# Part 9, 2-storey Office Exiting requirements



## Sashcro (Aug 22, 2017)

I am designing a two storey, small office (60' x 48' each floor) that needs answers. The NBC & BCBC have me going in all sorts of directions. My goal, is to have one exit stair with fire separation, and one open stair (interconnected)(as per 3.2.8.2.6). However, there are also sections that tell me both required exits have to be enclosed and rated....while I am fairly certain that is the case, i am wondering if there is any sage advice out there that would direct me to something in the code that would allow this in a small 2-storey building.


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## RLGA (Aug 22, 2017)

I'm not familiar with Canadian building codes, but here in the states under the IBC, stairways between two adjacent stories are not required to be enclosed.


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## cda (Aug 22, 2017)

Well just welcome!!!

From south of the border


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## cda (Aug 22, 2017)

Look in the shaft section and see if it allows an opening between two stories.

Will look for how it is worded in the IBC 

Sprinkled building???


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## cda (Aug 22, 2017)

From IBC

Might look for similar wording 
Came fro fire and smoke protection chapter 

*712.1.9 Two-story openings.*
In other than Groups I-2 and I-3, a vertical opening that is not used as one of the applications listed in this section shall be permitted if the opening complies with all of the items below:


1.Does not connect more than two stories.


2.Does not penetrate a horizontal assembly that separates fire areas or smoke barriers that separate smoke compartments.


3.Is not concealed within the construction of a wall or a floor/ceiling assembly.


4.Is not open to a corridor in Group I and R occupancies.


5.Is not open to a corridor on nonsprinklered floors.


6.Is separated from floor openings and air transfer openings serving other floors by construction conforming to required shaft enclosures.


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## Sashcro (Aug 22, 2017)

cda said:


> Look in the shaft section and see if it allows an opening between two stories.
> 
> Will look for how it is worded in the IBC
> 
> Sprinkled building???


The building is not sprinklered. I sure wish i could use the IBC


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## ADAguy (Aug 22, 2017)

Welcome to our merry band. I believe as you wade through the waters of your code you will find the answer you seek.
Typically open stairs can achieve fire separation by use of smoke activated coiling or rolling fire doors. In the states we have allowed up to 3 interconnected stories with open stairwells using those doors.


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## cda (Aug 22, 2017)

Sashcro said:


> The building is not sprinklered. I sure wish i could use the IBC



See if there is similar wording

I do not think the north of the border codes are free to look at online or maybe our crack team would find it for you


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## tmurray (Aug 23, 2017)

Assuming 2015 NBC,

See Table 3.4.2.1.-A for single exit criteria for maximum travel distance and area. Based on the floor size you've provided, you should easily meet the requirements.

Now. The open stairwell. What 3.2.2 designation are you using? Assuming 3.2.2.62, you should meet the area restrictions by 3.2.8.2.(6)(b) for an unsprinklered interconnected floor space, provided the opening is just for the stairway.

What you are proposing appears acceptable.


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## Sashcro (Aug 23, 2017)

Thank you for your review. There is one 'complication'. There is a basement, used only for storage. The stair would be enclosed on the basement level however. This (3rd floor) is what leads me to think that i need 2 enclosed exits from upper floors. I am using 3.2.2.58 for this building, as it is a Group D occupancy, as well as the 2015 NBC.


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## Sashcro (Aug 23, 2017)

tmurray said:


> Assuming 2015 NBC,
> 
> See Table 3.4.2.1.-A for single exit criteria for maximum travel distance and area. Based on the floor size you've provided, you should easily meet the requirements.
> 
> ...


Table 3.4.2.1-A allows for a single exit if the floor area is under 200 SM, and if it is 2 floors or less. Unfortunately i am at 268 SM and 2 floors, plus a basement, so 3 floors


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## ADAguy (Aug 23, 2017)

You are the "designer", code minimums are your guide but may be subject to "exceptions". Are "exceptions" allowed in the NBC, is the basement sprinklered?
Is it enterable from the ground floor or could you eliminate the interconnection, leaving it only enterable from the exterior?


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## tmurray (Aug 23, 2017)

Sashcro said:


> Table 3.4.2.1-A allows for a single exit if the floor area is under 200 SM, and if it is 2 floors or less. Unfortunately i am at 268 SM and 2 floors, plus a basement, so 3 floors


Does the basement count as a storey? See the definition for first storey, storey and building height. Basically, if the basement is not the first storey it doesn't count in the application of 3.4.2.1.

Also see the definition of floor area because you deduct things like exits and shafts. You might be able to squeeze by.


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## tmurray (Aug 23, 2017)

ADAguy said:


> You are the "designer", code minimums are your guide but may be subject to "exceptions". Are "exceptions" allowed in the NBC, is the basement sprinklered?
> Is it enterable from the ground floor or could you eliminate the interconnection, leaving it only enterable from the exterior?


They are permitted through the application of an alternate solution. Basically the designer must prove that their design meets the minimum level of safety provided by a code provision based on the objective and functional statements attached to the code provision. It can be quite an involved process depending on the circumstances.


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## tmurray (Aug 23, 2017)

Wait, this is a Part 9 building correct? The single exit criteria is 9.9.8.2., still the same though.


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## Sashcro (Aug 23, 2017)

tmurray said:


> Does the basement count as a storey? See the definition for first storey, storey and building height. Basically, if the basement is not the first storey it doesn't count in the application of 3.4.2.1.
> 
> Also see the definition of floor area because you deduct things like exits and shafts. You might be able to squeeze by.


My first storey is the one above the basement. My deductions dont add up to much, as one of my exits is external to the building.


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## Sashcro (Aug 23, 2017)

tmurray said:


> Wait, this is a Part 9 building correct? The single exit criteria is 9.9.8.2., still the same though.


Yes. Part 9. Still the 2-exit requirement.


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## ADAguy (Aug 23, 2017)

we are trying to help, but .............?


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## Sashcro (Aug 23, 2017)

ADAguy said:


> You are the "designer", code minimums are your guide but may be subject to "exceptions". Are "exceptions" allowed in the NBC, is the basement sprinklered?
> Is it enterable from the ground floor or could you eliminate the interconnection, leaving it only enterable from the exterior?


Sorry ADAguy. Trying to get out a crazy deadline...i am sure you are familiar with such things  
The basement has an exterior exit, but the interior stairs and elevator are meant to be used to take things to store down there. So, they want interior access to basement.


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## Sashcro (Aug 23, 2017)

Sashcro said:


> Sorry ADAguy. Trying to get out a crazy deadline...i am sure you are familiar with such things
> The basement has an exterior exit, but the interior stairs and elevator are meant to be used to take things to store down there. So, they want interior access to basement.


The basement has a dry sprinkler for their archival storage, but sprinklers are not required by code.


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## tmurray (Aug 23, 2017)

Sashcro said:


> Yes. Part 9. Still the 2-exit requirement.


The only real way around it would be a timed egress study completed by a fire protection engineer. It may be easier/more cost effective to simply provide another exit. 

Alternatively, you could reduce the floor area on the second floor and provide a two storey atrium provided the wall on the second storey has an equivalent fire resistance rating as the floor. Other than that, I am out of ideas.


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## Sashcro (Aug 23, 2017)

Thanks for your help everyone. It is starting to look like i am going to have to tell the client that i have to either close off the internal stair, or add an additional one. Unfortunately, they are already trying to get too much into this floor plate and i cannot add any more size on this site.


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## tmurray (Aug 23, 2017)

They always try to push too much. Best of luck dealing with your client!


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## cda (Aug 23, 2017)

Sashcro said:


> Thanks for your help everyone. It is starting to look like i am going to have to tell the client that i have to either close off the internal stair, or add an additional one. Unfortunately, they are already trying to get too much into this floor plate and i cannot add any more size on this site.





So do you have a shaft section in the code

And no allowance for two floors open??

Do you know what the NBC code is based on?? IBC or 101 or Canada only?


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## Sashcro (Aug 23, 2017)

NBC (National Building Code) is a whole new animal, Canada only. There are very brief comments on shafts. but not a shaft 'section'. I can not find any allowance for two open floors, only that i need 2 exits and they both need to be rated. There are some areas that suggest i can have an opening (interconnected space) but lots of complications unfortunately. So, 3 sets of stairs for a small building like this one is not going to fly.


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## ADAguy (Aug 23, 2017)

Maybe if you place the elevator on an outside wall with 2 doors, one opening to the building and the other opening to the basement. Same with the stairs, basement exits to exterior only with no interconnect to building.


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## cda (Aug 23, 2017)

Sashcro said:


> NBC (National Building Code) is a whole new animal, Canada only. There are very brief comments on shafts. but not a shaft 'section'. I can not find any allowance for two open floors, only that i need 2 exits and they both need to be rated. There are some areas that suggest i can have an opening (interconnected space) but lots of complications unfortunately. So, 3 sets of stairs for a small building like this one is not going to fly.




So is there a section in there covering when shafts have to be rated?


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## tmurray (Aug 24, 2017)

cda said:


> So is there a section in there covering when shafts have to be rated?


We don't have "shafts" we have exit enclosures and vertical service spaces.



ADAguy said:


> Maybe if you place the elevator on an outside wall with 2 doors, one opening to the building and the other opening to the basement. Same with the stairs, basement exits to exterior only with no interconnect to building.


The basement is not the issue. The floor area is what is requiring two exits in this case. In the NBC only storeys between the first storey and the highest storey count in determining building height. The first storey is defined as the lowest storey not have a finished floor elevation of more than 2 meters above grade. So in this scenario, the building is considered to have two storeys. 9.9.8.2.(2)


In the NBC, the floor area is the area on the storey while subtracting exit enclosures and vertical service spaces.


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## tmurray (Aug 24, 2017)

cda said:


> So do you have a shaft section in the code
> 
> And no allowance for two floors open??
> 
> Do you know what the NBC code is based on?? IBC or 101 or Canada only?



Two open floors would generally be considered an interconnected floor space and only permitted in a fully sprinklered building, There is a possibility for both open and closed mezzanines without sprinkler protection, but they would be restricted to 40% and 10% of the floor area respectively. 

The NBC is developed by the Canadian Commission on Building and Fire Codes under the guidance of the National Research Center. There are times when NFPA 101 can be substituted, like in developing occupant loads, as this code is much closer to how ours is developed. IBC is completely out in left field for us, there are sections that are very similar, but other that are completely different.


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## steveray (Aug 24, 2017)

Is sprinklering the building feasible? How much more than second exit? The sprinklers may have a "payback" in lower insurance and future design flexibility....


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## Sashcro (Aug 24, 2017)

steveray said:


> Is sprinklering the building feasible? How much more than second exit? The sprinklers may have a "payback" in lower insurance and future design flexibility....


Client is already over budget. If i were to spring that on them, they are likely to pull the plug. I am going to have to keep that in mind next time though. Regardless if sprinklers are required or not, sometimes they can be suggested in the early stages to avoid some of these issues later on.


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