This is an unfortunate error by the designer and/or the builder both of whom should have known better. The total rise should have been held to between 21" and 22 1/2" so the risers would be between 7" and 7 1/2" tall. With a total rise of 24" your riser options are 4x6" or 3x8". Most building codes do not allow a riser taller than 7 3/4" but some jurisdictions modify the code to allow 8 1/4" risers. An 8" riser will work fine except for the very young, the elderly or the handicapped. Double handrails (one high and one low) on both sides of the stair usually remedies this problem. What determines comfort for each option is the depth of the tread measured from face to face of the risers. You have arbitrarily selected a 10 1/2" tread which is what would have been appropriate for the 7 1/4" riser your designer should have specified. For an 8" riser that tread dimension should be 9" and for a 6" riser it should be 13". At 10 1/2" each of the riser options would produce a theoretically awkward and possibly dangerous stair. However, since there are so few steps the danger is much less than for a full flight of stairs so choose which ever you like best but you should try each of them first. 8" risers are common in older houses especially for basement stairs and 6" risers are usually found outdoors. A turn in the stairway will create an interruption in stride which will relieve the awkwardness of the stair.

The Stairway Manufacturers Association Visual Interpretation of IRC 2006 does not show any maximum run lengths for stairs. Space, i.e. tight square footage, is what usually drives the size, placement and configuration of the stairs - and often many other decisions in home planning and building. Folks are always looking for ways to squeeze more house out of less space. Unfortunately, safety, flow and ease of use are often overlooked in the pursuit of less square footage. Stairs, hallways, closets and bathrooms are easy targets - they are a often viewed as necessary evils that Âeat space rather than being embraced as features that can make a home function and live more efficiently and comfortably.

Using the bizarre code amendment in effect for your jurisdiction and assuming the floor to floor height is approximately 108.5" (because the contractor recommended 7.25 risers and he should know the actual total rise), you have a choice of 14 risers @ 7.75" or 15 risers @ 7.23" (but you should ask the contractor for the floor to floor height instead of guessing). The most comfortable tread "run" for these two options would be 9.67" and 10.36" (the tread gets longer as the riser gets shorter). Adding a 1.25" nosing makes the tread surfaces 10.92" and 11.61" both of which meet the 10" oddball code minimum but I would use a shorter nosing. So, compared to the above optimal design, the original contractor recommendation of an 11" tread was 5/8" too short if he was using the applicable code definition of "tread" and it was 5/8" too long if he was using the IRC definition of a "tread". Either way his design was not based on any reasonable rise/run ratio. If you use the 14 riser stair the risers will be between 7.65" and 7.75" which is a bit taller than an ideal stair so you should measure the stairs you are used to climbing and the stairs of your relatives and friends and think about how this riser height would feel. That would give you a tread "run" of 9.67" to 9.77" so with a nosing of 1.25" the tread surface would be 10.92" to 11". Since the applicable code amendment removed the IRC definition of "tread depth", it is clear that the definition was intentionally left up to the building official so there is little or no risk of someone challenging the stair design later. Just make sure the stair riser and tread are drawn to scale and dimensioned in a blow-up detail on the permit drawings not just noted on the plan. This is the oldest and most reliable stair design tool I have found. Tread dimensions are without nosings.

"No, they have to build to code. When it comes to stairs, approved drawings are more like suggestions." Well, they should be accurate, but I really do not see many architect drawn plans that are. Case in point, ILoveRed's plan is only accurate on the 2nd floor plan. Appearantly, you are allowed to loose a tread for each lower level you draw. It also bugs me that they tend to spec stairs at code minimums. I have never drawn plans with less than a 10.5 inch tread run, 10.75 or 11 when convenient. I am also almost always able to stay under a 7" rise because I simply figure out how much room is necessary before I draw the rest of the house. If I were actually involved with this plan as a GC, I would have made sure the plan was corrected to a max 7" rise, and min 10.5 run before it was finalized. If I was not involved until after the plans were approved, I would have drawn out a few alternatives before construction started to explain what can be done at that point to fix the steep stairs, and most of them would have proper winders that feel good, not that 45° corner nonsense.