How to Build Box Steps for a Deck

If you are preparing to build stairs for your deck but are worried about cutting the stringers (the sloped lumber that supports stair treads), then box steps may be a good alternative. They can be less intimidating for most do-it-yourselfers because there are no stringers to cut. Instead, box steps utilize two solid outer stringers with face mounted "ledges" to support the treads.

  • Tape measure
  • Calculator
  • Pencil
  • Framing square
  • 2-inch by 12-inch pressure-treated lumber boards
  • Circular saw
  • Staircase angles
  • Hammer
  • 1-1/2 inch galvanized hanger nails
  • 2-inch by 6-inch pressure-treated lumber boards
  • 2-inch by 8-inch pressure-treated lumber
Measure the vertical distance from the top of the finished deck surface to the top of the finished landing area. Mark this measurement in inches.

Calculate the number of steps needed by dividing this measurement by 7.5 and round the answer to the nearest whole number.

Divide the vertical distance by the number of steps required. This will give you the height of each stair riser (the vertical board between two stair treads). Round to the nearest 1/8th inch.

Place your framing square onto a 2-inch by 12-inch pressure-treated board. Locate the riser height on one leg of the square and the desired tread depth on the other leg. Align these points with the board's edge simultaneously.

Trace the tread line onto the lumber, slide the framing square down the board's edge so that the riser height aligns with the tread line, and draw the next tread line. Repeat this process for as many steps as you require. For the last stair step, draw the final riser height and a line perpendicular through the back of the stringer.

Cut away the final riser height and perpendicular line with your circular saw.

Draw a line perpendicular to the back of the top step line and cut this line with your circular saw. Discard remnant material.

Repeat steps 4 through 7 for the opposite stringer. Work on the opposite edge of the board for the second stringer.

Align and fasten staircase angles at each tread line so that they form a ledge. The side of the staircase angle flush with the stringer must face downward.

Nail two 2-inch by 6-inch pressure-treated lumber boards to the staircase angle ledge and repeat on the opposite stringer (be sure to nail to the same step's ledge). Do this for all treads.

Attach a 2-inch by 8-inch pressure-treated lumber board (riser) so that its face is against the back of a step (forming an "L") and its top is firmly against the bottom of the step above, and nail in place. Repeat for all risers.

Attach completed box steps to deck.

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