Here are the minimum code requirements for residential stairs:
• The stair riser (vertical piece) cannot exceed 7-3/4-inches in height (IRC R311.7.5.1)
• The minimum tread (horizontal piece) depth is 10-inches.
• A nosing is required on treads that are less than 11-inches long (IRC - R311.7.5.3). See When is a nosing required on a stair tread? for full details.
• The steepest stair allowed has 7-3/4-inch risers and 10-inch treads, but the treads require a nosing.
• The longest stair run allowed has a maximum of 147-inches (12’-3”) of vertical height between floor levels or landings.
• Stair headroom cannot be less than 6-feet 8-inches, as measured vertically from the sloped line adjoining the tread nosing or platform on that portion of the stairway (IRC R311.7.2).
• Headroom for spiral stairs can be slightly less, at 6-feet 6-inches (IRC R311.7.10.1)
• A landing is required at the top and bottom of stairs that is at least the width of the stairs and minimum 3-feet deep (IRC R311.7.6), with two exceptions: 1) A landing is not required at the top of an interior flight of stairs, including stairs in an enclosed garage, provided the door does not swing over the stairs [IRC R311.7.6(1)], and 2) A landing is not required where a stairway of two or fewer risers (one tread) is located on the exterior side of an exterior door. (FBC R311.3.2)

• Interior stairs with six or more risers require lighting that is 3-way switched at top and bottom landings. Exterior stairs require lighting at the top landing that is switched from inside home. (IRC R303.7 and R303.8). Go to What is the lighting requirement for stairs? for full details.
• Receptacle outlets are not required at stairs or stair landings.
• Open risers are allowed, as long as “the opening between the treads does not permit the passage of a 4-inch diameter sphere” (IRC 1011.5.5.3).
• A handrail is required for a stair with four or more risers, must be at least on one side of the stair, and 34-inches to 38-inches above the tread (IRC R311.7.8). There are multiple other requirements you can read about at What are the building code requirements for a handrail at stairs?

     These requirements are based on the International Residential Code (IRC) and the National Electrical Code (NEC). Other codes and local jurisdiction amendments may be different. Also see Frequently Asked Questions (FAQ) about Minimum Code Requirements

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Here’s links to a collection of our other blog posts about BUILDING CODES:

• What are the minimum code requirements for a residential bathroom?

• What are the minimum code requirements for a residential garage? 

• What are the minimum code requirements for a residential kitchen? 

• When did the first Florida Building Code (FBC) begin and become effective?

• The home inspector says I have construction defects. How did my home pass inspection by the building department? 

• What is the difference between prescriptive and performance building codes?

• Can a local building department choose to not enforce selected parts of the Florida Building Code? 

• Is the latest edition of the National Electrical Code (NEC) the standard used for the electrical system of new homes?

• Why is the National Electrical Code (NEC) so hard to understand and complicated? 

• What is the purpose of the Existing Building Edition of the Florida Building Code?

• What is the most important sentence to know in the entire National Electrical Code (NEC)? 

• How often does the National Electrical Code (NEC) change?

• Does a home inspector look for code violations? 

   Visit our STAIRS page for other related blog posts on this subject, or go to the INDEX for a complete listing of all our articles.