Fit check
Key measurements
Plans heights from the ground · the house is at the back
Front elevation
Side elevation — from the left
Top view — decking
Framing plan
Stringer layout
Posts & footings
Cut list
Lumber list & cutting diagrams what to buy, and what gets cut from each board
Estimated cost approx. Home Depot retail — click a price to match your store
Hardware & concrete
Build steps
Plan a raised wood or composite deck
Deck Planner designs a raised deck the way a deck builder would: pick a shape — rectangle, L-shape, wraparound, clipped corners or two levels — set the height and size, and it lays out the ledger, joists, beams, posts and footings from typical deck span tables, with cantilevers, drop or flush beams and knee bracing on tall posts. Add stairs off any outside edge, with a landing where they need one, choose straight, diagonal or picture-frame decking and one of eight railing styles. The 3D model, framing plan, stringer layout, cut list with cut angles and cost update as you type.
1. Shape & size
Pick a shape, then the width along the house, the depth and the height of the deck surface.
2. Framing
Choose joists, spacing and cantilever. Beams and post spacing are sized for you, and the fit check flags anything past the span tables.
3. Stairs & rails
Add stairs to any outside edge — tall decks get a landing — and pick a railing style.
4. Build it
Download a PDF with drawings, the framing plan, stringer layout, cut list, lumber and hardware to buy, and build steps.
Frequently asked questions
How far can deck joists span?
Roughly, pressure-treated 2x8 joists at 16 inches on centre span about 12 to 13 feet, 2x10 about 16 feet and 2x12 about 18 feet at 40 psf live load. Check the span tables your building department uses — they depend on species, grade and spacing.
How far apart should deck posts be?
It depends on the beam: a doubled 2x10 beam carrying 10 foot joists spans about 7 to 8 feet between posts, a tripled 2x12 closer to 10 feet. Longer joist spans load the beam more, so the posts get closer.
When does a deck need a railing?
Under the IRC, any deck surface more than 30 inches above the ground needs a guard at least 36 inches high with openings under 4 inches. Stairs with four or more risers need a graspable handrail.
When do deck stairs need a landing?
A single flight of stairs can rise at most 12 feet 7 inches (147 inches). Taller decks need an intermediate landing at least as wide as the stairs and 36 inches deep — which is also a good place to turn the stairs.
How far can a deck cantilever past the beam?
A common rule is up to a quarter of the joist span, and no more than about 2 feet for 2x10 joists. Cantilevering hides the beam and posts a little further under the deck.
Is the Deck Planner free?
Yes. It runs in your browser with no sign-up, and you can download the plans as a PDF or save your settings to a file.