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How to Attach Deck Railing Posts to Joists

by Nikki Fotheringham

Appropriate guards around decks are there for safety, and in many areas are required through the local building code. The building code often stipulates the exact minimum height and design of these guards and should be followed at all times. Securing the railing posts to joists properly will ensure your railing is steady and strong. By using some commonly available tools you can ensure that your railing will last a long time.

Mark each joist where you will install a post using your pencil. Determining the location for each railing post will depend deck configuration and the requirements of the local building code. Make a vertical line at each location on the joist using a measuring tape to check that they will be evenly placed.

Mark the pilot holes for the post bolts. Mark two holes, centered over the post location and spaced evenly apart from the top and bottom edges of the joist. You may need to adjust the spacing of the holes depending on the size of the joists and the size of the railing posts used.

Position each post on its layout line and clamp it in place. Drill through the joist and post at the hole markings, using a bit that is the same diameter as the bolts you will use. Keep the drill level and perpendicular to the joist to create straight holes.

Bolt the posts to the joists. Place a washer on a through bolt and push it through the railing post and then on through the joist. Holding the post against the joist, place another washer over the through bolt on the joist side. Thread a nut onto the bolt. Repeat for each of the two holes on each post and each joist.

Tighten the bolts. Using an adjustable wrench on either side of the bolt, turn the nuts inward (clockwise) to secure the railing post against the joist. The post should be firm and securely fastened to the joist at this time. Repeat for all the railing posts. You are now ready to add a railing or guards.

Items you will need

  • Pencil
  • Measuring tape
  • Clamps
  • Drill
  • Eye protection
  • Through bolts
  • Nuts
  • Washers
  • Deck railing posts
  • Two adjustable wrenches


  • Always wear appropriate eye protection when operating power tools.
  • A spirit level can help to make straight lines and ensure that the posts are mounted perfectly vertical.


  • Follow the local building code requirements for all deck post and railing design specifications. Often it's required or advisable to install lumber blocking on both sides of posts that mount to any joists that run parallel to the common joists of the deck structure (typically perpendicular to the house wall).

About the Author

Nikki Fotheringham is a Toronto green living blogger specializing in environmentally friendly building technologies, renewable energy and all things green. She's the copy editor for which dispenses green living advice for urban dwellers. She's traveled the globe, swum with sharks and been bitten by a lion (fact).

Photo Credits

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