Single Exits in R-2 Dwelling Units

[gtyler75]

Referencing 2015 Michigan Building Code in relation to an R-2 building

Trying to maximize the possibilities of a single-exit R-2 building. So looking at Section 1006 Number of Exits

In particular, I'm looking at the single exit exceptions (1006.3.2)- if any of the conditions apply, a story is allowed a single exit. I see one small, but potentially consequential, discrepancy within these exceptions.

1006.3.2 Condition 1 references a table specific to R-2 occupancies that allows a single exit for basement, first, second, and third floors (max 4 dwelling units per floor, 125 ft common path of egress travel). It also says 4th or higher story dwelling units are not permitted with a single exit.

1006.3.2 Condition 2, however, does not have the upper story caveat. Instead, it says that an R-2 space/area (dwelling unit) with a max occupancy load of 10 and common egress travel distance of 125 ft is allowed a single exit.

It seems very possible to have dwelling units on the fourth, or maybe higher floors, that would meet Condition 2, but would obviously conflict with Condition 1. I know they are technically not co-dependent, but I'm just wondering if anyone has tried this, or guidance on whether I'd run into issues later on.

Many thanks

 

[RLGA]

Condition 2 requires egress directly at the level of exit discharge, which means at or close to grade. It would be nearly impossible to have each story in a multi-story building to discharge directly at or near grade unless you have some serious site slope.

 

[gtyler75]

Condition 2 requires egress directly at the level of exit discharge, which means at or close to grade. It would be nearly impossible to have each story in a multi-story building to discharge directly at or near grade unless you have some serious site slope.

If an exit stair opened directly to the unit from the landing area, as in a point-access apartment building, it seems like this would be plausible scenario

 

[RLGA]

If an exit stair opened directly to the unit from the landing area, as in a point-access apartment building, it seems like this would be plausible scenario

Do you mean a single apartment on the fourth story with a single exit stair that goes down to grade would comply?

 

[gtyler75]

Do you mean a single apartment on the fourth story with a single exit stair that goes down to grade would comply?

Yes, or I suppose more than one apartment, assuming they each egress directly to the exit stair/shaft. In other words, because an entire exit stair (the whole shaft) is an exit and would directly egress at the level of exit discharge, it would be possible to have units on upper floors meet condition 2.

 

[RLGA]

Yes, or I suppose more than one apartment, assuming they each egress directly to the exit stair/shaft. In other words, because an entire exit stair (the whole shaft) is an exit and would directly egress at the level of exit discharge, it would be possible to have units on upper floors meet condition 2.

The keyword in Condition #2 is "directly." The exit is not directly to the level of exit discharge--you have to go down several flights of stairs until you reach the level of exit discharge. Remember, the exterior stair is an exit, so the exit discharge starts where the exit ends, which would be at the bottom of the stairs. Thus, when someone enters the exit, they do not have direct access to the exit discharge.

More fundamentally, you will note that Condition #2 states that it applies to "rooms, areas, and spaces"--it does not mention stories.

 

[gtyler75]

I'm not sure I agree. Once you step into the shaft of an exit stair, regardless of the floor, you are in an exit. The whole shaft is the exit, not just the door to the exterior, therefore the space would discharge directly to the exterior, regardless of where you enter the stair. I don't see why this definition would be applied differently only in the context of condition #2.

As for the area vs. story question, table 1006.2.1 could apply to any room/area/space on any story, so long as it meets the travel distance requirement. The story is irrelevant. 1006.2 "Rooms, areas or spaces, including mezzanines, within a story or basement shall be provided with the number of exits or access to exits in accordance with this section."

I appreciate your responses!

 

[steveray]

While the language probably could be clearer, Ron is correct with intent and that is sort of the difference #2 and #4 and why that language is different...

 

[gtyler75]

Well, I had to try haha.

Is there an official code commentary that confirms this intention? I need to appease my boss

Thanks for the responses

 

[my250r11]

Commentary on item 2 is in RED:


1006.3.2 Single exits. A single exit or access to a single exit
shall be permitted from any story or occupied roof where one
of the following conditions exists:
1. The occupant load, number of dwelling units and exit
access travel distance do not exceed the values in Table
1006.3.2(1) or 1006.3.2(2).
2. Rooms, areas and spaces complying with Section
1006.2.1 with exits that discharge directly to the exterior
at the level of exit discharge, are permitted to have
one exit or access to a single exit.
3. Parking garages where vehicles are mechanically
parked shall be permitted to have one exit or access to a
single exit.
4. Group R-3 and R-4 occupancies shall be permitted to
have one exit or access to a single exit.
5. Individual single-story or multistory dwelling units
shall be permitted to have a single exit or access to a
single exit from the dwelling unit provided that both of
the following criteria are met:
5.1. The dwelling unit complies with Section
1006.2.1 as a space with one means of
egress.
5.2. Either the exit from the dwelling unit discharges
directly to the exterior at the level of
exit discharge, or the exit access outside the
dwelling unit’s entrance door provides access
to not less than two approved independent
exits.
The base assumption is that all stories of a building
shall have access to at least two separate ways out
for emergencies.
Single-exit stories can have access to an exit from
any floor, therefore, single-exit stories can use an
open exit access stairway for as many stories as permitted
by Sections 1006.3.2 and 1019.3.3 provided
they meet the exit access of travel distance limitations
for that use in Sections 1006.2.1 and 1006.3.2
and Tables 1006.2.1, 1006.3.2(1) and 1006.3.2(2).
A story can have a single exit if the design meets
one of the five items listed.
Item 1 states what situations permit one exit by a
reference to Tables 1006.3.2(1) and 1006.3.2(2). If a
story can meet the provisions for occupant load, number
of units and travel distance in Table 1006.3.2(1)
or 1006.3.2(2), then that story can have one means
of egress. See the commentary for Tables
1006.3.2(1) and 1006.3.2(2) for information on singleexit
buildings.
Item 2 references Table 1006.2.1 for single-exit
spaces. Table 1006.2.1 is intended to be applicable
to rooms and spaces on a floor, but not to an entire
floor level. One of the main concerns has been that
vertical travel takes longer than horizontal travel in
emergency exiting situations. However, if the singleexit
space can exit directly to the exterior rather than
egress into an interior corridor, a higher level of
safety is provided. While the term “building” limits the
area addressed to that bordered by exterior walls or
fire walls, a common application of Item 2 is on a tenant-
by-tenant basis. For example, a single-story strip
mall may not meet the provisions for a building with
one means of egress but each tenant area meets the
provisions for a space with one means of egress in
accordance with Section 1006.1. This tenant could
exist as either a stand-alone single-exit building or as
a single-exit tenant space that exits into an interior
corridor. Is it not just as safe to permit this tenant to
exist as part of a larger building with the door exiting
directly to the exterior? See also the commentary to
Tables 1006.3.2(1) and 1006.3.2(2).
While not specifically stated in this section, there is
a situation where the single means of egress can be
used from a multilevel tenant space. When the combined
occupant load of the space and a mezzanine
meets the occupant load in Table 1006.2.1 and the
common path of travel distance measured from the
most remote point down the exit access stairway and
to the exterior exit doorway, the ground floor space
and its mezzanine can be considered a space with
one means of egress.

 

[gtyler75]

Commentary on item 2 is in RED:


1006.3.2 Single exits. A single exit or access to a single exit
shall be permitted from any story or occupied roof where one
of the following conditions exists:
1. The occupant load, number of dwelling units and exit
access travel distance do not exceed the values in Table
1006.3.2(1) or 1006.3.2(2).
2. Rooms, areas and spaces complying with Section
1006.2.1 with exits that discharge directly to the exterior
at the level of exit discharge, are permitted to have
one exit or access to a single exit.
3. Parking garages where vehicles are mechanically
parked shall be permitted to have one exit or access to a
single exit.
4. Group R-3 and R-4 occupancies shall be permitted to
have one exit or access to a single exit.
5. Individual single-story or multistory dwelling units
shall be permitted to have a single exit or access to a
single exit from the dwelling unit provided that both of
the following criteria are met:
5.1. The dwelling unit complies with Section
1006.2.1 as a space with one means of
egress.
5.2. Either the exit from the dwelling unit discharges
directly to the exterior at the level of
exit discharge, or the exit access outside the
dwelling unit’s entrance door provides access
to not less than two approved independent
exits.
The base assumption is that all stories of a building
shall have access to at least two separate ways out
for emergencies.
Single-exit stories can have access to an exit from
any floor, therefore, single-exit stories can use an
open exit access stairway for as many stories as permitted
by Sections 1006.3.2 and 1019.3.3 provided
they meet the exit access of travel distance limitations
for that use in Sections 1006.2.1 and 1006.3.2
and Tables 1006.2.1, 1006.3.2(1) and 1006.3.2(2).
A story can have a single exit if the design meets
one of the five items listed.
Item 1 states what situations permit one exit by a
reference to Tables 1006.3.2(1) and 1006.3.2(2). If a
story can meet the provisions for occupant load, number
of units and travel distance in Table 1006.3.2(1)
or 1006.3.2(2), then that story can have one means
of egress. See the commentary for Tables
1006.3.2(1) and 1006.3.2(2) for information on singleexit
buildings.
Item 2 references Table 1006.2.1 for single-exit
spaces. Table 1006.2.1 is intended to be applicable
to rooms and spaces on a floor, but not to an entire
floor level. One of the main concerns has been that
vertical travel takes longer than horizontal travel in
emergency exiting situations. However, if the singleexit
space can exit directly to the exterior rather than
egress into an interior corridor, a higher level of
safety is provided. While the term “building” limits the
area addressed to that bordered by exterior walls or
fire walls, a common application of Item 2 is on a tenant-
by-tenant basis. For example, a single-story strip
mall may not meet the provisions for a building with
one means of egress but each tenant area meets the
provisions for a space with one means of egress in
accordance with Section 1006.1. This tenant could
exist as either a stand-alone single-exit building or as
a single-exit tenant space that exits into an interior
corridor. Is it not just as safe to permit this tenant to
exist as part of a larger building with the door exiting
directly to the exterior? See also the commentary to
Tables 1006.3.2(1) and 1006.3.2(2).
While not specifically stated in this section, there is
a situation where the single means of egress can be
used from a multilevel tenant space. When the combined
occupant load of the space and a mezzanine
meets the occupant load in Table 1006.2.1 and the
common path of travel distance measured from the
most remote point down the exit access stairway and
to the exterior exit doorway, the ground floor space
and its mezzanine can be considered a space with
one means of egress.

Thanks!

 

[Ted Smith]

Hi I have a 4 story townhome with 3 units up for permit review. The top two stories are one unit that egress on the 3rd floor. We thought we could use exception 5 since the unit exits directly to exit enclosure which exits directly outside. We got a comment back from the reviewer that this condition doesn’t meet this exception. We have done this same configuration under the 2009 inch, but the 2018 verbage has changed. Does anyone have any recommendations how to accommodate this scenario with one exit?

 

[Jay Smith]

Hi I have a 4 story townhome with 3 units up for permit review. The top two stories are one unit that egress on the 3rd floor. We thought we could use exception 5 since the unit exits directly to exit enclosure which exits directly outside. We got a comment back from the reviewer that this condition doesn’t meet this exception. We have done this same configuration under the 2009 inch, but the 2018 verbage has changed. Does anyone have any recommendations how to accommodate this scenario with one exit?

In Item 5 when the occupants exit the unit itself, they must be at grade. The exit access stair would have to be within the unit.

 

[Ted Smith]

In Item 5 when the occupants exit the unit itself, they must be at grade. The exit access stair would have to be within the unit.

Thanks Jay, do you know of any way to adapt our exit strategy to become code applicable with one exit stair still?

 

[Jay Smith]

Thanks Jay, do you know of any way to adapt our exit strategy to become code applicable with one exit stair still?

The only thing I can think of besides two means of egress from the 3rd story is reducing the 4th story to a mezzanine.