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.

Renovator8: Thanks for the response. I'm a little confused, and it may be because I have caused the confusion. The depth of the stair is 21" -- that is, when I put my foot down on a stair step, it would be on area that is 21" from toe to heel. So i'm confused about it being called a 10 1/2" tread.

And this is my own idea and it is still in the design phase, so no separate designer to blame (on this issue) but me.

What I was trying to create was the more gradual, less steep, type steps I have seen in landscaping. But I don't want it to be awkward. Maybe I need to try a mock up.

The "run" of a stair is the total horizontal distance of all of the steps without counting the nosing (overhang of the step).

I assumed 21" was the total run of the two steps so the distance from the face of a riser to the face of the next riser would have been 10 1/2". When designing a stair this dimensions is referred to as a "tread" even though the finished stair might have a nosing added. The finished size of a tread with a nosing is never used when designing.

If each step had a "tread" dimension of 21" the stair would be dangerous and uncomfortable to use. People walk faster up a stair outdoors so they have lower risers and longer treads. That will not be the case in your home but if you stick to the proper ratio people will be less likely to trip. Separating the stair into two runs by turning it makes it more dangerous. A stair less than 3 risers high is difficult to see and adjust your stride to.

Make each "tread" 13" to 14" and then add a 1" nosing (not required by code for such a large tread) to achieve an "outdoor" stair profile. That will be strange inside a home but reasonably safe. Put a handrail each side of all of the steps.

nvmd

This post was edited by chris401 on Sun, Jan 12, 14 at 23:04

I thought a garage needed to be lower than the adjoining living space in order to keep heavier-than-air toxic fumes (like gasoline) from entering the house?

I'm not an expert, but I believe code requires a curb that keeps liquids from entering the living space. So if there was a gasoline leak or similar. This garage will have a typical 2-3" curb.

Not sure on the toxic fume issue. Have not heard of that.

The curb requirement is no longer in the IRC but it might be in older or local codes.

The drawing is confusing and uses non-standard drafting conventions. The American drafting convention is to show the direction of a stair from the main level so if the garage is higher than the main floor there should be an arrow pointing from the bottom riser of the stairs to the top riser and a note at the main level indicating the stair goes "UP".

Does the stair have 4 risers? What is the line at the mudroom door?

I would expect an architect prepared drawing to have much more information on it.

The garage has a finished floor elevation at +2' -- I guess the architect thought that would indicate stair up/down. But sounds like he didn't follow convention.

There are four risers. The line at the mudroom door says "CJ" which stands for control joint. The flooring is finished concrete, so he indicated where to put control joints.

Thanks for commenting.

This post was edited by chris401 on Sun, Jan 12, 14 at 23:07

It would help if you posted a plan that is large enough that the notes could be understood and the space in question could be scaled. Did the architect not draw plans for construction with dimensions?

Two handrails will be essential but there seems to be something to the side of the stair that might prevent a railing there.

Spaces should be designed around properly designed stairs rather than the reverse which seems to have happened here. It seems to be a little late to be tuning up stairs.

I have to ask if the architect is licensed; not to be impertinent but in an attempt to redeem the reputation of my profession.