How to Build Stair Stringers - 2023 Updated Guide!

Are you a first-time homeowner or a busy parent looking to enhance your living space with a new staircase?

Or perhaps you’re an enthusiastic DIYer eager to take on a new challenge in home improvement?

At some point, many of us find ourselves facing the dilemma of wanting to replace a worn-out staircase or add a functional set of stairs to our living spaces.

But here’s the good news: You don’t need to be a construction expert or a seasoned DIY pro to master this skill.

My 2023 updated guide on “How to Build Stair Stringers” is designed to walk you through the entire process, step by step.

So, say goodbye to puzzling over measurements and get started on your journey to becoming a stair stringer expert!

How to Build Stair Stringers?

Building stair stringers requires careful measurements, accurate cutting, and proper construction techniques. Here’s my step-by-step guide to help you through the process:

Steps	Estimated Time (for one person)
Step 1: Calculating Your Measurements	30-45 minutes
Step 2: Prepare the Stringer Board	60-75 minutes
Step 3: Mark the Stringer Notches	45-60 minutes
Step 4: Cut the Notches	60-75 minutes
Step 5: Test the Stringer	30-45 minutes
Step 6: Attach Stringers	45-60 minutes
Step 7: Install Treads and Risers	60-75 minutes
Step 8: Finish and Safety	60-75 minutes

Step 1: Calculating Your Measurements

Use a tape measure to determine the vertical distance between the top of the finished floor below and the finished floor at the top where the stairs will connect.

If the floor is unfinished, take this into account in your measurements.

This measurement is known as the total rise of the staircase.

Decide on the desired height for each individual step, known as the riser height.

Typically, risers are around 7 inches tall.

Divide the total rise by the chosen riser height to determine the total number of stairs needed.

For instance, if the total rise is 56 inches and you’ve decided on a riser height of 7 inches, the calculation would be 56 / 7 = 8 stairs.

This value represents the number of risers your staircase will have.

To calculate the depth of each step, known as the tread depth, consider a common value of around 10 inches.

This depth provides comfortable foot placement while ascending the stairs.

However, adjust this measurement as needed for specific preferences.

Use the Pythagorean theorem (a² + b² = c²) to calculate the length of the stringer.

For example, if the total rise is 60 inches (a) and the run (horizontal distance) is 84 inches (b), the calculation would be:

a² + b² = c²

60² + 84² = c²
3600 + 7056 = c²
10656 = c²

c ≈ √10656
c ≈ 103.2 inches

This calculated value (c) represents the length of the stringer needed.

Required Tools

Tape measure

Step 2: Prepare the Stringer Board

Choose high-quality and suitable lumber for your stringer board.

The commonly used size is 2×12 boards.

Opt for pressure-treated lumber, especially for outdoor use, as it offers enhanced durability against moisture and pests.

Measure and calculate the total run of your staircase.

The total run determines the stringer length and sets the foundation for the entire stair structure.

Use a saw (circular saw or miter saw) to cut the selected lumber to the determined length.

Ensure the cut is clean and accurate, as this will influence the overall safety of your staircase.

Position the cut stringer board on a flat surface with the wide face (the side with the greater width) facing up.

This orientation is crucial for accurate marking.

Retrieve your framing square, a versatile tool with a right-angle triangular body and various measurements marked on its edges.

Identify the rise measurement you calculated earlier.

On the wide face of the stringer board, place the framing square’s long side against the board’s edge, forming a right angle.

Align the square’s rise measurement with the edge and mark the point on the board.

With the framing square still in place, align the square’s tread measurement with the previously marked rise point.

Mark this point on the board as well.

Designate one stringer as the reference by using the marked rise and tread points.

This reference stringer will serve as a template for marking the remaining stringers to ensure uniformity.

Position the framing square on the edge of the stringer board, aligning the previously marked rise and tread points with the square’s measurements.

Mark these points on the edge.

Use the reference stringer as a guide to mark the rise and tread measurements on other stringers.

Place the framing square against each stringer’s edge and mark the corresponding points for consistent and precise markings.

Required Tools

Circular saw or miter saw
2×12 lumber

Safety goggles
Ear protection

Step 3: Mark the Stringer Notches

Refer to the rise and tread marks you made on the stringer board in the previous step.

These marks will serve as the foundation for marking the notches.

Place a carpenter’s square against the edge of the stringer board, aligning it with the rise and tread marks.

The square’s right angle should be flush with the board’s edge.

Using the carpenter’s square as a guide, draw perpendicular lines across the width of the stringer board at each rise and tread mark.

These lines will indicate the precise locations where the treads and risers will be positioned.

Calculate the depth of each notch to ensure a snug and secure fit for the treads.

This depth is determined by subtracting the thickness of one tread from the tread depth you calculated earlier.

This step is vital for achieving a seamless and comfortable staircase.

Mark the rise and run measurements corresponding to the specific step along each perpendicular line.

The rise measurement indicates the height of each riser, while the run measurement signifies the horizontal distance of each tread.

Repeat this process for each step, marking the rise and run measurements on the perpendicular lines.

This will create a series of marks that outline the shape of the stairs along the stringer board.

As you complete marking the rise and run measurements on each notch line, you’ll start to see the outline of the stairs taking shape on the stringer board.

These marks will guide the precise cutting of the notches in the subsequent steps.

Required Tools

Carpenter’s square
Pencil or marking tool
Measuring tape

Step 4: Cut the Notches

Prioritize safety by wearing protective gear, including safety goggles to shield your eyes and ear protection to reduce noise exposure.

Set up your work area with ample space and proper lighting.

Securely clamp the stringer board to prevent movement during the cutting process.

Using a circular saw, cut along the lines you marked on the stringer board for the notches.

Start the saw before it makes contact with the wood, and maintain a steady hand as you guide the tool along the marked lines.

Make multiple cuts close together along the marked lines to ensure accuracy and prevent splintering.

This technique, known as “kerf cuts,” makes it easier to remove the waste wood.

Once the multiple cuts are made, you’ll have a series of closely spaced cuts outlining the notch.

To remove the waste wood between the cuts, carefully use a chisel.

Gently tap the chisel with a hammer to break away the wood along the marked lines.

Be patient as you chisel out the waste wood, ensuring that the notches are clean, even, and accurately shaped.

After cutting and chiseling, check the fit of the treads and risers in the notches.

Make any necessary adjustments before proceeding.

Repeat the cutting and chiseling process for each marked notch on the stringer board.

Consistency and accuracy in each cut are vital for the overall stability of the staircase.

Required Tools

Circular saw or miter saw
Chisel
Hammer

Safety goggles
Ear protection
Clamps

Step 5: Test the Stringer

Carefully place the stringer in its intended position, aligning it with the lower landing or floor and the upper landing or floor.

Ensure that the stringer is oriented correctly, with the notches facing upwards.

Verify that the notches you’ve cut into the stringer securely and snugly accommodate the treads and risers.

Each tread and riser should fit comfortably into their respective notches.

Place the stringer on a level surface, ensuring it is steady and well-balanced.

This surface can be the lower landing, a flat piece of lumber, or a set of supports designed for this purpose.

Position a level across the treads of the stringer.

The level should be placed perpendicular to the stringer’s length and centered on a tread.

This will help you assess whether the treads are horizontal and level.

Observe the bubble in the level’s vial.

The stringer’s treads are level if the bubble is centered between the two lines on the vial.

If the bubble is off-center, adjust the stringer’s position until the bubble is perfectly centered.

Carefully adjust the stringer’s position if the bubble isn’t centered and the treads aren’t level.

You may need to elevate one end slightly or make other minor adjustments until the bubble is centered.

After adjusting the stringer’s position, re-check that the notches still securely accommodate the treads and risers.

The adjustments you make to achieve levelness should maintain the fit of the stairs.

Step back and visually assess the overall fit of the stringer in its intended position.

Confirm that it aligns well with upper and lower landings or floors and that the treads are level and secure.

Required Tools

Level
Flat surface or supports

Step 6: Attach Stringers

Choose appropriate brackets or hangers designed for attaching stringers to a wall.

These brackets provide a strong connection between the stringers and the wall, ensuring stability.

Carefully position the stringers against the wall in the intended location.

Ensure the notches align with the treads and risers and the stringers are level and plumb.

Following the manufacturer’s instructions, attach the selected brackets or hangers to the stringers.

Secure them firmly to the wall structure using appropriate screws or fasteners.

Place the stringers in their intended positions for freestanding stairs, ensuring they are aligned with the lower and upper landings.

Confirm that the stringers are level and plumb.

Identify suitable attachment points on the floor or supporting structure.

These can include joists, beams, or specially designed anchors.

Depending on the attachment points, use nails, screws, or anchors to secure the stringers to the floor or supporting structure.

Make sure the attachment is strong and secure to prevent wobbling or instability.

As you attach the stringers, regularly check for levelness and plumpness.

Adjust as needed to ensure the staircase is properly aligned.

Place a level against the stringers to verify they are still level and plumb after the attachment.

This final check is crucial to the staircase’s overall stability.

Required Tools

Brackets or hangers (for wall attachment)
Nails, screws, or anchors

Level
Drill (if using anchors)

Step 7: Install Treads and Risers

Ensure the stringers are securely attached and positioned correctly, with the notches accommodating the treads and risers as intended.

Begin by attaching the risers, the vertical components enclosing the space between each step.

Align the top edge of each riser with the corresponding notch on the stringers.

Secure the risers in place using nails or screws.

Ensure the attachment is firm and the risers are flush with the notches and stringers.

Once the risers are in place, install the treads, which are the horizontal surfaces that users step on.

Position each tread on top of the corresponding riser and notch.

Attach the treads securely to the stringers using nails or screws.

Place the fasteners near the edges of the treads, ensuring they are driven straight and countersunk to prevent tripping hazards.

As you install each tread and riser, use a level to verify that the treads are horizontal and the risers are vertical.

If you’re working with an open stringer design, where the notches are visible from the side, consider attaching the treads from underneath.

This method maintains the clean appearance of the stringers.

Maintain consistent spacing between treads and risers to ensure users’ uniform appearance and comfortable stepping experience.

After installing all treads and risers, go back and double-check the attachments to ensure they are secure and even.

Required Tools

Nails or screws
Level

Step 8: Finish and Safety

Use sandpaper to smooth any rough spots or sharp edges on the treads and risers to enhance safety and comfort.

This step prevents splinters and creates a more pleasant walking experience.

Customize the appearance of your staircase by choosing a finishing option that suits your preference and the surrounding decor.

Common choices include paint, stain, or a protective clear finish.

If you opt for paint or stain, carefully apply it to the treads and risers.

Ensure there is even coverage, and give each coat enough time to dry.

Consider applying a protective finish to the treads and risers to enhance durability and longevity.

Clear polyurethane or varnish can provide a protective layer that resists wear and tear.

If your local building codes require a handrail, ensure compliance by installing one.

Attach the handrail securely to the wall or posts adjacent to the staircase.

Ensure the handrail is installed at the proper height according to local codes.

This height is typically around 34 to 38 inches above the treads, offering a comfortable grip for users.

Whether attaching the handrail to the wall or posts, use strong brackets or supports to ensure a secure attachment.

Test the handrail for stability and adjust if necessary.

Periodically inspect the staircase for signs of wear or damage.

Perform any necessary touch-ups or repairs to maintain its safety and appearance.

Required Tools

Sandpaper
Paint, stain, or clear finish
Paintbrush or stain applicator
Handrail (if required by local codes)
Brackets or supports for handrail attachment
Drill (for handrail attachment)

Bottom Line

Building stair stringers might seem daunting at first, but with the right knowledge and guidance, it’s a project that’s well within your reach.

By following the detailed steps outlined in this guide, you’ve gained insights into accurate measurements, precise cuts, secure attachments, and finishing touches that ensure both safety and aesthetics.

As you embark on your stair stringer journey, don’t hesitate to refer to this guide whenever you need a refresher or guidance.

Happy DIYng!

FAQ

Do I need 2×10 or 2×12 for stair stringers?

When building stair stringers, it’s recommended to use 2×12 lumber for their construction.

Notching smaller stock like 2x10s doesn’t provide enough wood to handle the loads and stresses associated with a staircase safely.

Opting for 2x12s ensures that the stringers are sturdy and capable of supporting the weight and traffic of people using the stairs.

What is the minimum depth for stair stringers?

The minimum required tread depth for stair stringers is 10 inches (254 mm).

This measurement is taken horizontally between the vertical planes of the foremost projection of the adjacent treads at a right angle to the leading edge of the tread.

This ensures that each step provides enough space for comfortable foot placement while ascending or descending the stairs.

What is the 18 rule for a staircase?

The “18 Rule” for a staircase refers to a design principle where the sum of the rise and run of each step should ideally equal 18 inches.

In the context of this rule, “rise” refers to the vertical height of the step, and “run” refers to the horizontal depth of the step (also known as the tread).

The rule suggests that each step’s total rise and run should be around 18 inches for a comfortable and ergonomic stride.

The rationale behind this rule is that a stride of approximately 18 inches is commonly considered comfortable for most individuals when walking up or down stairs.