wikiHow to Build Deck Stairs

You normally don't give much thought to building a set of deck stairs. But, when the time comes, you should check out Internet sites for advice or attend a DIY clinic at your local home improvement store. This and the tips provided below will help you build deck stairs and gain easy access to a tall wooden porch.


  1. Image titled Build Deck Stairs Step 1
    Include certain basic or nominal features, such as a minimum width of 48 inches (1200 mm), tread of 10.5 inches (275 mm), and a height of the riser or step of approximately 7-to-8 inches (175-to-200 mm) in your design. The stair stringers should not be more than 16 inches (400 mm) apart. Set the foot on either a 6 x 6-inch (150 x 150 mm) treated wood timber or roofing paper (if set upon concrete) to prevent rot.
    • Ideally, the stair tread should be built from a composite wood material designed for exterior decking for its durability.
  2. 2
    Measure the height of the stair from the bottom of the decking -- or top of the floor joist -- to the ground and then divide by the 7-to-8 inches (175-to- 200 mm). This will give you the number of steps you will need to make.
    • Adjust the height until the height and steps balance out (since you can't have a half or quarter of a step). Take the number of steps and multiply that by 10.5 inches (266.7 mm). That gives you the length of stair stringer necessary. Take that length and project it out from the deck. Now you have the location for the footing of the stair.
  3. Image titled Build Deck Stairs Step 3
    Lay out the steps on the stringer, using 2 x 12-inch (50 x 304 mm) treated wood, with a framing square. Set the riser for the height determined by your math and the step by 10 inches (250 mm).
  4. Image titled Build Deck Stairs Step 4
    Cut the riser and steps out with a circular saw, but stop just short of cutting through. Use a hand saw to finish the cut.
  5. Image titled Build Deck Stairs Step 5
    Install the stringers by attaching them at the top of the deck outside the framing using metal floor joist hangers. Establish the riser boards using 1-inch (25 mm) thick treated wood screws beginning at the bottom riser.
    • Stringers and risers put into place begin with installation of the treads using composite wood designed for decks (best used for durability and strength). This decking, made from specially prepared compressed wood particles comes in what is referred to as 5/4 thickness. This is 1.25 inches (32 mm) thick and comes in variable widths. Secure all with 3" (75 mm) deck screws.


  • Composite wood decking may require pre-drilling for ease of screwing down the decks.
  • Keep checking that the stringers are plumb and square to the deck.
  • Place the decking with any cupped boards face down to prevent tripping.


  • The biggest enemy of a deck or deck stairs is moisture. Use weatherproofing stain as soon as possible. Use some kind of asphalt membrane - like tar paper - to set the stringers on when setting the foot of the stairs on concrete. This will deter dry rot.

Things You'll Need

  • 3-inch (75 mm) deck screws
  • 2 x 12 (50 x 300 mm) treated wood for stringers
  • Metal floor joist hangers
  • Treated wood for risers
  • 5/4 wood composite decking width
  • Circular saw
  • Hand saw
  • Cordless screwdriver
  • Hammer
  • Framing square

Article Info

Categories: Walls Fences and Decks