The building code is the same for both interior and exterior steps: a handrail is required for 4 or more risers (3 treads). Here’s the citation in the Residential Edition of the Florida Building Code (FBC), and the International Residential Code (IRC) is the same:

     This is a summary of the other handrail requirements found at R311.7.8:

• Handrail height must be 34 to 38 inches high, measured from the tread nosing or ramp surface, with two exceptions allowed: 1) a volute (shown below) is allowed over the lowest tread, and 2) the transition from handrail to guard, or at the start of a stair flight, my exceed 38 inches.

• Handrail should be continuous for the full length of the stair flight, from above the highest riser to above the lowest riser, but can be interrupted by a newel post.

• Handrails ends should be returned to the wall or terminate at newel post or safety terminal. The handrail shown at the top of the page is an example of one that is not terminated properly and the end sticking out could snag a handbag, causing a fall.

• Handrails next to a wall must have a minimum of 1.5 inches between wall and handrail.

• A round handrail diameter must be between 1.25 and 2 inches. If handrail is not round, the perimeter should be between 4 and 6.25 inches, and have edges slightly rounded with a diameter of at least 1/100th of an inch. 

• Handrails with a perimeter of more than 6.25 inches must have a finger-grippable recess on both sides. The requirements for the shape and recess are very specific: "The finger recess shall begin within a distance of 3/4 inch (19mm) measured vertically from the tallest portion of the profile and achieve a depth of not less than 5/16 inch (8 mm) within 7/8 inch (22 mm) below depth shall continue for not less than 3/8 inch (10mm) to a level that is not less than 1-3/4 inches (45mm) below the tallest portion of the profile. The width of the handrail above the recess shall be not less than 1-1/4 inches (32 mm) and not more than 2 3/4 inches (70 mm). Edges shall have a radius of not less than 0.01 inch (0.25 mm)."

     Here’s some examples of both acceptable and rejected handrail profiles from the folks at Code Check®. 

    When the steps are more than 30 inches above ground there must also be a guardrail. See our blog post What is the difference between a handrail and a guardrail? 

    And, finally, this is an example of the wrong way to do a handrail.

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

• What is the minimum headroom clearance for stairs?

• Is a landing always required at the top and bottom of stairs? 

• Are open risers alright at outside steps and stairs?

• When is a railing required at stairs?

• What is the building code for the minimum height of stair steps (risers)? 

• When is a nosing required on a stair tread?

• What is the building code requirement for receptacle outlets at stairs and stair landings?  

• Are open stair risers acceptable?

• What is the steepest residential stair allowed?

• Why is a single step dangerous in a house?

• Do I need stairs at all exit doors from a mobile home? 

• The stairs feel too steep. What's the building code? 

• What do home inspectors check when inspecting stairs?

• What is the longest stair run allowed? 

• What is the lighting requirement for stairs?

• A light is required over a stair after how many steps/risers? 

• When is safety glass required for windows at stairs and stair landings?

• What is the difference between a handrail and a guardrail? 

    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.