Plan an L-shaped deck and picture-frame border

Use the border to resolve an edge

A picture frame can cover the appearance of field-board ends and give the deck a deliberate perimeter. It is especially useful where those ends would be prominent beside stairs or an exposed edge. It needs its own support and fastening detail; it is not trim that can simply hang past the last joist.

Bordering only exposed edges uses less border stock and can keep a narrow leg of an L-shaped deck more open visually. A full border can make the field feel contained, including along the house, but adds joints and reduces the field width. At an inside corner, check how the courses meet before committing to two border rows.

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

Draw a more complex footprint

Choose which edges receive the picture frame

Choose one or two border rows and enter the actual face width. In the board calculator, match the perimeter letters to Border these edges. In the Deck Designer, Exposed edges follows the marked house sides, Full perimeter includes them, and Custom edges lets you choose each edge separately.

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

The board calculator keeps its entered joist grid fixed when the board direction changes. In the Deck Designer, changing straight Board direction also turns the joists; Recalculate framing updates the grid and pattern backing. Existing beam positions remain for review until you edit or regenerate them.

Straight, angled and herringbone decking are supported. Use the Deck Designer to lay out backing at border seams and pattern joints, then verify spans, bearing and connections for the actual materials. Breaker-board layouts and structural design are separate.

Match a decking pattern to its framing