How to Build Deck Stairs

Beth Asaff
Building deck stairs

A set of well-built deck stairs is imperative to any deck. Stairs allow access to the deck from the yard as well as from the home, and they allow you to get more use out of the deck. While building deck stairs is not a task to be done in a day, they can be built over the course of a couple of weekends.

Planning Your Stairs

While the style of your deck or your deck railing may vary, stairs are a fairly straightforward design. They can be created out of any hard lumber, including most of the basic wood species used to build decks, like cedar and standard pressure treated wood. The stairs themselves can have an open or closed rise and are given their real style by the type of banister or railing that is attached. To create the most cohesive deck design, this should follow the railing running the perimeter of the deck.

The basic rise of each step will vary based on your measurements, while the tread will measure in at a standard 10 inches. The slope of your stairs depends on the height of your deck.

Calculating Slope

Before constructing your stairs, calculate the slope and number of stair treads needed.

  1. Measure the height of your deck.
  2. Divide this number by 7.5 to get the number of steps required. Round up to the nearest full step.
  3. To determine the rise of each step, divide the height of your deck in inches by the number of stairs. For example, a deck measuring 96 inches in height will have 13 steps, each with a rise of 7.38 inches.
  4. Multiply the number of steps by 10, the basic size of the tread, to get the slope or distance your stairs will extend into the yard.
  5. Mark the yard where the stairs will end. Most stairs are typically 36 inches wide; make two marks, 36 inches apart at the area where the deck will end.

How to Build Deck Stairs

Once you have your measurements in place, begin constructing the stairs themselves.

Materials

  • Shovel or spade
  • Tamper
  • Pea gravel
  • Quick set concrete
  • Trowel
  • Level
  • Three 2- by 12-inch boards
  • Framing square
  • Pencil
  • Circular saw
  • Handsaw
  • 3 angle brackets
  • 3-inch galvanized deck screws
  • One 2- by 6-inch board
  • Masonry anchors
  • Enough 2- by 6-inch boards to cover the treads with two boards per tread, each measuring 38-inches long

Instructions

  1. Find the two areas marked on the ground and dig down about 6 inches, removing all dirt, rocks and debris from the area between them.
  2. Tamp down the bottom of the holes until they are level and fill the bottom with approximately 2 inches of pea gravel. Tamp down again.
  3. Mix fast drying concrete and pour into each hole. Trowel the tops of the concrete pad smooth and check with the level to ensure it is even.
  4. Allow the concrete to cure for 48 hours.
  5. Create the stringers to form the sides of the stairs. Place a framing square at the top corner of one 2- by 12-inch board so that one leg measures the rise and the other measures the tread. Use a pencil to mark the inside angle of the square.
  6. Move the square down to where the pencil marks goes off the board, measure and mark again. Continue until all stairs have been marked.
  7. Return to the first mark made at the corner of the board, and trace a straight line from the corner across the top to create the join for the stringer to the side of the deck.
  8. Use a circular saw to make the cuts into the stringer. Use a handsaw to finish each cut if necessary.
  9. Place the cut stringer onto the other 2- by 12-inch boards and use it as a template to make the necessary marks and cuts.
  10. Rest the bottom ends of the stringers onto the concrete pad and place the top of each stringer against the outside of the deck.
  11. Screw angle brackets to the deck and to the bottoms of each of the stringers using galvanized deck screws to attach each stringer to the deck.
  12. Cut a 2- by 6-inch board so it fits tightly between the two stringers where they meet the concrete pads. Attach the board between the two stringers with deck screws and to the concrete pads with masonry anchors.
  13. Cut the remaining 2- by 6-inch boards to 38-inches in length. Each tread will be created from two, 2- by 6-inch boards nailed to the stringers with a 1/4-inch gap between them.
  14. Push the first board back against the stringer, so that it overlaps by 1 inch on either side.
  15. Use deck screws to attach the board to the stringer on either side.
  16. Position the second board so that it overlaps the stringer by 1 inch on either side and is 1/4 inch in front of the tread behind it. Screw it in place using deck screws.
  17. Continue adding treads until the stairs are covered.
  18. If desired, cover the rise on each stair by cutting one, 2- by 6-inch board to fit across the front of the rise to the exact width of the two, outer stringers.
  19. Position the board on the top back of each tread and use deck screws to attach it to the rise on the stringers.
  20. Extend the same deck railing from around the deck, down the stairs for a cohesive deck design.

Finishing the Deck Stairs

To finish off your new deck stairs, stain them to match the rest of the deck. Be sure to use the same wood and decking materials as the rest of the deck to ensure the color takes evenly and the stairs and deck appear to be one unit. In just a couple of weeks time, your deck will be more functional than ever before.

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How to Build Deck Stairs