Consistent step heights prevent injury.
There are some pretty strict building code requirements when it involves stair construction. The number of accidents that are caused by improperly constructed and maintained stairs are staggering. One of the important requirements is the consistent height of the steps.
According to the 2010 California Building Code, stair riser height shall be a maximum of 7” and a minimum of 4”. All steps in any flight of stairs must all be within 3/8” of all the other steps. The reason for this code is simple, if the height of steps varied greatly from step to step; there is a much greater chance of someone falling and being injured.
This consistent step height can change if stairs begin to sag or are improperly repaired. It is a good idea to check for a uniform step height if your stairs have changed. To protect yourself, it may be wise to hire a professional contractor for repairs and an inspector to check the final product.