How to Measure and Cut Stringers for Stairs: A Step-by-Step Guide

The stair stringers must be carefully measured and cut in order for stairs to be safe, comfortable, as well as code satisfactory. Even the slightest margin of error in building stairs could mean that steps become uneven or hazardous. This article will walk you through how to accurately measure and cut your stair stringers.

What Are Stair Stringers?

It is the supports on a staircase which are set diagonally. The stair stringers serve the purpose of holding the stair components together by transferring the entire load of the stairs to the floor/landing below.

Stringers are typically manufactured using:

• Pressure-treated wood
• Solid lumber
• Engineered timber (for heavy-duty applications)

Correctly sized and cut stringers ensure:

• Even step height
• Proper weight distribution
• Long-term durability

Understanding Stair Measurements: Rise and Run

Before you begin cutting, you must know these two measurements:

Rise

The vertical height from one step to the next.

Run

The horizontal depth of each step.

How to Calculate:

1. Record the overall height of the building floor to floor.
2. Divide that height by the desired riser height (usually 7–7.75 inches).
3. The result gives you the number of steps.
4. Divide the total horizontal distance by the number of steps to get tread depth.

Tip: Always make it a point to check the prevailing building regulations before locking your measurements.

Tools and Materials Needed

With proper tools, work is both precise and safe:

• Framing square
• Stair gauges
• Tape measure
• Pencil or marker
• Circular saw
• Handsaw (for finishing cuts)
• Level
• Safety gloves and goggles

Step-by-Step: How to Measure Stair Stringers

Step 1: Measure Total Stair Height

Measure from the finished lower floor to the finished upper floor.

Step 2: Determine Number of Steps

Total height is divided by standard riser height.

Step 3: Mark Rise and Run on Framing Square

Place the stair gauges on your framing square based upon the calculated values for rise and run.

Step 4: Lay Out the Stringer

Line up the square on the top edge of the board and mark the first step. 

Step-by-Step: How to Cut Stair Stringers

Step 1: Double-Check Measurements

Before cutting, verify all markings.

Step 2: Cut Along the Marked Lines

Use the circular saw to make most of the cut, stopping before turning the corner.

Step 3: Finish Corners with a Handsaw

This prevents overcutting and weakens the stringer.

Step 4: Test Fit

Position the stringer and verify that:

• Even step height
• Level treads
• Landing with secure contact

How to Install Stair Stringers Correctly

• At the top of the stringer to the header/landing
• Attach the bottom portion to the floor
• Space stringers evenly (usually 16 inches apart)
• Ensuring that all stringers are of equal strength before they undergo final installation

OSHA reports show that more than 24,882 stair-related injuries occur every year in the construction industry alone, many due to inconsistent riser heights or unstable stair bases.

Common Mistakes to Avoid

• Cutting without checking local regulations
• Cutting corners too much
• Using warped or poor quality lumber
• Uneven riser heights
• Omitting test fit prior to installation

To avoid these errors means staying safe and sound. According to OSHA’s 2019 data, slips, trips, and falls contributed to 1030 deaths of all workplace fatalities in construction. Faulty or uneven stairs are one of the main culprits.

Building Code and Safety Requirements

In most regions (including the U.S.):

• Maximum riser height: 7.75 inches
• Minimum tread depth: 10 inches
• Uniform riser height across all steps

Note: The standards to use in a country vary. Before building, refer to local building codes.

Frequently Asked Questions

How many stringers are needed for stairs?

Typically, one stringer every 16 inches of stair width.

Can stair stringers be reused?

Only if they are undamaged, level, and meet current code requirements.

What wood is best for stair stringers?

Pressure-treated lumber or top-quality structural lumber is recommended.

Final Thoughts

Measuring and cutting stair stringers is one important thing that can make a stairway robust as well as safe for use. Measuring, using proper tools, as well as certain factors related to building codes, can enable you to create a stairway as a professional carpenter does. If you are seeking quality parts or construction materials for construction related to scaffolding, AAIT Scaffold can offer you the very best options available.