Open stair as means of egress?

[gnarkill283]

We have to add 1 or even 2 stairs because of the ridiculous requirement that a large deck area of a 3rd floor office has to count as an assembly occupancy. We can provide stairs at the corners of the deck. Can these be open stairs all the way through the building, or open at the 3rd floor and enclosed through the rest of the building, or open at the 3rd floor and enclosed on the interior side of the building but exposed on the exterior, or enclosed entirely? The plan is basically a smaller office space rectangle surrounded by a larger open air deck rectangle with the additional stairs at far corners.

 

[cda]

Anyone have an answer?

 

[bill1952]

Without drawings, it's very hard to grasp the issues, and I don't even know what or which questions to ask to start. I'd rather solve the "ridiculous requirement" question than advise or speculate on what kind of stairs to solve it. Or will they have parties with hundreds of people?

Apologies but I just have trouble solving design problems without seeing the whole problem.

 

[Joe.B]

I agree with Bill. Very little information provided and a potentially confrontational attitude to go with it, hard to tell through text alone. There is obviously some frustration. "Large Deck Area" in my mind could mean "lots of people" so a requirement for more egress doesn't seem ridiculous to me. Life safety is not a priority to some people, only making money. But that's very presumptuous on my part, I don't know if this person is the owner, designer, accountant, dog walker... Maybe with more information I could see why they don't like it, but as is I'm out.

 

[bill1952]

I guess with what I'll call so much anti-social behavior among our elected federal and state leaders (?) I like giving people the benefit of the doubt. Plus, too often someone will ask me about a code issue in my narrow speciality (assembly) and when I see the drawing, it's "Oh! That's what you were trying to describe in words." Maybe it is a lunch time deck for 50 employees, but sure as shooting someone will want their daughter's wedding reception there and the next thing you know lots of people do.

And I can't resist an interesting and possibly unique code challenge.

 

[gnarkill283]

Due to confidentiality I can't share plans but here is a link to a very crude drawing of the condition: https://ibb.co/HP7PGx7 I'm an architect and this core and shell office floor may include 1 tenant or as many as 4. Our original argument was that the entire floor is only accessed through keycards by the employees of the floor and therefore the deck has no additional occupancy. They didn't buy that (neither did we really) but the deck is so large that if we count it as assembly (15sf per occ) it adds 750 more people when there's only 130 business occupants currently. We are able to provide 2 additional stairs at 5'9" and 5'6" wide (both won't require an intermediate handrail because 2 handrails are within 30" reach if the railings project 4.5" on each side - hence 5'9 being max stair before you need the 3rd handrail). This gives us 504 occupants due to the formula of FFPC 7.3.3.2. We will make planters to reduce the area to accommodate 504 occupants which will all exit through these 2 new stairs rather than through the building which would require in-swinging doors not good for hurricanes. The stairs are near lot lines and pass through a 2nd floor parking garage and ground floor retail. My questions remain the same as in the original post - can the stairs be open, etc?

 

[gnarkill283]

From my research, I found you can have open stairs as long as you meet FBC 1027.3 and NFPA 7.2.2.6.3.1 which states "Outside stairs serving an exterior exit access balcony that has two remote outside stairways or ramps shall be permitted to be unprotected." But our life safety consultant and my boss quickly dismiss these exceptions because of smoke and that the stairs are at the lot line (they didn't give any further explanation or code reference) and they must be enclosed and fire rated but can be open on the 3rd floor only. Are they right?

 

[cda]

Did you ask for a reduced occupant load??

Have to find the section

 

[bill1952]

Thank you. Makes much more sense. I'd be inclined to think they could be open like a stadium or grandstand but defer to others for this one.

 

[cda]

From my research, I found you can have open stairs as long as you meet FBC 1027.3 and NFPA 7.2.2.6.3.1 which states "Outside stairs serving an exterior exit access balcony that has two remote outside stairways or ramps shall be permitted to be unprotected." But our life safety consultant and my boss quickly dismiss these exceptions because of smoke and that the stairs are at the lot line (they didn't give any further explanation or code reference) and they must be enclosed and fire rated but can be open on the 3rd floor only. Are they right?

Exception: Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than those determined by calculation, shall be permitted to be used in the determination of the design occupant load.

 

[gnarkill283]

Exception: Where approved by the building official, the actual number of occupants for whom each occupied space, floor or building is designed, although less than those determined by calculation, shall be permitted to be used in the determination of the design occupant load.

We have spoken to the building official and it needs to be 15sf per occ on the deck. The main question is the enclosure of the stairs

 

[mtlogcabin]

2018 IBC
1027.5 Location.
Exterior exit stairways and ramps shall have a minimum fire separation distance of 10 feet (3048 mm) measured at right angles from the exterior edge of the stairway or ramps, including landings, to:

1. Adjacent lot lines.

2. Other portions of the building.

3. Other buildings on the same lot unless the adjacent building exterior walls and openings are protected in accordance with Section 705 based on fire separation distance.

For the purposes of this section, other portions of the building shall be treated as separate buildings.

Exception: Exterior exit stairways and ramps serving individual dwelling units of Group R-3 shall have a minimum fire separation distance of 5 feet (1525 mm).

 

[gnarkill283]

2018 IBC
1027.5 Location.
Exterior exit stairways and ramps shall have a minimum fire separation distance of 10 feet (3048 mm) measured at right angles from the exterior edge of the stairway or ramps, including landings, to:

1. Adjacent lot lines.

2. Other portions of the building.

3. Other buildings on the same lot unless the adjacent building exterior walls and openings are protected in accordance with Section 705 based on fire separation distance.

For the purposes of this section, other portions of the building shall be treated as separate buildings.

Exception: Exterior exit stairways and ramps serving individual dwelling units of Group R-3 shall have a minimum fire separation distance of 5 feet (1525 mm).

This means enclosed (interior) stairs are ok if within 10' of lot line right? This also means it can't be open on the 3rd floor if within 10'?