an exit doorway does not need fire separation

[sunyaer]

This is from Ontario Building Code Division B Part 9:
_____________________________________________________________________________________________________________________________
9.9.4.2. Fire Separation for Exits
(1) Except as provided in Sentence (5) and Article 9.9.8.5., every exit other than an exit doorway shall be separated
from each adjacent floor area or from another exit by a fire separation having a fire-resistance rating not less than that
required for the floor assembly above the floor area.

(2) Where there is no floor assembly above, the fire-resistance rating required in Sentence (1) shall not be less than that
required by Subsection 9.10.8. for the floor assembly below, but in no case shall the fire-resistance rating be less than
45 min.
_____________________________________________________________________________________________________________________________

Is an exit doorway a part of an exit? Would an exit doorway be connected to any adjacent floor area? ( I think there is no scenario where an exit doorway would be connected to any adjacent floor area, please confirm.)

 

[tmurray]

You are correct. Within this context, no.

We sometimes have what is called "horizontal exiting" which deals with passage from one side of a firewall to another, which means we are travelling from one building to another. I only bring this up because it looks like the situation you are describing, but it is highly dependent on the presence of the firewall and the code deals with this as a separate type of exit. In that situation, the doors would be fire rated to maintain the integrity of the firewall.

 

[sunyaer]

This is a floor layout with an exit:


* Floor Area *
* *
************* ===== ===== *
* *
* Exit *
* *
=== Exit doorway ==


Do the exit doorway and the exterior wall which contains this exit doorway ( === Exit doorway ==) require fire separation and fire resistance rating?

 

[tmurray]

I always find it helpful to think about the overall objective of the code when I am interpreting it.

When we fire rate an exit enclosure, it is to accomplish a couple goals:
1. prevent smoke and flame from entering into the exit enclosure from the building.
2. to prevent structural failure of the exit enclosure.

This assists us in two objectives in emergency response: reducing the chances of delays in egress from the building which could result in increased casualties, and to allow responding fire fighters to access the fire floor to reduce the chances of increased damage to the building.

In your example, the exit doorway does not really help with either goal, so it remains unregulated by the code.

There is another situation that could drive a fire rating: the proximity of the building to the lot line. If it is close enough, unprotected openings may not be permitted.

 

[sunyaer]

Sorry, the format in my last post got changed, and it's difficult to see what I was asking. Here are two layouts about exterior exit doorway, it would be greatly appreciated if you could answer the questions in the layouts.

Exterior exit doorway.pdf

Shared with Dropbox

www.dropbox.com

 

[sunyaer]

I always find it helpful to think about the overall objective of the code when I am interpreting it.

When we fire rate an exit enclosure, it is to accomplish a couple goals:
1. prevent smoke and flame from entering into the exit enclosure from the building.
2. to prevent structural failure of the exit enclosure.

.....

In your example, the exit doorway does not really help with either goal, so it remains unregulated by the code.

If the exit doorway is not a fire separation and not fire rated, is the exit enclosure really an true enclosure? It looks to me there is one side missing.

 

[tmurray]

OK. Some fundamentals before we get into this.

Means of Egress: It is a defined term, but functionally it is the path of travel for someone located somewhere within a building to a safe space. the safe space is usually outside in a public thoroughfare, but could be somewhere else (see definition). It includes both exits and access to exits.

Access to Exits: defined term, but it is the portion of the means of egress that leads from anywhere in a floor area to the exit.

Exit: defined term, portion of the means of egress that lead from the floor area to the safe space.

Fire separation: defined term, assembly that controls the passage of smoke and/or flame.

Fire resistance rating: Time in minutes or hours an assembly or material will withstand fire conditions.

Question 1: are these an exterior exit doorway: yes. They would be exempt from fire rating. In this situation, we would have an exit that is separated from the remainder of the building by a fire separation having a fire resistance rating. There is no need to rate the exterior doorway, as it does not separate any spaces inside the building.

Question 2: is this door considered an exit doorway: yes, same as above.

Question 3: does the exterior wall need a fire separation and/or fire resistance rating. It may been a fire resistance rating, but would not need to be a fire separation. We only need fire separations when we are separating spaces within the building. It may need a fire rating. If it is supporting a fire rated assembly (if the ceiling needs to be rated or floor above) a rating would be required for load bearing walls.

The second scenario would be rare to see. Usually the outside door would be the exit. Vestibules are rarely fire rated to provide the separation from the remainder of the floor area.

 

[sunyaer]

The second scenario would be rare to see. Usually the outside door would be the exit. Vestibules are rarely fire rated to provide the separation from the remainder of the floor area.

So, the "Exit" area shown on the second scenario usually would be a vestibule, correct?

 

[tmurray]

So, the "Exit" area shown on the second scenario usually would be a vestibule, correct?

Correct. Normally, the vestibule would be unrated, meaning nothing would need to be rated in that instance.