Minimum Stair Width for All Purposes

Properly measuring all your home elements is crucial, especially when discussing minimum stair width. This standard wasn’t established arbitrarily; it’s fundamental to ensuring stair safety. Overlooking these guidelines can result in long-term hazards.

The staircase’s main purpose is to deliver you from one-floor level to another one. It also has another purpose: an aesthetic component for your home. Sometimes, the measurement can be slightly different when discussing aesthetics than the rules.

But, as a responsible homeowner, we should not ignore the standard measurement to ensure stair safety without ignoring your home’s aesthetic function.

A different kind of building has a different measurement, for example, the measurement for a residential building compared to a commercial building measurement. Different standards used can also lead to different numbers of measurements.

This time, we will talk about the measurement of the stairs for residential and commercial buildings and the IBC standard measurement.

Minimum Stair Width Residential

The most common and efficient method to traverse floors in residential buildings is through stairways. Some may have more budgets to install an elevator in their home, but it is not usual. 

A residential building is where people live as opposed to industrial or commercial buildings. That’s why using a safe stair measurement will ensure more safety for those living there.

Minimum Stair Width Residential

The standard for the residential stairway comes from the International Residential Code or IRC. IRC is an independent residential code that decides the minimum measurement for one and two-family buildings with three stories or less. The number must be obeyed to ensure the safety of the building.

Per the 2012 IRC, for basic stairs with one handrail is at least 31.5 inches and 27 inches for stairs with two handrails. A minimum width of 36 inches for spiral stairs is mandated to comply with IRC standards.

Minimum Stair Width Commercial

Commercial buildings are a building that is intended for commercial use. This includes office buildings, warehouses, or retail buildings. A little different from the residential building, commercial building’s main purpose is to do business rather than live daily.

Minimum Stair Width Commercial

The standard used for the measurement can vary from the International Building Code (IBC) to the Occupational Safety and Health Administration’s (OSHA) Fixed Industrial Stair regulations. Both standards must be done correctly to ensure the safety of the stairs. If the minimum requirements are not fulfilled, safety will be compromised.

Both IBC and OSHA specify a minimum stair width of 22 inches. This dimension considers both safety and efficient use of resources.

Minimum Stair Width IBC

IBC, the standard of measurement in stair width, has been mentioned above. The International Code Council (ICC) is responsible for creating the codebook. Several countries, like the USA, Saudi Arabia, Afghanistan, and others, have implemented the standard.

The IBC regulation pays attention to the buildings’ health and safety. The code intends to provide safety while also avoiding unnecessary costs in the process.

Minimum Stair Width IBC

The code regulation was printed in the codebook with over 700 pages. The codebook tells us about building occupancy classifications, heights and areas, interior finishes, foundation construction, etc. Now, we will talk about stair regulation, especially the stair width measurement.

According to the IBC, stairways must be at least 36 inches wide. This measurement is applied for stairs with an occupant of fewer than 50 people. If the building is open to the public, obeying IBC guidelines is a non-negotiable requirement.

Building stairs is necessary for a building with two stories or more. Building a safe stair is necessary to ensure safety for the people who stay there. There are differences in measurement used for different kinds of buildings. Residential buildings and commercial buildings is different from one another; alas, they have different measurements.

  • Riser Height and Tread: The balance between riser height and tread depth is vital. The riser height, measured vertically, should not exceed 7 ¾ inches, with the tread depth at least 10 inches. This ensures comfort and safety in flights of stairs.
  • Stair Rail and Safety: A stair rail or handrail is essential for stairs with a vertical rise of more than 30 inches within 12 feet of horizontal distance. The rail should be at least 34 inches high but not more than 38 inches, measured vertically from the tread nosing.
  • Space Considerations: In areas with restricted space, a minimum of 20 inches may be considered for secondary stairs or utility stairs not serving as main stairways.

Many regulations can be used for reference in finding the minimum value. IRC, IBC, and OSHA are some of the regulations that are commonly used for reference. This regulation aims to provide safety for the building while also cutting the unnecessary cost of building it.

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HomeTips is an experienced author and expert technician. With years of practical experience in the field authored several informative articles on various aspects related to home improvement, including installation, maintenance, and repair.