair = 37 ft
stairs = ceil(36 in ÷ 7.75 in) = 5 risers at 7.2 in, 4 stringers
permit = attached + over 30 in + serves the exit ⇒ likely required