how to install deck railing posts, How to Install Deck Railing Posts that Meet Code Requirements

How to Install Deck Railing Posts that Meet Code Requirements

As we discussed in our previous blog, “Do I Need Railing on My Deck?”, deck railing not only enhances the appearance of your deck, but also helps to keep children and pets safe. Whether you’re building a new deck or upgrading an existing one, installing your own deck railing can save you a bit of money if you have the right materials and skillset.

The first step to building a deck rail system is fastening the new deck posts. The posts keep the  railing from wobbling or sagging, so it’s important that they’re installed according to modern building codes. 

In this guide, you’ll learn two methods for installing wooden deck posts, what tools you’ll need, and what deck post accessories you can add to enhance their appearance.

Deck Railing Code Requirements 

Before you begin, check your local building codes so that your new railing meets the necessary requirements. Your local codes will tell you: 

  • How high the railing should be
  • How far apart the balusters should be
  • How to attach your deck posts to the framing  

Even if you’ve installed deck railing before, you may find that the rules have changed in your state. For example, many states now require specialized connectors to attach deck rail posts to the floor frame.

Planning Post Placement 

You’ll want one deck railing post in each corner if you’re attaching the posts to the inside of the frame, or two on each corner if you’re installing them on the outside. The rest should be spaced as evenly as possible, but don’t space them any further than 6 feet apart. This may cause the railing between the posts to sag. 

Use a pencil and a tape measure to mark where each post will go, drawing lines to indicate the sides of each post as well as the center (marked with a line and a “C” to avoid confusion). This is not the time to “wing it” – the more accurately you mark where each post will go, the easier it will be to place them, and the sturdier your railing will be.

Once you’ve finished planning, cut your 4×4 posts to the permitted and preferred height so that you can begin the installation process.

How to Attach Deck Railing Posts to the Inside of the Framing 

Using bolts to attach your deck railing posts to the inside of the frame creates a strong attachment. However, depending on your state’s building requirements, you may have to reinforce inside posts by installing blocking between the joists as well. This 10-minute video explains blocking along each side of the rim.


Materials Needed:

  • 4×4 deck posts
  • Pencil
  • Measuring tape 
  • Leveler
  • Clamp
  • Hammer
  • Bolts (at least 5 in. long for 4×4 deck posts, 2 bolts per post)
  • Power drill
  • Long drill bit (same length as the bolts)
  • Wrench
  • Washers
  • Nuts


Installation Instructions: 

  1. Clamp the post to the inside of the frame so that it stays in place. 
  2. Drill two holes into the outside framing where the bolts will go. For maximum stability, make sure the bolt holes are in the center of the post, 1.5 to 2 inches from the top and bottom of the frame. Keep the drill as level as possible, stopping to release the wood chips when drilling becomes difficult or if the bit begins to smoke. 
  3. Use the hammer to put the bolts through the holes you just made.
  4. On the other side, slip the washers on the ends of the bolts and tighten the nuts with a wrench. 

How to Attach Deck Railing Posts to the Outside of the Framing  

Back in the day, most deck rail posts were notched, attached to the outside of the deck frame, and driven in with screws. However, this method no longer meets most modern building code requirements. 

Instead, a bolting method similar to the one for interior posts should be used for posts attached to the outside of the frame. 


Tips for Decks with 45-Degree Corners

Installing posts on a deck with a 45-degree angle can be tricky. You can either create your own 45-degree corner post by cutting two regular 4×4 posts at a 22 ½ angle and putting them together, or install a 4×4 post so that one corner of the post is lined up with the inside corner of each angle.


Tips for Installing Deck Boards Around Posts

Placing deck boards around your posts is as simple as cutting out a big enough section to accommodate the post. Leave a slight gap between the post and the board to allow space for the deck to naturally settle or expand.

Accessories & Finishing Touches

Once your deck posts are secure, you can improve their appearance with the following accessories. 

Deck Post Caps

To prevent water from seeping into the wood posts, consider covering them with deck caps. There’s a wide variety of deck caps available in styles ranging from modern to traditional. Some even come with built-in lights to provide ambience and make your deck safer at night. You’re sure to find something to fit your style – view our railing gallery for inspiration!

Stains & Wraps

For those that prefer a modern look, a composite or PVC wrap is a popular choice. These wraps are easy to clean and scratch-resistant, and can be any color you choose. 

Those who favor a more traditional look can keep the natural wood grain by staining their deck posts. And even if you don’t want to change the wood’s original color, it’s still a good idea to seal your deck posts to prevent weather damage and slow down the rate of normal wear and tear. 

Get the Materials You Need to Build and Enhance Your Deck

There’s nothing more satisfying than completing a decking project on your own. Decks & Docks has everything you need to tackle your next DIY job, from quality lumber to marine-grade hardware. Don’t hesitate to reach out to our experts with questions – call 866-528-9663 or fill out an online contact form to talk with a member of our friendly staff!