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How to build the Perfect Deck Stairs


Adding stairs to an existing deck or porch is a quick and easy job, if you have the right tools and know-how, and can be completed in just a few simple steps. Make sure you always double-check building codes and requirements in your local area before you begin.

Typically, deck stairs are made from several stringers, spaced about a foot apart. You may need two or three depending on the width of your staircase. These are attached to the deck with hangers and generally rest on a concrete pad. As you’re thinking about your steps, imagine how they will fit into your landscape and where they are best set levelly on the ground. You can build your own custom stringers, or buy them pre-cut at your local big-box hardware store.

Step one: Measure how high you’ll need your steps to be. To find the total vertical height of your stairs, lay your long level on the top of the deck. Extend it slightly from the edge and measure down to the landing location. You will use this number to determine how many steps you’ll have and how high each will be. (Let’s say the total rise is 142.24cm). The next job is to find the rise of each step. Divide 142.24 by 17.78 cm. (the ideal height of a normal step) to get 8. You will have 8 steps at 17.78 cm high a piece. (Only 7 steps if you use the deck itself as the top step).

Step two: Install a concrete pad. Follow the concrete manufacturer’s instructions to mix and prepare concrete. Form a simple frame to pour concrete in. Make sure it is wider than the width of your steps.

Step three: Cut the Stringers. Once you’ve decided how many steps you’ll need and the height of each you can use 5.08cm x 30.48cm to create your stringers. You can use a right angled framing square to draw the outline on your board before you cut. Slide the square along the plank, and mark both rise and run for each step. Continue marking until you have the correct number of steps laid out. Cut the stringer with a circular saw. You can then lay your completed stringer on your second (and third) 5.08cm x 30.48cm and trace it as a template to cut the second one.

Step four: Attach the Stringer: Simply cut a board the width of your step to support your stringer. A 5.08cm x 20.32cm works well for this. Attach it the deck using joist hangers or long decking screws. Then attach a hanger to your stringer and place it against the support board. Use a level to make sure you are aligning it plumb with the existing deck and mark it with a pencil. Secure the hanger to the deck using wood screws. Lastly, secure the hanger to the inside of the stringer with nails or screws. You can also decide to install concrete anchors to the bottom to secure your steps to the concrete pad.

Step five: Cut the treads (the part you actually step on) to the correct length and fasten them to the stringers with decking screws. If your local code requires a handrail, the posts used to support the stair rail are typically bolted to the stringers before installing the steps. Our premium composite decking is a great choice of material for the treads on your deck. Their low maintenance and durable surface is perfect for heavy traffic areas like stairs.

That’s it! You’re finished. You can add toe kicks, rails and finish work as your tastes and local codes dictate.

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