AskCodeMan

FBC requires stair width of 44''.
Is that width measured from inside of stringer to inside of stringer?

That width is measured at the handrails and is to be maintained above the handrails to the headroom height of 6 feet 8 inches.

The handrails are permitted to project into the stair width from each side, but from the top of the handrails up the minimum width is required.

At handrail height and below, the width is permitted to project into the required stair width not more the projection of the handrails.

I was not able to access the code earlier, here are the code references
- From the 2010 FBC:
- - 1012.1 Where required.
- - - Handrails for stairways and ramps shall be adequate in strength and attachment in accordance with Section 1607.7. Handrails required for stairways by Section 1009.12 shall comply with Sections 1012.2 through 1012.9. Handrails required for ramps by Section 1010.8 shall comply with Sections 1012.2 through 1012.8.
- - 1012.8 Projections.
- - - On ramps, the clear width between handrails shall be 36 inches (914 mm) minimum. Projections into the required width of stairways and ramps at each handrail shall not exceed 4 1/2 inches (114 mm) at or below the handrail height. Projections into the required width shall not be limited above the minimum headroom height required in Section 1009.2.

1012.8 references 1009.2 Headroom, which addresses the 80" - 6' 8" - minimum headroom.

44" minimum stairway width less 4 1/2" in from each side equals 44" less 9" or 35" minimum between stair handrails "at or below the handrail height", per 1012.8

Above the tops of the handrails the minimum stairway width of 44" is maintained to a minimum height of 6' 8" (minimum headroom height of 80")

Hope the code references helps also.