How to Build Step Rails on a Deck

A handrail is the best way to prevent people from falling on the steps from the deck to the backyard. Minimal woodworking knowledge is needed to build one. You will only need a measuring tape and a saw to get the correct angle of descent. Use treated lumber even if you are going to seal the rail.

Step rail for a deck
  1. Measure and cut a 4-by-4-inch post 29 inches long for the top and bottom steps. If there are more than five steps, cut a third post to be secured about halfway down.

  2. Secure the post holders in place with 1 1/4-inch deck screws. The post on the bottom step needs to be set against the second tread. Place a carpenter's level vertically against the second step tread and use the plumb bubble so you can mark the bottom step tread. This is where the post holder should be installed.

  3. Install the posts into the holders with the 1 1/4-inch deck screws. Tighten the screws just enough to hold the posts while you determine the angle of descent. Measure down from the back outside corner of the top post and make a mark at 1 1/2 inches. Repeat this for the front outside corner of the bottom post.

  4. Place the end of the chalk line on one of the marks, stretch it to the other mark and pop a chalk line on the side of the posts. Remove the posts, cut them on the angle with the electric miter saw and solidly secure them back into the post holders with the 1 1/2-inch deck screws.

  5. Measure from the top post to the bottom post and add 12 inches. Mark and cut a 2-by-4 at this length and secure it to the tops of the posts, allowing it to hang 6 inches past the posts. Secure it to the tops of the posts with 3-inch deck screws.


  • Do not leave power tools unattended in the presence of children. Wear safety glasses when cutting lumber.

About the Author

Michael Straessle has written professionally about the construction industry since 1988. He authored “What a Strange Little Man,” among other books, and his work has appeared in various online publications. Straessle earned a Bachelor of Arts from the University of Arkansas at Little Rock in professional/technical writing.