how to make a 3 step stair stringer

How to Build a 3-Step Stair Stringer

By Andrew BrownDecember 4, 2025

Building a 3-step stair stringer might seem like a daunting task, but with the right tools and a step-by-step approach, it's a manageable DIY project. A stair stringer is the supporting structure of a staircase, and constructing a 3-step stringer involves creating a template, cutting the stringer, and finally, installing it. Let's dive into the process.

Before you start, ensure you have the necessary tools and materials. You'll need a tape measure, pencil, circular saw, jigsaw, drill, screws, and safety gear like goggles and gloves. For materials, you'll need 2x12 pressure-treated lumber for the stringer, 2x4 lumber for the risers, and 3/4" plywood for the treads.

Creating the Stair Stringer Template

To ensure your staircase is safe and functional, you need to create an accurate template for your stringer. This involves measuring the rise and run of your stairs, which are the vertical and horizontal distances between steps.

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For a standard staircase, the rise is typically 7 inches and the run is 10 inches. However, these measurements can vary depending on your specific needs and local building codes. Once you have your measurements, draw the stringer template on a piece of cardboard or thin plywood.

Marking the Stringer Template

Start by drawing a straight line across the top of your template. This will be the back edge of your stringer. Next, mark the rise and run measurements along this line. The rise marks will be 7 inches apart, and the run marks will be 10 inches apart. Connect these marks with a curved line to create the shape of your stringer.

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You'll need to create three of these templates, one for each step of your staircase. Make sure to label each template with its corresponding step number to ensure you cut them in the correct order.

Cutting the Stringer Template

Once you have your templates, it's time to cut your stringer. Start by laying out your 2x12 lumber on a flat surface. Place your first template on the lumber and use a pencil to trace around it. Repeat this process for the remaining two templates, making sure to space them evenly along the 2x12.

Use a circular saw to cut along the traced lines. Make sure to use a fine-tooth blade to ensure a clean cut. After cutting, you should have three stringer blanks that match your templates.

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Installing the Stair Stringer

Now that you have your stringer blanks, it's time to install them. Before you start, make sure your staircase is square and level. This will ensure that your stringer is properly aligned.

Start by attaching the bottom stringer blank to the bottom of your staircase. Use screws to secure it in place. Make sure the back edge of the stringer is flush with the back of the staircase. Repeat this process for the remaining two stringer blanks, spacing them evenly along the staircase.

Attaching the Riser and Treads

Once your stringers are in place, it's time to attach the risers and treads. The risers are the vertical pieces that separate each step, and the treads are the horizontal pieces that you walk on.

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Start by attaching the risers. Cut 2x4 lumber to the width of your staircase and screw them into place between each stringer. Make sure the top of each riser is flush with the top of the stringer.

Next, attach the treads. Cut 3/4" plywood to the width and depth of your staircase. Place each tread on top of the stringer and risers, making sure it's level and flush with the front of the riser. Screw the tread into place from the bottom, using screws that are long enough to penetrate into the stringer but not so long that they poke through the top of the tread.

Finishing Touches

With your stringer installed and your risers and treads attached, your staircase is almost complete. The final step is to finish the staircase to match the rest of your home.

This might involve painting or staining the stringer, risers, and treads, or it might involve installing a handrail or other safety features. Make sure to follow your local building codes and consult a professional if you're unsure about any aspect of the finishing process.

Building a 3-step stair stringer is a rewarding DIY project that can significantly improve the functionality and aesthetics of your home. With the right tools, materials, and a careful approach, anyone can create a safe and functional staircase. So why wait? Start planning your staircase today and enjoy the sense of accomplishment that comes with a job well done.