Plan an L-shaped deck and picture-frame border

Measure one footprint

Use the largest outside rectangle that contains the deck, then measure the rectangular corner that is missing. Choose the matching corner in the plan: top left, top right, bottom left or bottom right. These are drawing directions, not compass directions.

For example, a 12-by-10-foot overall deck with a 4-by-4-foot corner removed has 104 square feet of finished area. Both remaining legs must have positive width. Check the overall dimensions, cutout and inside corner before ordering.

L-shaped area = overall length × overall width − cutout length × cutout width
Example: 12 × 10 − 4 × 4 = 104 ft²

Choose which edges receive the picture frame

Choose one or two border rows and enter the actual face width of the border board. Match the A–F perimeter letters in the diagram to the edge checkboxes. You can leave a house edge unbordered instead of forcing a frame around every side.

Selected borders occupy space inside the finished outside dimensions. The planner moves the field inward by the border widths and gaps, then lays out the field courses in the remaining area. This prevents counting field boards under the frame. Adjacent selected border edges meet with mitres.

• Confirm the intended border profile; an exposed edge may require a square-edge board.
• Check both L-shaped legs remain wide enough for the border and field.
• Provide backing for the picture frame and the field-board ends meeting it.

Read the inside-corner course

Courses continue across the combined field instead of being counted independently as two overlapping rectangles. A course crossing the inside corner may require a notch. Its listed blank size is the full rectangle needed before that notch is removed.

Select the numbered piece or open the cut list for its notch dimensions. Horizontal and vertical dimensions refer to the top-down plan, and the named corner identifies the material to remove from that blank. Confirm the return against the actual framing and provide its required support.

Order field and border stock separately

The purchase list and cutting sheet keep field and border profiles apart. A long-point mitre blank is the rectangular stock length needed to form the corner; the final installed mitre and corner gap are fitted on site. Where a border needs a splice, add and verify its backing.

Compare each available length with the mixed plans. A longer board may eliminate a joint, while a mixed order may fit shorter pieces with less leftover stock. Complete all prices to compare the quoted material totals, then review the separate spare-board quantities.

Keep the joists tied to the actual deck

Turning the field boards does not turn the joists. Use the joist overlay to check the entered direction, spacing and first offset. Field joints are assigned to that grid where possible; backing for border pieces and field ends remains a separate detail.

The planner does not add structural capacity. Confirm permitted decking spans, joint bearing, fasteners, blocking and the framing design for the selected material and layout. Diagonal patterns and breaker-board layouts are outside this version.