Partial Change of Occupancy Classification and Sprinkler Requirements in existing non-conforming buildings.

[fungineer]

Code 2015 IEBC w/ Wisconsin Amendments (SPS 366).

Existing condition:
An existing, unsprinklered, (single) building of 30,000 sq. ft. is has mixed unseparated S-1 & B occupancies. This is a single tenant with an occupancy certificate for both uses. This has been considered a "legally existing non-conforming" for the amount of S-1 compared to the current IBC code. My understanding is that it was legally built under permit previously into this condition. Approximately 9,000 sq. ft. of the building is used similar to B (offices) and the remainder as combustible storage/warehousing.

Proposed work:

Alter the layout to create offices and rearrange the space, including changing approximately 5,000 sq. ft. of S-1 space into B use.
Although the S-1 and B spaces are non-separated currently, the actual use of the space has changed so it dose still appear to be a partial change-in-occupancy classification. IEBC 2015 1001.2.2 states that 1012 would apply.

Additionally, the following other changes will occur:

(2) fire barriers will be constructed creating (3) separated occupancies each approximately 10,000 sq. ft. within the building: (2) Mixed S-1/B and (1) S-1 only. This fire barriers are 2-hour rated, which meets IBC 508.4, but they are not 3-hour which would be required for IBC 707.3.10, thus it would remain a single fire area of 20,000 sq. ft.

Specific items for discussion:

IEBC 1012.2.1 states: "Where a change in occupancy classification occurs......that requires an automatic fire sprinkler system to be provided based on the new occupancy in accordance with Chapter 9 of the IBC, such system shall be provided throughout the area where the occupancy occurs" (See snippet for unapplicable portion).

However, IEBC 1012.2.



In the proposed situation, the separated occupancies (10,000 sq. ft.) would still be mixed-use B/S-1.
As such, the questions area these:

1) Within the (2) 10,000 sq. ft. separated areas, which include a Change of Use from S-1 to B., are sprinklers required?
Related Discussion Items:
a) [No sprinklers are required for the B offices themselves per IBC 903.
b) Due to the existing S-1, the change of use still occurs within a fire area where sprinklers would be required by IBC 903.2.9 (1).
c) Is it correct to read the verbiage of 1012.2.1 in combination with 1012.1.1.1 require the sprinklers?
d) Alternatively, is the general (IEBC 702.1) provision to make the building "no less safe" applicable here whereas the change from S-1 to B has actually made the building safer, or at least no less safe". (I would assume no because this is a change in use, not just an alteration, so additional requirements apply as noted above).

2) Per the verbiage in the commentary for 1012.1.1.2, it talks about providing occupancy separations per 508.4 to limit the extent of change-in-use requirements, including "...this shall also relate to exceeding the fire area..."
a) My understanding is that this would mean that sprinklers (if required in 1) would only be required in the (2) separated areas, but not the 3rd unchanged S-1 area. Do others agree?

 

[mtlogcabin]

As the designer YOU get to pick which method to use

SECTION 506
CHANGE OF OCCUPANCY

506.1 Compliance.
A change of occupancy shall not be made in any building unless that building is made to comply with the requirements of the International Building Code for the use or occupancy. Changes of occupancy in a building or portion thereof shall be such that the existing building is not less complying with the provisions of this code than the existing building or structure was prior to the change. Subject to the approval of the building official, changes of occupancy shall be permitted without complying with all of the requirements of this code for the new occupancy, provided that the new occupancy is less hazardous, based on life and fire risk, than the existing occupancy.

 

[Yankee Chronicler]

What's the type of construction, and what code was the building constructed under? 30,000 square feet exceeds the allowable area for an unsprinklered building of either B or S-1 if it's construction type II-B.

My understanding of the IEBC for adding sprinklers (from memory) is that you only have to add sprinklers if a new occupancy is a higher hazard than the old occupancy. S-1 and B are equal hazard, so I don't think there's anything you have described that would trigger a requirement to retrofit with sprinklers.

If the building can legally be non-separated B and S-1 at 30,000 square feet, what's the purpose of creating a fire barrier to break it into two fire areas? Is it just to call it two fire areas? To your specific questions:

1) Irrelevant. You can't sprinkler part of a building. You can install limited area sprinklers to protect specific, individual hazards, but a building is either sprinklered or non-sprinklered. A building that has sprinkler protection in half of the building area is an unsprinklered building.

1)d) B and S-1 are equal fire hazard.

2)a) See above. You don't sprinkler part of a building. Sprinklering part of a building doesn't get you anything nder the code.

 

[fungineer]

For @Yankee Chronicler, 30,000 is actually a rounded number to make the math easier, as my focus is not on the type of construction. Note that the height and area (chapter 5 IBC) provisions IEBC don't apply per IEBC to equal or lower hazards, such as this case). It was through a historic Wisconsin code, in which B,M,F were all together (and S didn't explicitly exist). It looks like it was most likely "Mill construction" at the time, which, though this can very, is most similar to IV (HT) under the 2015 code. Under the 1956 code this appears to be built under, 30,000 sq. ft. was allowed with 3 street frontages. Please put that aside for the sake of the other questions though.

1) Partial sprinklers are indeed an option, as the section 1012.1.1.2 specifically states that the changes only need to be applied within the separated occupancy undergoing a change in use, not the whole building, (unless otherwise required by another part of the code.)

For @mtlogcabin, what code are you reviewing that from? I'm looking at the IEBC 2015 and the (work area) 506 section is much, much less user friendly/lenient then the method you indicate. (As far as method, note too that this will be looked at under a work area method and Chapter 10, as Chapter 4 (prescriptive) isn't adopted in WI and performance isn't being selected due to other reasons.)



Thus I end up back at 1c) Is it correct to read the verbiage of 1012.2.1 in combination with 1012.1.1.1 require the sprinklers (IEBC 2015), or should only the "B" be looked at in this situation, ignoring all the existing use to remain/within same fire area?

 

[mtlogcabin]

2018 IEBC is what I posted. I see that was chapter 4 in the 2015 edition.

By changing a portion of the S-1 to a B occupancy you are reducing the fire loading in the building

or should only the "B" be looked at in this situation, ignoring all the existing use to remain/within same fire area?

That is how I would look at it.