Residential Stair And Handrail Code (2020 IRC Guide)

Are you interested in learning the latest IRC stair code for residential homes?

Stairs are an important way to exit a home level and to escape a hazard --- such as a fire.

In this guide, I will go over...

  • the basics of stairway code such as treads, risers, and guardrails
  • common safety issues with stairs
  • what home inspectors look for

Let's get started with this guide!

residential stair code

What Is The Residential Stair Code?

The residential stair code is a sub-section in the Means of Egress section of the International Residential Code handbook in Chapter 3 entitled Building Planning. 

Chapter 3: Building Planning >> Section 311: Means of Egress >> Sub-Section 311.7: Stairways

Technically, stairs is considered a 'means of egress' which basically means a way to escape from a home (or level of a home). The IRC is updated every 3 years, and the last update was in 2018. This guide isn't meant to be exhaustive of every single code in the IRC, but it is meant to present the basics and what I think is the most important.

Sometimes when we do a DIY job, such as building stairs, we spend a lot of time and money — and then end up hiring a pro to fix our mistakes. That's why I created my Contractor Search Tool, so my readers can get free quotes from local contractors who are licensed and pre-vetted.

I invite you to at least see the pricing for any home project from a few trusted contractors—there is no obligation—and then you can decide whether to go ahead with a DIY job. Get your free quotes with my contractor search tool right here.

Stairway Width

The stairway width above the handrail and below the minimum headroom height shouldn't be less than 36 inches.

Below the handrail, the width should be at least 31.5 inches if there is one guardrail.

If there are guardrails on both sides, then the minimum width should be 27-inches below the guardrail top height.

stairway width residential stair code (1)


Headroom is the space required from the stairs to the top. Basically, this rule helps prevent people banging their head on ceilings.

I recently did a home inspection on an old home with numerous additions. The stairs to the basement had a ceiling protrusion that was probably around 5 feet and I repeatedly hit my head on the top. Ouch.

The minimum headroom as measured from the stairs to the top should be at minimum 6-ft and 8-in.

minimum headroom residential stair code


Riser height should have a maximum height of 7-3/4 inch height. There shouldn't be a height difference of more than 3/8" between the tallest and shortest riser.

Open Risers

If the stairs has open risers, then anywhere above 30" from floor should not permit a sphere of 4-inch diameter to pass through. Basically, if there are no risers, then a child's head shouldn't be able to pass through above than 30" point from ground.


The treads (horizontal portions) of a stairs should be at minimum 10-inches. The longest tread versus the shortest tread shouldn't be more than 3/8-inch.

That basically sums of the basics of the stairs rise and run code.

riser and tread length residential stair code

Read Also: Tips & Traps When Buying A Home


The stair railing height code in the IRC states that the minimum height is 34-inches and the maximum height is 38-inches. The top of the handrail is measured from the stair nosing, as if you drew a diagonal line across the top of the stairs.

handrail residential stair code 2
handrail residential stair code

What Do You Look For As A Home Inspector?

During my home inspections, the most common areas that I cite in regards to stairs come down to just a few items. 

And by the way, my favorite book on code is by DeWalt called Residential Construction Codes.

Residential Construction Codes is the complete guide to the 2018 residential building codes. It is highly readable and has great illustrations. It also includes those weird code exceptions that even code enforcers screw up.

You can view the price of Residential Construction Codes on Amazon right here.

1. Four Inch Sphere

Anywhere above 30-inches from the ground, there needs to be a guardrail to prevent a hazardous fall for an adult or child. In the home inspection world (and the IRC), there is a rule known as the four inch sphere rule.

Basically, it means that a 4-inch sphere should not be able to pass through the handrail. The 4-inch sphere is equivalent to the head size of a small child. If the child's head can get through, then their whole body can get through.

stair rail code safety four inch sphere rule

2. Loose Railing

Many times when I push on a railing, it is very loose. Most indoor stair handrails have a little give, but if it is obviously loose, I will call it out. For decks or hallways, the guardrail is more significant since numerous people may be leaning on the railing such as at a party.

3. Missing Railing

It never ceases to amaze me that a stairway can have a missing handrail, but it happens. Remember, any time you can fall more than 30" inches, there should be a guardrail.

4. Missing Lighting

Stairs should always have illumination for obvious reasons. If you are always going up and down stairs without lights, sooner or lighter you are going to take a fall. Stairs with more than six risers should always have a light switch at the top and bottom --- a three way switch.

Sometimes when we do a DIY job, such as building stairs, we spend a lot of time and money — and then end up hiring a pro to fix our mistakes. That's why I created my Contractor Search Tool, so my readers can get free quotes from local contractors who are licensed and pre-vetted.

I invite you to at least see the pricing for any home project from a few trusted contractors—there is no obligation—and then you can decide whether to go ahead with a DIY job. Get your free quotes with my contractor search tool right here.


There you have it, the basics of the IRC stair code. And again, the IRC is updated every three years, but usually the basic code remains the same. This guide isn't meant to present every single stair code --- there are NUMEROUS exceptions stated in the actual IRC stairway section. 

To really get the final word on any residential code, you should always go to the actual source such as the IRC website.

However, don't forget that state, county, or city codes may supersede the IRC.

Read Also: Venting A Bathroom Fan Into An Attic

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9 thoughts on “Residential Stair And Handrail Code (2020 IRC Guide)”

  1. What is the code for the placement of the Newell post(s) At the top of the stairs, relative to the floor level stair nosing?

    • Hey Noah,

      The IRC only mentions newel posts in one small area, “R311.7.8.4 Continuity” and describes that the railing has to terminate in either a newel post, returned to the wall, or a safety terminal — basically to prevent peoples clothing from getting caught on railing in case of fire/emergency.

      It never mentions nosing, only the riser.

      It states that the end of the railing (newel post) at minimum needs to terminate “directly above the top riser”.

      My homes top newel post actually overlaps the edge of nosing and the riser line. If at least part of the newel post is directly above the riser line, I think you are good to go.

      Good luck!

  2. I am installing a 2 round railing for my outside steps . If I dont hit a stud will the partical board be strong enought to support the railing and the people using it?

    • Hi Ardell,

      I don’t think such an installation would be to code. In section R301.5, its says that a “concentrated load applied in any direction at any point along the top” of 200 pounds per square foot for guards & handrails. I wouldn’t settle for an OSB wall connection.

      Good luck!

  3. Hi Arie,
    We recently constructed a small loft under the sloped ceiling of our living room. It’s about 6 feet off the ground, and the ceiling ranges from 26 inches – 36 inches above the floor of the loft. We were thinking of putting a ladder up against it and making it a hangout space for our kids. I’d put a railing up there for them of course, but I’m wondering about the minimum height of the railing since the ceiling is so low. (I’d prefer to keep it around 26 inches and not run the balusters up to the ceiling). I’m also wondering if there are any other code requirements to worry about with the ladder leading up to the loft. Or if you think an inspector would have an issue with this idea altogether! Thanks for your advice!

    • Hi Kelly,

      There would be a few code violations such as minimum ceiling height and minimum guard rail height. However, if you call that area a non-habitable storage area — it may exclude your from most of these codes to be honest. As home inspectors, we aren’t allowed to cite code violations in our home inspection reports, only government inspectors are allowed to call out code violations.

      Personally, I wouldn’t worry about it.

      Good luck!


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Arie Van Tuijl

Arie Van Tuijl

Arie is the founder of Home Inspector Secrets, an online resource dedicated to helping people understand how homes work. He is a licensed home inspector in two U.S states and owns a residential and commercial inspection company (read his full bio on the About page). To ask Arie a question, please use the comment box at the bottom of the relevant article.

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