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Stair Basics

vatcan stairsThe stairway in commercial occupancies that do not meet code can lead to injuries.  Over the years the dimensions for stairway tread and risers has changed.  These changes have occurred due to the information gained on injuries.  So do you know some of the basics for stairways?

Chapter 10 of the International Building (or Fire) Code provides the code requirements for new construction.  Section 1009 provides specific direction on stairways.

Definitions

Stair: A change in elevation, consisting of one or more risers.

Stairway:One or more flights of stairs, either exterior or interior, with the necessary landings and platforms connecting them, to form a continuous and uninterrupted passage from one level to another

The stairway width shall be a minimum of 44″.  Section 1009.1 provides four exceptions on the width (occupant load less then 50, spiral stairways, aisle stairs, etc.) with a minimum headroom shall be 80″.

For most stairways the tread depths shall be 11 inches minimum and riser height shall be between 4 and 7 inches.   Stairway treads and risers must be uniform in size and shape (variance of 0.375″ between the max and min).  The structural materials shall be consistent with the materials of the building.

If there is a door associated with a stairway, there shall be a landing or floor space on both sides of the door.  The height on both sides of the door shall be the same height on each side of the threshold.  A variance of 1/2″ in is allowed when different materials are utilized.

There are many considerations including handrails, landing widths, and the enclosures stairs may need to be in.  Have you found non-conforming stairs that do not meet the code?

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