Group R separation from adjacent occupancy

[Sifu]

2018 IBC, VB, mixed-use R3, B, M, S-1, non-sep., NFPA 13.

420.2 drives us to 708 for the required separation of dwelling units, sleeping units and from either of those from other occupancies in the same building. Base rating for a fire partition is 1-hr. 708.3 exc. #2 allows a reduction in the rating from 1-hr to 1/2-hr for dwelling and sleeping unit separations. I read this to mean the reduction is allowed between from dwelling and sleeping units to dwelling and sleeping units, but not from either one to an adjacent occupancy that is not a dwelling unit or sleeping unit. Am I reading this wrong?

 

[Joe.B]

I don't think you're reading it wrong. Definitely watching this one though to see what others think.

 

[steveray]

If there is a higher rating, that would apply…but that would sort of only apply in separated occupancies…? Let’s say you had a leasing office adjacent to a unit in an apartment building, 30 minutes would be fine…

 

[Yankee Chronicler]

2018 IBC, VB, mixed-use R3, B, M, S-1, non-sep., NFPA 13.

420.2 drives us to 708 for the required separation of dwelling units, sleeping units and from either of those from other occupancies in the same building. Base rating for a fire partition is 1-hr. 708.3 exc. #2 allows a reduction in the rating from 1-hr to 1/2-hr for dwelling and sleeping unit separations. I read this to mean the reduction is allowed between from dwelling and sleeping units to dwelling and sleeping units, but not from either one to an adjacent occupancy that is not a dwelling unit or sleeping unit. Am I reading this wrong?

You are reading it correctly as far as you're reading it, but neither 420.2 nor 708 in any way addresses separation between R occupancies and other occupancies in the same building. But you said the building is NON-separated mixed uses. In that case, there is no separation required between any of the different use groups in the building, but the height and area of the building will then be limited to the most restrictive requirements of any of the included occupancies.

 

[steveray]

In that case, there is no separation required between any of the different use groups in the building, but the height and area of the building will then be limited to the most restrictive requirements of any of the included occupancies.

Which can be a sprinkler issue if they want to use 13R and one of the other uses would drive a 13 system…OP says 13 so not an issue here…

 

[Joe.B]

 

[steveray]

View attachment 17182

Correct…which will circle you back round to 30 minutes..unless it is also a separated occupancy and then 508.4 prevails or a separate fire area then you are looking at 707.3.10ish. Simple…

 

[Sifu]

You are reading it correctly as far as you're reading it, but neither 420.2 nor 708 in any way addresses separation between R occupancies and other occupancies in the same building. But you said the building is NON-separated mixed uses. In that case, there is no separation required between any of the different use groups in the building, but the height and area of the building will then be limited to the most restrictive requirements of any of the included occupancies.

View attachment 17181

Not sure I agree. I have always believed 420 is absolute, no matter whether it is separated or non-separated.
commentary:
Even where those other areas are regulated under the accessory occupancies
or nonseparated occupancies option of mixed
occupancies contained in Sections 508.2 or 508.3
respectively, these partitions and horizontal assemblies
are still required.

And 420 does expressly address separating DU's and SU's from other occupancies contiguous to them in the same building.

420.2 Separation walls. Walls separating dwelling units in
the same building, walls separating sleeping units in the same
building and walls separating dwelling or sleeping units from
other occupancies contiguous to them in the same building
shall be constructed as fire partitions in accordance with Section
708.

My question is whether the reduction from the min. per 708 is supposed to include this part:
walls separating dwelling or sleeping units from
other occupancies contiguous to them in the same building

If a sprinklered (13) non-separated mixed use occupancy building has a B and two DU's:
-they need at least a 1/2-hr FP between the DU's, but no separation between the B and DU
or
-All must be separated by min. 1/2-hr.

So to answer, even though I don't think the code as written clearly gets me there: and I would note that the code language referenced in the interp have changed, not sure how that affects the validity of the interp, but in essence I thing the question was answered, at least 20 years ago.

Here is why this comes up:
I have a mixed use, B,S,M building, VB, non-sep, sprinklered (13) existing building. There is a central suite (2 story) and a side suite on each end (one is two-story) and the other is one story. Original core-shell docs were for a complete B,S1 space (the center space), with future B or M on either side. Now they propose to make the 2-story space an R3. They call it a caretaker suite...(it is not a live/work) They provide a 1-hr FP between the R3 and the rest of the building (I did not ask for it, they just did it, and it wasn't on the core-shell). Part of the R dwelling unit has a large rooftop balcony, which previously shared a wall with large storefronts and openings with the center occupancy. Now, if they are required to rate it (and even if they aren't but they show it as a rated wall assembly, they must deal with the glazing and opening. If the wall is not required to be rated, but they call the wall rated? If it is required to be rated, as 1-hr (no reduction) it must be 3/4-hr, or as 1/2 hour (reduction applied) it only has to be 1/3-hr.

I think the interp helps, but only in regards to what is required, not what is provided.

 

[steveray]

Not sure I agree. I have always believed 420 is absolute, no matter whether it is separated or non-separated.
commentary:
Even where those other areas are regulated under the accessory occupancies
or nonseparated occupancies option of mixed
occupancies contained in Sections 508.2 or 508.3
respectively, these partitions and horizontal assemblies
are still required.

And 420 does expressly address separating DU's and SU's from other occupancies contiguous to them in the same building.

420.2 Separation walls. Walls separating dwelling units in
the same building, walls separating sleeping units in the same
building and walls separating dwelling or sleeping units from
other occupancies contiguous to them in the same building
shall be constructed as fire partitions in accordance with Section
708.

My question is whether the reduction from the min. per 708 is supposed to include this part:
walls separating dwelling or sleeping units from
other occupancies contiguous to them in the same building

If a sprinklered (13) non-separated mixed use occupancy building has a B and two DU's:
-they need at least a 1/2-hr FP between the DU's, but no separation between the B and DU
or
-All must be separated by min. 1/2-hr.

So to answer, even though I don't think the code as written clearly gets me there: and I would note that the code language referenced in the interp have changed, not sure how that affects the validity of the interp, but in essence I thing the question was answered, at least 20 years ago.
View attachment 17185
Here is why this comes up:
I have a mixed use, B,S,M building, VB, non-sep, sprinklered (13) existing building. There is a central suite (2 story) and a side suite on each end (one is two-story) and the other is one story. Original core-shell docs were for a complete B,S1 space (the center space), with future B or M on either side. Now they propose to make the 2-story space an R3. They call it a caretaker suite...(it is not a live/work) They provide a 1-hr FP between the R3 and the rest of the building (I did not ask for it, they just did it, and it wasn't on the core-shell). Part of the R dwelling unit has a large rooftop balcony, which previously shared a wall with large storefronts and openings with the center occupancy. Now, if they are required to rate it (and even if they aren't but they show it as a rated wall assembly, they must deal with the glazing and opening. If the wall is not required to be rated, but they call the wall rated? If it is required to be rated, as 1-hr (no reduction) it must be 3/4-hr, or as 1/2 hour (reduction applied) it only has to be 1/3-hr.

I think the interp helps, but only in regards to what is required, not what is provided.

Yes…420 always has a separation…I think we are all agreeing. Just a question of 30 minutes Or more….an easier way to label it out is fire partition or fire barrier and that visual really clarifies it…