How to Build Wooden Deck Stairs

Wooden Deck Stairs

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Overview
  • Working Time: 4 - 6 hrs
  • Total Time: 1 - 2 days
  • Skill Level: Intermediate
  • Estimated Cost: $200 to $400

Your home's deck provides instant access to the great outdoors. Whether you use it for barbecuing, socializing with friends, or for relaxing by yourself, your deck is a valuable addition to your home and property. 

Safely and efficiently accessing your deck is just as important as the deck itself. Learn how to build wooden deck stairs easily by using pre-built stair materials found at your local home center, along with basic tools that you may already have on hand.

Basics of Building Wooden Deck Stairs

Deck stairs and their related items such as railings and balusters must be built according to local building code. Stairs risers must reach to a certain height (usually 7-3/4 inches, maximum) and treads, the horizontal part of the stair that you step on, must be of a certain length (10 inches, minimum). Along with the stair balusters and railings, this is all regulated by code for the safety of the stair users.

Instead of building the stairs from scratch, the easiest and often best way is to use pre-built stair materials for some of the more crucial parts that must meet code. One especially valuable pre-built item is the stair stringer.

Stair Stringers

Stair stringers are the notched boards that form the two sides and center of the stairs on which the treads rest. Most home centers carry stair stringers ranging from two-step to eight-step, depending on your needs. 

With the 6-3/4-inch rise and 10-inch tread depth built into the stringer, you won't need to worry about meeting code. Just be sure to buy one stringer for each side and another for the center. Since this is for the outdoors, you'll need pressure-treated ground contact rated wood.

Stair Treads

Treads are the steps, the horizontal part of the stairs that you step on. Two six-by-six boards installed next to each other form a tread. Since the true dimension of a nominal 6-inch-wide board is 5-1/2 inches, it’s perfect for the 10-inch depth built into the stringer.

Tip

Check on your local code about whether the stair risers must be covered; that is, filled in with another board in the back. The risers in this project are open.

What You'll Need

Equipment / Tools

  • Circular saw
  • Tape measure
  • Pencil
  • Cordless drill
  • Hammer
  • Speed Square
  • Plumb bob or laser level
  • Scrap piece of two-by-four

Materials

  • 3 stair stringers
  • 3 galvanized adjustable stringer connectors
  • Six-by-six pressure-treated lumber
  • Two-by-four pressure-treated lumber
  • 10d galvanized nails, 1-1/2-inch
  • Copper-based wood preservative

Instructions

  1. Measure the Correct Stringer Length

    Measure from the deck’s rim board to the ground. The correct stair slope is usually 40 degrees. To determine slope, use the Speed Square held against the scrap piece of two-by-four, along with the plumb bob or laser level. Mark the spot on the ground where the stairs will end. 

    If any of the stair stringers available for purchase perfectly hit the mark, purchase that set. Otherwise, buy the next-longer size. Longer stair stringers can be cut down to size.

  2. Mark the Stringer Positions on the Rim Board

    Measure and mark 36 inches across on the deck rim board where the stair stringers will be attached. Add a third mark in the middle at 18 inches.

  3. Attach the Stringer Connectors

    Attach the stringer connectors to the three marks that you made earlier. The middle connector will be attached on-center. The two side connectors will meet the marks on the sides so that the entire width is 36 inches. Attach with 16d nails.

    Tip

    The galvanized stringer connectors are sold flat, but you will bend them to the desired angle. For an even stronger connection, you may opt to use 1 1/2 inch strong-drive SD screws.

  4. Attach the Plate to the Footer

    Cut the two-by-four to 36 inches. Attach this to the bottom (or footer) as a plate to receive the bottom ends of the stringers. The method of attaching the plate to the footer depends on the footer material. If the footer is wood, use heavy-duty screw anchors.

  5. Attach the Stringers

    Attach the stringers to the three connectors. Bend the connectors upward to match the slope of the stringers.

  6. Attach the Stringers to the Plate

    Attach the bottoms of the stringers to the plate with the four framing angles.

    Tip

    Any pressure-treated wood that is cut must be treated on the cut area with wood preservative. Copper-based wood preservative is inexpensive and can be found at your local home center.

  7. Cut the Stair Treads

    Cut the stair treads to 36 inches long. Cut two boards per tread.

  8. Attach the Back Stair Tread

    Nail or screw the stair treads to the stair stringers. Butt the rear board against the back of the notch, then attach it.

  9. Attach the Front Stair Tread

    Leave a 1/2-inch space between the back and front stair treads. Next, attach the front stair tread. This leaves a slight overhang, called a nosing.