Stair Treads and Risers: Getting the Steps Right

Now that you understand the overall dimensions of your staircase, let’s zoom in on the individual steps themselves. Building codes have specific rules about stair treads and risers to ensure they’re comfortable and safe to use. We’ll also explore some special considerations for winder treads, nosings, and even exterior stair treads.

Risers: Setting the Right Height

Risers are the vertical parts of a step, and their height plays a crucial role in how comfortable your staircase feels. Too high, and climbing the stairs becomes tiring. Too low, and you’ll feel like you’re taking baby steps. Here’s what the codes say:

Riser Height:

  • Maximum Height: Risers should be no more than 7 ¾ inches high. This helps ensure a comfortable stride and reduces the risk of tripping.
  • Uniformity: While some variation is allowed, the difference between the tallest and shortest riser in a single flight of stairs cannot exceed ⅜ inch. This helps maintain a consistent rhythm as you climb.
  • Slope: Risers can be vertical or slightly sloped, but the angle of the slope cannot exceed 30 degrees from vertical. This prevents the steps from becoming too shallow and uncomfortable.
  • Open Risers: If you opt for a staircase with open risers (no vertical part between the treads), any openings more than 30 inches above the floor or ground below must be small enough to prevent a 4-inch diameter sphere from passing through. This is a safety measure to prevent small children or objects from falling through.

Treads: Finding Your Footing

Treads are the horizontal parts of a step – the part you actually step on. Their depth is crucial for providing secure footing and preventing accidental slips.

Tread Depth:

  • Minimum Depth: Treads should be at least 10 inches deep, measured from the front of one tread to the front of the next. This provides enough space for your foot to land comfortably.
  • Uniformity: Similar to risers, the difference between the deepest and shallowest tread in a single flight of stairs cannot exceed ¾ inch. This helps maintain a consistent stride.

Winder Treads: Navigating Turns Safely

Winder treads are special treads used to create turns in a staircase. They’re wider at one end than the other, creating a pie-shaped step.

Winder Tread Depth:

  • Minimum Depth at Walkline: Winder treads should have a depth of at least 10 inches at the walkline (the imaginary line representing the typical path someone takes when walking on the stairs).
  • Minimum Depth at Any Point: Even at their narrowest point, winder treads should have a depth of at least 6 inches.
  • Uniformity: The difference between the deepest and shallowest winder tread in a single flight of stairs cannot exceed ⅜ inch.

Nosings: The Finishing Touch

The nosing is the edge of the tread that projects slightly over the riser below. It provides a visual cue and a bit of extra space on the tread.

Nosing Requirements:

  • Rounded or Beveled: The nosing should have a rounded edge with a maximum radius of 9/16 inch, or a beveled edge with a maximum bevel of ½ inch. This helps prevent tripping.
  • Projection: The nosing should project out from the tread by at least ½ inch but no more than 1 ½ inches.
  • Uniformity: The difference between the largest and smallest nosing projection in a staircase cannot exceed ⅜ inch.

Exterior Stair Treads: Weathering the Elements

If you’re building or renovating an exterior staircase, you’ll need to choose materials that can withstand the elements. Plastic composite stair treads are a popular option, but they must still comply with building codes.

Key Considerations:

  • Slip Resistance: Exterior stair treads should have a textured surface to provide adequate grip, even when wet.
  • Durability: Choose materials that can withstand freeze-thaw cycles and resist fading and cracking from sun exposure.

Landings: Creating Resting Points

Landings are flat platforms within a staircase that provide a place to rest or change direction.

Landing Requirements:

  • Top and Bottom Landings: Every staircase must have a landing at the top and bottom.
  • Landing Width: The width of a landing should be at least as wide as the staircase it serves.
  • Landing Depth: For straight staircases, the depth of the landing in the direction of travel should be at least 36 inches.

Stairway Walking Surface: Ensuring a Smooth Path

The walking surface of your staircase, including the treads and landings, should be relatively level to prevent tripping.

Slope:

  • Maximum Slope: The walking surface should not slope more than 2 percent (approximately ¼ inch per foot). This ensures a comfortable and safe walking experience.

By following these guidelines, you can create a staircase that is not only code-compliant but also a pleasure to use for years to come.