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Stair Step Dimensions

Staircase Step Dimensions


Richard A. Acree

Staircases seem to always be a part of Nashville Tennessee Home Inspections completed by HABITEC Home and Building Inspections, LLC. In older homes staircases can present a problem when it comes to dimensions. Look at the picture below. Does this look OK? 

In the picture you are looking down the staircase leading to a basement in a house about 100 years old. 


In the picture to the left is a closeup of the stairs while standing in front of the stairs in the basement.

ANSWER: It is hard to know for sure without using a tape measure, but these stairs are very steep and therefore present a falling hazard. Look at the pic below to see the measurement of the step rise. Almost 9 inches!

The pic to the right shows the step run, or horizontal measurement. Less than 8"!

Proper step rise and run dimensions are shown below in a drawing from Code Check. Most municipalities use IRC numbers. In this staircase, both dimensions are wrong. If either measurement is inadequate the Client for the Home Inspection needs to know because this presents a safety hazard. When both dimensions are wrong, this is a serious falling hazard. So the answer is NO, this is not OK.

The issue in this case is one of installation. At the time of installation, many years ago, this was probably acceptable. In today's world, we know better now and stair step dimensions have been changed to be safer.

Another situation we see involves stair systems at the exterior of the house. Look at the picture below. From a distance it may be hard to see the issue with the steps. For a hint, compare the rises of each step going from bottom to top step.

You should be able to see that the lower step is only about a 4" rise. The middle step is about 7". But the top step, up onto the porch, is huge. Look below for a closeup.

That flashlight is approximately 11" long! So we have gone from 4" to 11" in height variations. That is pretty tough sledding even in daylight conditions, but imagine what this would be like at night. This step system has dropped so much the railing on the right has disconnected and there is a 2" gap between the rail and the step.

So this step rise is in excess of the recommended 7.5" normally seen. And the variation is also way out of limits. Stair rises should not vary by more than 3/8", whatever the rise. That way, when people are maneuvering up or down the stairs their mind is aware of an expected rise for each step. If that rise varies, the mind won't know it until the foot has already missed the mark, and down you can go.

This problem was not created at installation though. This problem was created by settlement. The water management system around the house deposited water at the foundation and allowed many components, including the foundation, to drop or fail. first fix the water management system, then repair the steps.

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Thank you,

Richard Acree

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