How to Build Stairs

Here are the basic principles to get you started

Entrance hall of residential home
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Building stairs doesn't have to be difficult, but it does require precision and attention to detail. Whether your need is for a short flight of functional steps to a deck or front porch, or an interior staircase leading to a sleeping loft or mezzanine, the same four basic principles apply—codes, design, measurements, and construction.

Codes

Stairs in older homes were frequently steep and narrow, making them difficult to climb and made moving furniture upstairs even more difficult. As a result, safety needs and building codes now address risers and treads in detail and effectively prohibit the cramped staircases once common in historic homes. Codes also address stairway width, head height, railings, banisters, and landings. Always check local requirements before starting, because some jurisdictions have adopted different code provisions with varying requirements. 

Code for Open Risers

If you're considering open risers, note that The International Residential Building Code allows them—also called "see-through" steps—only if the openings "do not permit the passage of a 4-inch-diameter (102mm) sphere."

Design

Whether it's an indoor or outdoor staircase, the design and material choice comes next. You'll find plenty of design solutions for both traditional or modern staircases.

For contemporary interior stairs, open staircases with no walls and artistic handrails are popular. Combining industrial materials such as steel or wrought iron with wood produces beautiful, strong, and functional staircases. Open tread stairs, without a solid wood riser, are trendy, and modern treads can be anything from specialized wood to clear, thick acrylic.

For traditional outdoor steps, weather-resistant redwood or cedar are ideal materials for a traditional look. Requiring minimum upkeep, they will naturally fade to gray or can be stained or painted. Treated lumber is more cost-effective, and it too can be stained or painted but may require periodic refinishing.

Measurements

Building any set of stairs, even if it's only a two-step from the patio to the garden, involves detailed planning. Once you finalize your stair's plans to code, the only requirement is to be diligent about the calculations so that the finished design is functional, attractive, durable, and safe.

Consider the Thickness of Finishing Materials

Finish materials affect the measurements of steps. For example, if you plan tiled or carpeted and padded steps, those thicknesses must be considered when planning the stairs.

Interior Steps

Measure the height of the flight from the first floor to the finished floor level of the second story. Consider the width of the staircase, usually a minimum of 36 inches for interiors. Find out whether a railing will be required. Handrails are only necessary on one side of a residential staircase.

Exterior Steps

For outdoor steps, measure the distance from the porch or deck to ground level. For exterior stairs, railings are often required when there are four or more steps. However, there are exceptions, so check with your local regulatory office for details.

Risers and Treads

Most people appreciate the comfort of stair treads that measure at least 12 inches from front to back. With the addition of a 1-inch bullnose edge, the actual depth could be a generous 13 inches or 14 inches. Here are a few more typical measurements:

  • Riser height: Risers should have a minimum height of 4 inches to a maximum of 7 3/4 inches. Typically, a height of between 6 inches and 6 1/2 inches is both functional and comfortable for an interior staircase.
  • Tread length: Tread lengths should be a minimum of 10 inches to 11 1/4 inches.
  • Tread depth: If a 12-inch depth isn't an option, it's typical to have the required minimum tread depth of at least 10 inches, plus a "nose," or edge, of between 1 inch to 1 1/4 inch.

Riser and Tread Variations

Riser heights are allowed to vary only by 3/8 inch from one step to another. Tread depth must be consistent, as nearly equal as possible.

Construction

Unless your stairs are poured concrete, a sturdy support system is necessary. Wood "stringers," with cuts that look like a saw blade, are the most common. They are securely bolted to the bottom surface as well as the upper floor or deck level, forming the two outer edges of the staircase, and are usually constructed from 2-foot by 12-foot pieces of lumber. 

Wooden risers are attached to the stringers' vertical surfaces. The treads are securely screwed to each horizontal level, forming what appears to be a stepped box. If the staircase will not be totally enclosed, sometimes straight-edge supports replace the sawtooth stringer, and the horizontal treads are bolted to the supporting edges, or attached by slotted metal connectors for a modern industrial look.