R-2 apartment open toe risers

[MK arch]

2015 IBC; R-2 aparment; three story with out an elevator, 1st floor has type "A" and "B" as required by chapter 11; 2nd and 3rd floor are only non covered units as allowed by
the exeception.

Question:
Can you have open toe riser to the 2nd and 3rd floor which contain non covered units?

 

[bill1952]

Stair risers?

 

[MK arch]

Correct.

 

[bill1952]

4" sphere rule I believe. So how high of riser and how thick of tread answer your question.

 

[MK arch]

Its your typical precast bull nose tread with a riser height of 7" and the tread depth is 3 3/8". See attached.

 

[mtlogcabin]

4 inch maximum opening

1011.1 General.
Stairways serving occupied portions of a building shall comply with the requirements of Sections 1011.2 through 1011.13

1011.5.5.3 Solid risers.
Risers shall be solid.

Exceptions:

1. Solid risers are not required for stairways that are not required to comply with Section 1009.3, provided that the opening between treads does not permit the passage of a sphere with a diameter of 4 inches (102 mm).

2. Solid risers are not required for occupancies in Group I-3 or in Group F, H and S occupancies other than areas accessible to the public. The size of the opening in the riser is not restricted.

3. Solid risers are not required for spiral stairways constructed in accordance with Section 1011.10.

 

[MK arch]

Do the non covered units (units that are not requrired to be type "A" and "B") have to comply with section 1009.3?

 

[mtlogcabin]

Yes. That section has nothing to with "A" or "B" units. It is the same as a baluster spacing requirement. If a child is trying to go up that stair he will not be able to fall through a 4" opening.

 

[MK arch]

So section 1011.5.5.3 solid riser exception #1 does not apply to a threes story, no elevator, apartment and solid risers are required?

 

[mtlogcabin]

I disagree, the third floor is an occupied space so the stairs have to meet the means of egress requirements as outlined in Chapter 10.

1001.1 General.
Buildings or portions thereof shall be provided with a means of egress system as required by this chapter. The provisions of this chapter shall control the design, construction and arrangement of means of egress components required to provide an approved means of egress from structures and portions thereof.

[BE] EXIT. That portion of a means of egress system between the exit access and the exit discharge or public way. Exit components include exterior exit doors at the level of exit discharge, interior exit stairways and ramps, exit passageways, exterior exit stairways and ramps and horizontal exits.

SECTION 1011 STAIRWAYS

1011.1 General.
Stairways serving occupied portions of a building shall comply with the requirements of Sections 1011.2 through 1011.13.

 

[MK arch]

You are saying no, you can not have open toe riser going to the second and third floor even if there are no accessible units on those floors.

 

[mtlogcabin]

I am saying Chapter 10 is for means of egress requirements and the stair requirements are for all occupancy types.

Exception 1 to the solid riser requirement permits a maximum opening of 4 inches in a stair riser.
Which is exactly what your post #5 drawing depicts and we see a lot of around here on apartment buildings.
A riser opening greater than 4 inches is not permitted in an area used by the public as outlined in Exception #2


2. Solid risers are not required for occupancies in Group I-3 or in Group F, H and S occupancies other than areas accessible to the public. The size of the opening in the riser is not restricted.