How to Build Deck Stairs

How to Build Deck Stairs and Steps - DIY - Step by Step

As the winter cold begins to thaw away, now is the perfect time to plan out deck makeovers and renovations to create the ideal outdoor living space your home deserves! From replacing old pressure-treated decking with new composite deck boards from brands like Trex and TimberTech, swapping out worn-down wooden deck railing with a strong, modern metal or composite railing system, or adding contemporary solar deck lighting to your deck posts and rails, choosing an area of the deck or porch to start with can be a tough choice.

However, professional builders and deck inspectors recommend checking out one area first and foremost for the overall safety and longevity of your space: deck stairs and outdoor staircases. Checking and maintaining your deck stairs and steps each year can prevent any injuries and protect family, friends, and guests.

While working on, replacing or building your deck stairs looks intimidating at first, it can be a smooth construction process that really takes your outdoor space to the next level. Learn how to build deck stairs with our simple step by step guide.

How to Measure and Calculate Stair Stringers

If you're not using pre-made stair stringers from a lumberyard or big box store, you can start from scratch and build your own custom set at home! We've put together a step-by-step guide to finding the rise and run of your outdoor staircase, along with the angle and stair count: learn more in our Decks 101: How to Calculate Stair Stringers guide here!

How to Make and Cut Stair Stringer Boards

With your stair count and step measurements at the ready and a framing square in hand, now's the time to trace and cut your stair stringers out of a 2x12 pressure-treated board. Read through the Decks 101: How to Cut Stair Stringer Boards guide to find the easiest ways for even the most DIY-level builder to create the ideal stringer boards for their deck stairs.

How to Attach Stair Stringers - Step by Step

1) Attach Stair Stringers To Deck Frame

Line up your stair stringer boards in position for your outdoor staircase and attach the first stringer to the bottom of the deck frame with a structural connector or L-shaped bracket like the Simpson Strong-Tie 90 Degree Angle Bracket.

• Use a power drill and wood-to-wood structural screws such as the SDWS Exterior Wood Structural Screw by Simpson Strong-Tie or the Starborn H23 Structural Wood Screw. Choose a minimum screw length of 3 inches.
• Place the top of the stair stringer board up against the bottom of the deck frame and screw an L-bracket on each side of the stringer to securely attach it to the deck substructure.
• For the stair stringers in the middle of the staircase, measure out the width of your stairs and divide it into equal-sized sections. (If you're using three stringer boards, divide the width into two equal sections. If you're using four stringer boards, divide it into three sections, and so on). Mark out where each stringer will go, then attach the stringers along the marks the same way as you did with the first stringer.
• Lastly, fasten the final stair stringer board on the opposite side with the same process.

2) Attach Your Riser Boards

Measure and mark your riser boards to your staircase specifications. Use a circular saw or miter saw to trim the riser boards to length. We carry a wide selection of stair riser boards that match the exact colors and textures of popular composite deck boards. Or, you can use composite deck boards themselves. Either option gives your stairs a clean, finished look.

• Attach your riser boards to your stair stringers with the wood deck screw fastener of your preference. We recommend using a screw between 2 to 3 inches in length. One good option: GRK RSS screws.

3) Attach Your Stair Treads

Measure and mark your stair tread boards to your staircase specifications. Use a circular saw or miter saw to trim the tread boards to the length needed. DecksDirect recommends using square-edged or non-grooved composite deck boards for your stair treads. You can keep measurements easy by cutting your stair stringers with 10-inch stair runs, then using two 5-½ inch composite deck boards for each stair tread. That will leave one inch of nosing on the front of each stair to create a polished look for each piece of your deck staircase.

• Attach your tread planks to the top of the steps with the wood deck screw fastener of your preference. We recommend using a screw between 2 to 3 inches in length. One good option: GRK RSS screws.

4) Finish With Railing and Lighting

Mount the deck railing system that fits your home's style! Choose from metal deck railing kits, cable railing systems, and more to find the perfect fit for your outdoor style.

• Adding stair and step lighting to your newly built outdoor stairs can help add decorative touch of detail while also keeping family, friends, and guests safe as they walk up and down your hand-built stairway!