Pro Spring Black Friday event is on now. Don't wait!  Shop Now

Building Deck Stairs and Railing

The final step to building your new deck is to build your stairs and a railing. Consult your local building codes to get all the details and formulas you’ll need to make sure your stairs are up to code. To help you get started, a good general rule about outdoor stairs is: Twice the riser height (the vertical part of a step), plus the run of the step (the horizontal part) should equal between 24- and 27-inches. We’ll show you how to build your new stairs and add a railing to your deck.

Skill Level: Intermediate

Before starting any building project check with your municipal office for local building codes, regulations and zoning restrictions.    

  1. Step 1 Build Steps for your Deck

    Man making a wooden step

    First, we’ll show you how to build deck stairs. Your deck stairs should be at least 3-feet wide for ease of traffic flow and safe use and most codes require a 3-foot minimum anyway. Once you’ve figured out how many steps you need, you’ll need to cut stringers. Stringers are the wooden frames for the steps. Use a framing square to transfer the measurements to a piece of lumber.  After you’ve marked off all the steps, use a circular saw to cut most of the way, and then a jigsaw to finish the cut. Try not to cut past the mark in the corner because this will weaken your stairs. You can then reuse your first stringer as a template to trace out any additional ones you’ll need.

    How to Build Stairs with a Landing 

    How to Build Stair Stringers 

  2. Step 2 Assemble and Install Stairs

    People working on a deck

    You should assemble the stairs on the ground first, which will allow you to locate your posts and set the stair height accurately. Continue installing your stringers 16-inches apart for the width of your stairs. Now you’ll need to attach the stairs to the deck. First, we install a stair hanger or crossbrace, constructed from 2” x 10” boards. Temporarily attach your stairs to the deck to mark the locations for your postholes. Mark your postholes, pour the concrete, place your posts and level them and then attach them to the stairs.    

  3. Step 3 Attach Tread

    Man attaching step to structure

    For the treads, if you’re trying to keep the look consistent with the rest of your deck, use the same decking boards as you used on your deck. Attach the treads with deck screws and then notch the bottom tread around the post for a nice finished look.    

  4. Step 4 Attach Railing Posts

    Man attaching railing post to deck

    Most building codes require railings for decks over 24-inches in height and most codes require these railings to be at least 42-inches high. Start by dividing the spacing of the posts to create equal distances for each rail section. The posts may be positioned anywhere between the joists. Box in the post to the framing using the rim joist as the front support and blocking to support the back and sides if required. The blocking should be the same dimensions as the joists. Next, mark the location of each post, drill a pilot hole and then cut out the post location with a jigsaw.

    How to Install Railings on a Deck 

  5. Step 5 Install Rails

    Person attaching railing to post

    Now we’ll show you how to build a deck railing. Rails are installed so that we will have something to attach the balusters or pickets to. We are using 2” x 4” boards for our top and bottom rails. Install the plastic mounts that came with your railing kit and attach the bottom rail. Once the rails are screwed to the posts, attach the balusters. By code, balusters have to be close enough together so that a 4-inch sphere can’t pass between them. After the top and bottom rails are in place, use a circular saw to cut the top off the post. This makes it flush with the rail. Repeat the process for the rest of the deck rails.    

  6. Step 6 Install Cap Rail

    Wooden railing

    To finish the railing, all that’s left to do is to install the top piece, called the cap rail. Lay the cap rail over the balusters and posts and attach it with decking screws. Continue this around the perimeter of the deck, mitering the joints where cap railings meet.    

  7. Step 7 Add Finishing Touches

    Man installing wood under deck

    As a nice finishing touch, make angle cuts on the corners of the cap rails. Your deck is almost done, but there are still a few finishing touches that you can do to make it even sturdier and last longer. Adding structural post-to-beam supports to every post and bolting the cradles to the posts with lag bolts will make your deck structure even more sturdy. Apply sealer to the cut ends of all boards to help protect it from weather and insects. You now have a completed deck.    

  8. Step 8 Protect and Maintain Your Deck

    Wooden deck

    Periodic application of a high-quality, clear water repellent or semi-transparent stain with water repellent helps to minimize warping, splitting, and other weathering problems. You may need to wait a certain period of time after you build your deck to apply the sealer or stain if you used pressure-treated wood, as it is usually wet when new. Consult your wood manufacturer’s recommendations on any waiting times. Remember, it’s important to regularly maintain any deck, no matter what it’s made of.    

What You Need for This Project

Related Resources