How to Install Stairs on a Deck

How to Install Stairs on a Deck

May 22, 2024

Installing deck stairs is an important part of a functional and safe deck. Stairs and stair rails provide easy access to your deck and ensure the safety of those using it.

Your stairs must be built with precision and care to ensure they are durable and meet safety standards. This guide will walk you through the process, from planning and preparation to the final touches, ensuring you have all the necessary information to build robust and attractive deck stairs.

Planning and Preparation

Design and Layout:

  • Begin by sketching the layout of your stairs, considering the rise (vertical height) and run (horizontal length) of each step. Accurate measurements ensure the stairs are comfortable and comply with building codes.
  • Use online deck stair calculators to help determine the exact measurements and layout. These tools can simplify the process and reduce the risk of errors.

Safety and Permits:

  • Before building, check your local building codes and obtain any necessary permits. Building codes can vary by location, so ensuring your stairs meet all legal requirements is essential.
  • Safety should always be a priority. To protect yourself during the construction process, wear appropriate safety gear, including gloves, eye protection, and sturdy footwear.

Tools and Materials:

  • Gather all the necessary tools and materials before you begin. This includes:
    • Tools: a saw, level, tape measure, drill, clamps, framing square, and circular saw.
    • Materials: Pressure-treated lumber for stringers, treads, and risers, galvanized fasteners, and concrete for footings.
  • Ensure that all materials are suitable for outdoor use and can withstand exposure to the elements. Using pressure-treated lumber and galvanized fasteners will help prevent rot and corrosion, extending the lifespan of your stairs.

Preparation Steps:

  • Start by measuring the total height from the deck surface to the ground (total rise). This measurement will help you determine the number of steps (risers) needed.
  • Calculate the number of risers by dividing the total rise by the desired height of each riser. The maximum allowable height for each riser is typically 7 ¾ inches, but it is best to check your local codes for specific requirements.
  • Plan the placement of your stairs to ensure they do not obstruct the natural flow of foot traffic and provide a convenient exit route in an emergency. When deciding where to position the stairs, consider the overall layout of your deck and the surrounding landscape.

Measuring and Cutting Stringers

Total Rise and Run Calculation:

  1. Measure the Total Rise:
    • Start by measuring the total height from the top of the deck surface to the ground, referred to as the total rise. Extend a straight board from the deck over the proposed landing spot and measure straight down to the ground.
    • This measurement will help determine the number of steps and the height of each riser.
  2. Calculate the Number of Risers:
    • Divide the total rise by the maximum riser height allowed by local building codes, typically 7 ¾ inches. This calculation gives you the approximate number of risers needed.
    • Adjust the riser height if necessary to ensure the steps are evenly spaced. For example, if the total rise is 45 inches, you would divide 45 by 7.75, which equals approximately 5.8. Round this number to the nearest whole number, resulting in 6 risers.
  3. Determine Tread Depth and Run:
    • The tread depth (the horizontal part of each step) is typically around 10-11 inches. The run is the horizontal distance covered by each step, usually including a slight overhang or nosing for safety and aesthetic purposes.

Marking and Cutting Stringers:

  1. Mark the Stringers:
    • Use a framing square to mark the stair pattern on 2x12 pressure-treated lumber. Position the square so that one side aligns with the desired riser height and the other with the tread depth.
    • Mark the positions of each step on the stringer, ensuring consistency in the rise and run. This step is crucial for maintaining the stairs' uniformity and stability.
  1. Cut the Stringers:
    • Carefully cut along the marked lines using a circular saw, and be careful not to cut beyond the lines to avoid weakening the stringers. Finish the cuts with a handsaw to ensure precision and prevent overcutting.
    • Once the first stringer is cut, use it as a template to mark and cut the remaining stringers. This ensures all stringers are identical, contributing to the overall stability and appearance of the stairs.
  1. Test Fit the Stringers:
    • Before cutting all the stringers, test fit the first one to ensure it fits appropriately against the deck and provides a level surface for the treads. Make any necessary adjustments to the measurements and cuts before proceeding with the remaining stringers.

Installing the Stringers

Foundation Preparation:

  1. Excavate the Base:
    • Dig out the area where the base of the stairs will rest, ensuring proper drainage and a stable foundation. The depth and width of the excavation should accommodate the concrete footings needed to support the stringers.
    • The base should be level and compacted to prevent shifting or settling over time.
  1. Create Concrete Footings:
    • Pour concrete footings for the stringers, following local building codes for depth and reinforcement. The footings should extend below the frost line to prevent movement due to freeze-thaw cycles.
    • Allow the concrete to cure completely before proceeding with the installation of the stringers. If you don’t want to use concrete footings, there are numerous instant footing options available.

Attaching Stringers:

  1. Secure the Stringers to the Deck Frame:
    • Attach the top of the stringers to the deck frame using L-brackets or joist hangers, ensuring they are level and properly aligned. Secure the bottom of the stringers to the concrete footings using galvanized connectors and appropriate fasteners.
    • Ensure the stringers are spaced evenly and aligned correctly to ensure the stairs are stable and safe.
  2. Ensure Level and Plumb Alignment:
    • Use a level to check the alignment of the stringers, adjusting as necessary to ensure they are plumb (vertically straight) and level.
    • Double-check all measurements and connections before proceeding to the next step to ensure accuracy and safety.

Attaching Risers and Treads


  1. Cut and Attach the Risers:
    • Cut the risers to the desired height, ensuring they are all the same size to maintain uniformity. The risers should fit snugly between the stringers.
    • Attach the risers to the stringers using galvanized nails or screws. Begin at the bottom and work your way up, maintaining consistent spacing to ensure each step is level and even.
  2. Ensure Compliance with Code:
    • Ensure that the risers meet local building code requirements, which typically specify the maximum and minimum riser heights.
    • Use a level to check each riser as you install it, ensuring it is perfectly vertical and aligned with the stringers.


  1. Cut the Treads:
    • Measure and cut the treads to the correct length, allowing a slight overhang (nosing) for better footing and drainage. The typical tread depth is 10-11 inches, including the overhang.
    • Use a circular saw to cut the treads and pre-drill holes to prevent splitting when attaching them to the stringers.
  2. Attach the Treads:
    • Start by attaching the bottom tread, working your way up. Use galvanized fasteners to secure the treads to the stringers, ensuring they are level and evenly spaced.
    • Leave a small gap between the treads (around ¼ inch) to expand and contract the wood and prevent debris buildup. This gap also facilitates water drainage, reducing the risk of rot.
  3. Check Alignment and Level:
    • After attaching all the treads, use a level to check that they are even and properly aligned. Adjust to ensure a smooth, safe walking surface.

Adding Railings and Finishing Touches

Installing Railings:

  1. Attach Railing Posts:
    • Securely attach railing posts to the deck and stringers using galvanized screws or bolts. The posts should be positioned at the top and bottom of the stairs and intervals specified by local building codes.
    • Ensure the posts are plumb and level, providing a sturdy foundation for the rest of the railing system.
  2. Install Balusters:
    • Attach balusters to the railing posts, ensuring they are evenly spaced and comply with code requirements. The gap between balusters should not exceed 4 inches to prevent accidents.
    • Use a level to check each baluster as you install it, ensuring it is vertical and evenly spaced.
  3. Add the Top Rail:
    • Secure the top rail to the railing posts and balusters, ensuring it is level and firmly attached. The top rail should provide a comfortable and sturdy handhold.


  1. Sand and Smooth:
    • Sand any rough edges or splinters on the risers, treads, and railings to prevent injuries.
    • Pay special attention to the edges and corners, which can become sharp during cutting.
  2. Apply Weatherproof Finish:
    • Apply a weatherproof finish or stain to protect the wood from the elements. Choose a high-quality exterior finish that protects against UV rays, moisture, and temperature changes.
    • Ensure all surfaces, including the treads, risers, and railings, are thoroughly coated. Allow the finish to dry completely before using the stairs.
  3. Final Inspection:
    • Conduct a thorough inspection of the stairs to ensure all components are securely attached and properly aligned. Check for loose fasteners or uneven surfaces, and make necessary adjustments.
    • Test the stability of the stairs by applying weight to different areas, ensuring there is no movement or instability.
    • Add any special touches, such as post caps or lights.

Safety Tips and Maintenance

Safety Tips:

  1. Double-Check Measurements:
    • Always double-check your measurements and cuts before proceeding to the next step.
    • Measure twice cut once. This age-old adage is essential when building stairs to avoid costly mistakes and ensure uniformity.
  2. Seek Professional Advice:
    • If you are unsure about any step or encounter unexpected issues, seek professional advice. Consulting a professional can prevent mistakes that could compromise the safety and durability of your stairs.
    • Some aspects of stair construction, such as meeting specific local building codes, may require professional expertise.
  3. Use Safety Gear:
    • Always wear appropriate safety gear, including gloves, eye protection, and sturdy footwear. Safety gear can protect you from common construction injuries, such as cuts, splinters, and debris.
    • Ensure your work area is clean and free of hazards to prevent accidents.


  1. Regular Inspections:
    • Regularly inspect your deck stairs to identify any signs of wear and tear, such as loose fasteners, rotting wood, or unstable components. Regular maintenance can extend the lifespan of your stairs and ensure they remain safe to use.
    • Check for any structural issues, such as shifting or settling, which can compromise the stability of the stairs.
  2. Cleaning and Sealing:
    • Clean your stairs periodically to remove dirt, leaves, and other debris that can cause rot and decay. Use a mild detergent and a brush to clean the treads and risers.
    • Reapply a weatherproof sealant or stain every few years to protect the wood from moisture, UV rays, and temperature changes. This helps prevent cracking, warping, and splintering.
  3. Repair and Replace:
    • To maintain the integrity and safety of your stairs, promptly repair any damaged components, such as cracked treads or loose railings. Use appropriate materials and techniques to ensure the repairs are durable and secure.
    • Replace any severely damaged or rotten wood to prevent further deterioration and potential accidents.