Deck planning guide · 4 min readUpdated
Plan angled and herringbone decking with matching framing
Choose straight, angled or herringbone boards, calculate support spacing, and rebuild the joint backing without losing track of beam positions.
Choose a pattern and its dimensions
Open Decking and choose Straight, Angled or Herringbone. Straight boards run Across or Front to back. Angled boards use a measured angle from across the deck: 90° runs front to back, while 45° and 135° give opposing diagonal directions.
Herringbone uses square-ended blocks meeting end to side at right angles. Full block length sets the untrimmed pattern pieces; boundary pieces are cut to the outline. Pattern direction rotates the arrangement. It is not a chevron pattern with mitred ends.
| Pattern | Main setting | Gap treatment |
|---|---|---|
| Straight | Board direction | Side gap between courses; butt gap at splices |
| Angled | Board angle, 1–179° | Side gap between courses; butt gap at splices |
| Herringbone | Pattern direction and full block length | Side gap around each block |
Set the decking support target
Enter Support-spacing target along boards from the requirements for the chosen decking and installation. This measures support-to-support distance along the board, which differs from the perpendicular joist-grid spacing when a board is angled.
The designer shows Calculated joist centres and Current support distance. Recalculate framing chooses a compatible joist direction where needed and rounds its calculated spacing down to a quarter inch. It does not select a structural joist size or approve a manufacturer’s span.
45° board crossing front-to-back joists: Along-board support distance = joist spacing ÷ cos(45°) Example planning target: 16 in along the board 16 × cos(45°) = 11.31 in joist centres Designer rounds down to 11.25 in
The 16-inch target demonstrates the geometry. Use the span and fastening requirements for your actual decking product and orientation.
Recalculate joists and backing, then review beams
Press Recalculate framing in Decking, or Recalculate for decking in Framing. The joist grid and first offset change to match the support target, and internal joint backing is enabled. If there are no beams, an initial beam layout is generated.
Existing beams, posts and footing locations stay in place during this recalculation. If the joists change direction, those beams may no longer provide the intended supports. Use Generate beams from joists to replace the beam/post layout, or edit its paths yourself. Review the support messages either way.
Inspect board ends and short blocks
In Framing plan, PB labels mark backing under internal pattern joints. Picture-frame backing supports the border seams; it is a separate control. Use 3D view → Framing to see the support arrangement without the decking hiding it.
Inspect short blocks, end bearing, connections and perimeter cuts. A line of backing in the drawing does not specify its fastening or structural capacity. Angled and herringbone patterns do not receive the simple straight-board fastener estimate; count the selected fixing system and joint details separately.
Compare the actual cuts before ordering
Use Numbered cuts & stock comparisons to inspect the patterned pieces, assigned stock boards, joints and spares. Do not estimate an angled or herringbone order by applying the straight rectangular course-count formula to the overall width.
Field and border profiles are allocated separately. Include usable stock length, saw kerf, product-specific gaps and an appropriate spare allowance. Breaker-board layouts, fascia and stair materials remain separate.
Technical references
Confirm the current product literature and requirements for the material and assembly being installed.