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Indoor Staircase Terminology and Standards

Whether installing stairs and railings by yourself or hiring professionals, a good knowledge of stair parts terminology helps when choosing the right design and materials.

Types of Staircases

There are two broad categories of stairs: open and closed.

A closed staircase is one with treads and risers, while an open one only has treads. Some experts also define an open stair as having one side enclosed by a wall, whereas walls or rails enclose both sides of a closed stair. Both types of staircases can have straight run and platform designs. A straight run stair goes continuously from one floor to the next and has no turns or landings. Platform stairs have landings that serve as bridges between sections where they change direction.

An L-shaped staircase has one turn and one platform, and U-shaped stairs have two turns and one platform. A double-L stair has two turns and two platforms. While these examples have straight sections, there are also curved staircases. The most prominent of these is the spiral staircase that coils on itself as it rises.

Stair Terminology and Features

  1. Riser: This is the vertical section between two steps in a staircase. Rise height varies from 5" to 8", with most between 7" and 7.5".
  2. Tread: This is the horizontal section of each step in a staircase. Also called a run, users step on this part. In simple terms, a staircase is a series of treads and risers. The width of each tread and the height of each riser are the key stair dimensions that determine the number of steps in a staircase.
  3. Nosing: In many types of staircases, the tread overlaps the end of the riser. This overlap or protrusion is the nosing.
  4. Tread: With the “run” of a staircase, we are referring to the depth of the step, or tread, minus the nosing. The tread varies between 8 ¼" and 14". The treads of most staircases vary between 9 ¾" and 10 ½".

    The tread can be calculated by dividing the total length of the staircase by the number of steps. Another method consists of calculating the space between two risers.
  1. Headroom: This is the vertical space between any step of a stair and the ceiling or other enclosed surface above it. Allowable headroom varies depending on local building codes. Typically, the main stair should have a headroom of 6’ 8".
  2. Stringer: This board is on either side of a stair and it serves as support for the risers and treads. Open stairs have cut stringers. Closed stringers look like continuous support beams. The length and width of stringers are also important stair dimensions.
  3. Railings: Also called handrails, these are long, angled pieces of wood or metal that run the length of a stair. They are useful for holding to support users while climbing up and down.
  4. Spandrel: This is stair terminology for the triangular enclosure beneath a flight of stairs. Homeowners can use this space as storage closets.
  1. Hand rail: The handrail is the element that runs parallel to the staircase; it’s used by people to maintain their balance ascending and descending the staircase and is commonly referred to as the “banister.” It should be a minimum of 36" above the nosing of the tread. The space between the wall and handrail should be no more than 1 5/8".

    A single handrail is mandatory for any staircase with three or more risers, where riser width does not exceed 43". If the staircase is wider, handrails must be installed on both sides.

    For a staircase between two walls, the handrail must be installed on wall brackets. If the staircase is open on one or both sides, the handrail becomes the upper part of the actual railing.
  1. Railing: The railing extends the length of the open sides of a stairway in order to prevent accidental falls. The railing must be at least 35" around openings and above the steps of the staircase. The spacing between balusters (or stair sticks) must not exceed 4".

Stair Dimensions and Calculations

Calculating the riser-tread ratio is essential when designing and constructing a stair. The general rule of thumb says the sum of two risers and a tread should be equal to 24" to 25". Therefore, a stair with 6½" risers needs 12" treads, while one with 7¼" risers should have 10½" treads. This relationship holds for straight, U-, and L-shaped staircase dimensions.

To calculate the number of risers in a stair, divide the staircase height (distance between the floor at the bottom of the stair to the ceiling or the hard surface above the stair) by the riser height. For example, a staircase that is 105" high can fit 15 by 7" risers. When using L- or U-shaped staircase dimensions, account for landings by subtracting one or more risers.

Tread depth and width are also key stair dimensions to note. Calculate tread depth by dividing the total length of the stair (horizontal distance between the foot of the stair and the next landing) by the number of steps. A stair should be wide enough to allow two people to pass comfortably and move furniture with ease. The standard recommendation is a minimum width of 3’. You should also use these dimensions and calculations when learning how to install stair stringers inside.

Pro tip

When measuring a stair for stringers, take care to account for the thickness of the stair tread in your calculation. This is usually 1" wide.

Building Codes for Stairs

Most residential building codes rely on the standards developed by the International Code Council (ICC) and International Building Code (IBC). These bodies provide specific stair dimensions to ensure these building features are safe for all users. Some of these rules are:

  • Stairs must be at least 36" wide with a minimum headroom of 6’ 8"
  • Risers must have a maximum height of 7 ¾" and open risers must be 4" high or shorter
  • Each tread in a stair must have a minimum depth of 10". The treads of curved staircases must not be less than 6" deep
  • Residential stairs must have nosings and these must be between 1 ¼" and ¾" in length, with the difference between longest and shortest nosings less than 3/8"
  • Residential stairs with four or more risers need handrails for safety. Handrails should be 34" to 38" above stairs. They should be at least 1 ½" clear of the wall to make them easy to grip. Handrails must also project from the wall a maximum distance of 4 ½" so they do not make stairs too narrow
  • Spaces between balusters must be less than 4" to prevent children from crawling between the openings

Staircase Building Materials

The three key factors to consider when getting materials for building a stair are durability, safety, and aesthetics. The materials selected will also help when choosing the drill that best suits you and the project. The most commonly used materials for different types of staircases are wood, natural stone, concrete, metal, steel, and glass.

More affordable than other options, wood is light, easy to work, and suitable for straight and curved staircases. It’s also warm and inviting and comes in different tones and densities. Oak is a hardwood option that is very dense and ages gracefully, while beech, ash, and maple brighten homes with their lighter tones. When building with wood, remember to apply sealant. Try a wood varnish to transform the look of your stair. One drawback of using wood for a staircase is inevitable creaking.

Natural Stone
All types of staircases made with natural stone, such as marble, have an elegant, natural look that complements luxurious decors. Stone is very strong but needs a protective coat of sealant. It’s an expensive option, difficult to use for curved staircases, and takes a lot of time and energy to install.

A less costly alternative to natural stone, concrete is also very durable. It’s easier to maintain and can look like stone with the right treatment and staining. Like stone, building stairs with concrete takes considerable time and effort.

Metals are strong materials that are lighter than wood. Often combined with wood and glass, they’re easier to shape and commonly used for spiral staircases. Aluminum is a popular metal for stairs. It’s rustproof, lightweight, strong, and malleable. Like other metals, it’s best for modern and industrial decors.

Is also suitable for curved staircases. This alloy is stronger than most commonly used metals and available in a wide range of shapes and colours. However, steel is not rustproof and needs special treatment, like anti-rust paint, to maintain its look and integrity. Stainless steel is a rust-resistant material that does not tarnish easily. Even then, it requires regular maintenance to keep it pristine.

All types of staircases built with glass look very elegant, especially when combined with stair lighting. The transparent surface of the material makes stairwells look and feel airy. It’s often combined with other materials when used only for hand rails. However, there are all-glass stairs too. Glass picks up smudges, smears, and scratches easily. It’s also a very expensive material to use for a staircase.

Staircase Flooring Options

While gathering the materials, accessories, and hardware to build a straight or curved staircase, consider the kind of the flooring it will have. The right flooring is one that is durable and easy to maintain. Here are the merits and drawbacks of common flooring options used for different types of staircases:

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