Occupancy separation and Area Separation IBC Section 508

[Jgilmore29]

Hello All, I have a 5 story building Construction type III-B Sprinklered.
On my Ground Floor I have a Restaurant Space#1 (A-2 occupancy) and a Office Space #2 (B-occupancy) both are separated with a corridor.
Floors 2-5 are Residential Units (R-2).
My question is describe occupancy separation and area separation per IBC Section 508. What would my corridor be what occupancy at ground floor.

 

[steveray]

Hunh....2 stairs and neither one discharge to the exterior and don't seem like they are far enough apart.....

If the building is over area for the use and construction, you can put in a firewall to "reduce the size of the building".....If you are just separating uses, you can use a fire barrier which is easier to build.....

Thats is a really complicated building for your first post....Welcome to THE forum!

 

[Yankee Chronicler]

steveray is correct. The two stairs are not sufficiently remote. The one on the left could be made to discharge to the exterior IF the corridor it dumps into is constructed as an exit passageway. However, if that's an exit passageway, the trash room can't open into it. But that doesn't solve the exit remoteness issue.

Please post the second floor plan.

 

[Jgilmore29]

Here is the 2nd-5th floor R2
Yes the Stairway on the left does discharge to the exterior. The stairs apply to the 1/3 of the main diagonal apart.

 

[Yankee Chronicler]

What does the diagonal hatch in the walls immediately surrounding the stairs indicate? My assumption was that it indicates the rated stair enclosure, which means that the discharge passageway for the stair on the left isn't rated. It has to be. And since the code doesn't allow not-normally-occupied spaces to open into exit enclosures, the door to the trash room can't open into that exit passageway.

The upper floor exit diagrams measure the exit access travel distance incorrectly. It should not be measured diagonally in rooms or spaces that will have furniture.

What's the maximum diagonal dimension of the floor plate, and what's the distance between the two stair doors?

 

[steveray]

And while you are removing the trash room from the exit enclosure, you are going to want to put a door at the bottom of the stairs:

1023.3.1 Extension​

Where interior exit stairways and ramps are extended to an exit discharge or a public way by an exit passageway, the interior exit stairway and ramp shall be separated from the exit passageway by a fire barrier constructed in accordance with Section 707 or a horizontal assembly constructed in accordance with Section 711, or both. The fire-resistance rating shall be not less than that required for the interior exit stairway and ramp. A fire door assembly complying with Section 716 shall be installed in the fire barrier to provide a means of egress from the interior exit stairway and ramp to the exit passageway. Openings in the fire barrier other than the fire door assembly are prohibited. Penetrations of the fire barrier are prohibited.

Unless these truly are exit access stairs (as labelled) and that is a whole different ball of balls....Which edition of IBC are you using and are you the designer?

But we can try to get back OT now....

 

[Jay Smith]

The ground floor could contain nonseparated occupancies per 508.3. The occupancy in each ground floor tenant space will probably change from time to time. The occupancy separation would be Level 2, because Group A-2 would otherwise restrict the number of stories.

 

[Jgilmore29]

What does the diagonal hatch in the walls immediately surrounding the stairs indicate? My assumption was that it indicates the rated stair enclosure, which means that the discharge passageway for the stair on the left isn't rated. It has to be. And since the code doesn't allow not-normally-occupied spaces to open into exit enclosures, the door to the trash room can't open into that exit passageway.

The upper floor exit diagrams measure the exit access travel distance incorrectly. It should not be measured diagonally in rooms or spaces that will have furniture.

What's the maximum diagonal dimension of the floor plate, and what's the distance between the two stair doors?

Thank you for the information. A very good point I'll update that on my plans

 

[RLGA]

Here are my thoughts:

1. The stairways on the upper stories appear to be separated by no less than one-third of the overall diagonal; therefore, okay.
2. The diagonal hatching is a material symbol for masonry construction and does not necessarily mean it is rated. Walls without diagonal hatching means they are wood- or metal-framed walls. The extension for the stair on the left would require a 2-hour exit passageway to the exterior; however, a door is required at the stairway into the exit passageway because Exception 2 of Section 1023.3.1 would not apply since another door enters the exit passageway from the corridor.
3. The other stairway would be permitted to discharge into the corridor as shown per Exception 1 to Section 1028.2 for the following reasons:
   1. No more than 50% of the exits egress through the level of exit discharge (i.e., 1 out of 2 stairways = 50%).
   2. A free and unobstructed path to the exterior exit doors exists from the stairway.
   3. Since there is no basement, there is no need to separate the level of exit discharge with a fire-resistance rating equal to the stairway enclosure.
   4. The level of exit discharge is sprinklered throughout (required anyway because of the Group R occupancy).
   5. There are no exit access stairways to be concerned about separation distance on the level of exit discharge.
4. As for the OP's original question, I would classify the corridor as part of the Group R occupancy since it serves the residential upper stories. The restaurant cannot access this area; thus, it is not part of the Group A-2 occupancy. Commercial Space #2 (i.e., offices) has direct access to the exterior and does not require the corridor for access or egress. If the commercial space is partitioned into tenant areas that require the corridor for access, I would classify the corridor as part of the Group B occupancy, but the corridor would need to comply with the requirements of Group R occupancies if they are more restrictive than the Group B requirements.

 

[steveray]

So a minimum 0.5 hour assuming the sprinklers for R....But maybe 1 hour if they were separating uses R to B or R to A or B to A...I love when it is simple....