Originally Posted by Daniel Holzman
There are very explicit standards for step height (the rise) and step width (tread). There are minimum rise and tread, and maximum rise and tread. Your building inspector should be very familiar with the requirements in your area, I would check with them. In addition to minimum and maximum dimensions for rise and tread, there is generally a requirement that all steps be the same rise and tread, within a narrow tolerance, usually not more than 1/4 inch difference between each step. Again, your building inspector should be able to go over the rules with you.
Can't speak for everywhere, but here in WI:
- There is a max. tread height, yet there is NO minimum.
- There is no maximum thread depth on an exterior porch.
- Steps need to all be within 3/8" tolerance of each other, BUT when a landing exists (3' min. equals a landing) between those steps, the tolerance is non-applicable.
To answer the OP's question, the answer is subjective. IMPO, any step less than 4" is what we call a "stumbler". If you only have one from a landing (the stoop) into the first floor, it's certainly less dangerous. That being said, we still try to match riser heights as often as possible.