Deck planning guide · 5 min readUpdated
Lay out deck joists, beams, posts and footings
Generate supports from the actual deck outline, position flush or dropped beams, and read clear spans, post stations and backing schedules.
Establish the joist direction and ledger arrangement
Mark house edges in Shape, then open Framing. Create framing layout adds the framing layer. For patterned decking, first set the support target in Decking and use Recalculate framing.
Ledger attachment controls whether marked house edges are structural ledger lines or the deck is treated as freestanding. A house edge parallel to the joists does not automatically support their ends. Enter joist, beam, post and footing sizes from the project design; the tool does not choose them.
Choose the right update action
| Action | What it changes | What to review |
|---|---|---|
| Recalculate framing / Recalculate for decking | Joist grid and pattern backing; adds beams only when none exist | Existing beams and posts are retained, even if joist direction changes |
| Generate beams from joists | Replaces beam rows and post positions using the outline, ledgers and bay target | Review all supports and footing positions; Undo restores the earlier layout |
| Apply cantilever | Moves eligible perimeter dropped beams and their posts | Flush and interior supports stay in place; check every flagged end |
Generate beams from the real outline
Set Target clear joist bay to the layout distance you want to work toward, then choose Generate beams from joists. Perimeter supports follow relevant deck edges, including angles, and deeper bays receive intermediate rows. Recesses split paths where there is no deck.
Generation uses dropped beams and retains entered lumber sizes on matching paths where possible. The bay target is a layout preference, not an allowable span. The generator has a 12-row limit; support warnings still need review on complex shapes.
Set a beam’s mount and path
Dropped beams sit below continuous joists. Flush beams are at joist level and trim crossing members at the beam faces. Use Beam path to choose Straight row across the plan, Follow a deck edge, or Custom endpoints / angle.
A dropped beam’s edge inset is measured to its centreline. A flush beam’s Outside face inset from edge measures to its outer face; set it to zero to align with the perimeter. For a custom path, enter start/end X and Y or drag the end handles. Angled path lengths and post stations are measured along the beam.
Position posts and footings
Even spacing balances posts along each beam segment using the target maximum O.C. and the inset from each end. Dragging a post switches that row to manual positions. Enter each post centre keeps explicit stations along the beam; a point inside a recess or outside the beam is flagged.
Posts and footings move with their beam. Choose the post size, footing shape, diameter or width, and base depth below grade. The model uses those dimensions for the layout and view; it does not establish soil bearing, frost protection, footing construction or post connection details.
Add backing and read the schedule
Picture-frame backing follows the selected border edges. Solid blocking rows span the joist bays. Guard backing and seam backers are editable runs, while stair-opening backing follows valid stair openings. Pattern backing follows internal board ends and splices.
Select a joist in Framing plan to read clear spans between support faces and end overhangs beyond the outer support face. Select a beam for post spacing and beam end overhangs. The printed schedule lists members and post/footing coordinates; net framing runs are separate from the priced decking order.
Review the layout after changing the outline, board pattern, joist direction, beam mount or member sizes. Edge-linked beams can follow a resize; fixed rows and custom endpoints retain entered coordinates. A rendered support arrangement is not a structural design.