How to Build a Handrail for Deck Stairs


A handrail boosts the safety of your deck's staircase. When your deck gets wet in the rain, a handrail ensures people can climb the stairs without slipping and falling. With a little construction know-how, you can complete this project on your own without calling in professional contractors. Your wallet and your deck will thank you.

Things You'll Need

  • Two 4-by-4 posts
  • 2 clamps
  • Wood file
  • 2-by-4 railing cap (same length as staircase)
  • 2 railings, 1-1/16 inches by 3 inches (same length as staircase)
  • 4-inch nails
  • 4 hex bolts, 1/2 inch by 4-1/2 inches
  • Sandpaper
  • Bar level
  • Tape measure
  • Secure the two posts with clamps to the stairs' stringer, which is the portion of the stairs that supports the treads (steps). Place one post at the bottom and one at the top of the staircase.

  • Check with a bar level to ensure the posts are perfectly perpendicular to the ground. Secure the posts to the wood of the stringer using two hex bolts in each post placed vertically and spaced about 2 inches apart.

  • Saw off the tops of the two posts at a 45 degree downward angle and file the post tops with a wood file until perfectly straight. Check with a bar level to determine whether the angle is 45 degrees.

  • Measure the distance between the two posts to determine the length to cut the three railings. The railings should be the same length as the span of distance between the two posts at each end of the staircase.

  • Saw the three railings to the correct length according to the measurements you took during Step 4. Sand the edges of the railings until they're smooth and free of splinters.

  • Install the railing cap by placing the 2-by-4 railing centered on top of the posts evenly. Nail four 4-inch nails through the cap and into each post top.

  • Place the second railing just below the cap on the outer sides of the posts, and secure it with the clamps. The skinny edge of this railing should be flush with the bottom of the railing cap. Nail the railing to the posts using two nails at each end post.

  • Measure 6 inches down from the railing cap and mark it with a pencil. Attach the third railing at these marks using the clamps, and nail it in place with two nails at each end post.

Tips & Warnings

  • Choose wood that matches that of your existing deck and stairs and that is decay-resistant to weather the stress of the outdoors.

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  • Photo Credit deck image by Albert Lozano from
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