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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Part 9, 2-storey Office Exiting requirements
- Thread starter Sashcro
- Start date
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.
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:
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.
ADAguy
REGISTERED
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.
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.
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
tmurray
SAWHORSE
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.
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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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.
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
ADAguy
REGISTERED
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?
Is it enterable from the ground floor or could you eliminate the interconnection, leaving it only enterable from the exterior?
tmurray
SAWHORSE
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.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
Also see the definition of floor area because you deduct things like exits and shafts. You might be able to squeeze by.
tmurray
SAWHORSE
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.
tmurray
SAWHORSE
Wait, this is a Part 9 building correct? The single exit criteria is 9.9.8.2., still the same though.
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.
Yes. Part 9. Still the 2-exit requirement.
ADAguy
REGISTERED
we are trying to help, but .............?
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.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.
tmurray
SAWHORSE
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.
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.
tmurray
SAWHORSE
They always try to push too much. Best of luck dealing with your client!
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?