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Chapter 34 Existing Buildings Question - Complex Addition to Multiple Exist Bldgs.

E

ETThompson

SAWHORSE
Joined
May 19, 2017
Messages
190
Location
Columbus, Ohio
We are building an addition to an existing complex of buildings. Our addition will connect two existing structures (ie, our addition is between the two existing buildings, and when complete we will have one continuous building). See attached plan and section sketch.

The existing north building we be renovated and will have an A-1 auditorium, and B Dance Studios and S-2 storage areas. The existing south building has primarily offices, dance studios (all B) and S-2 storage. The new “connector” addition is A-3.

The existing south building is not sprinkelered and it would be prohibitively expensive to sprinkeler. The north building and addition we intend to sprinkeler.

We are looking into whether a Chapter 34 existing buildings analysis will help us (seems like it would). We are under the Ohio Building Code 2017 < http://codes.ohio.gov/oac/4101:1 > which is based on the 2015 IBC, but Ohio has *not* adopted the IEBC (though I suppose if it helps us we could make that argument).

So, I’m running the evaluation as described in Section 3412, and have a few questions:
  • For “Additions” in 3412.2.3.2 it says we can use a Fire Barrier between the addition and the new construction as long as we meet the conditions listed. We think this is a viable path, does that make sense?
  • One of the existing buildings (south building) is clearly older than 1979 (the Ch. 34 cutoff), but the other building (north building) may or may not be (we’re researching). If we have a scenario where one of the two is after 1979, would we be disqualified?
  • We would use the existing load-bearing masonry south building wall as our Fire Barrier, and add to it as needed to bring up to the required rating. If so, would we use the separation in Table 508.4 for sprinkelered (1-hour, which I think this wall would meet as-is) or non (2)?.
  • If this is a Fire Barrier, we’d have to have fire shutters and limitations on percentages of openings per 707.6, correct?
  • But if we have a new clerestory above the existing wall (see section), this would *not* need to be fire rated, correct?
Thanks!
 

Attachments

Great description of the scenario! Okay then. Take anything I say with a grain of salt. There is a rationale to my thinking but I am not going to divulge everything that goes into the details.

A two-hour barrier will be required between the sprinkled portion of the building and the non-sprinkled portion of the building. If both sides of the wall were sprinkled, than only a one-hour rating would be required. But where only one side is sprinkled, then we are looking at a 2 hour fire-rated barrier. This should extend 30 inches beyond the roof before reaching the clerestory windows.

That exterior wall probably has a 4 inch thick brick veneer. If the interior of that same wall has two layers of drywall or a thick layer of plaster, then I would call it equivalent to a two-hour assembly. Take a look at IBC Table 721.1(2).

The existing window openings could be protected with 90 minute fire shutters. If the addition is built entirely out of non-combustible materials, then I would accept replacing those windows with wire glass panels that measure no more than 54 inches tall and no more than 24 inches wide. Don't ask me why I would allow wire glass panels but it seems reasonable to me that anything equivalent to a 45 minute window assembly would be okay.

Your blue doors need to swing in the direction of egress. You probably knew that already.
 
One aspect missing from your description is the construction type for each existing building and the new addition. How does the building comply with allowable area requirements, since this particular provision in the Ohio Building Code applies to situations where the existing building plus the addition will exceed the allowable area?

The provision mentions "the existing building and the addition"--both singular references; but you have two existing buildings that you're connecting with an addition. Although I think you may be okay as you provided, you may want to have a meeting with the building department just to make sure everyone is on the same page and there are no surprises when it comes to plan review time.
 
Thank you cda, that's helpful. We'd considered the south existing building (B, S-2, non-sprinkelered) to be one fire area, and the addition plus the north building to be the other fire area.

We didn't think we'd need a Fire Wall based on this from Ch. 34, item 2 below.

3412.2.3 Additions. Additions to existing buildings shall comply with the requirements of this section.
...
3412.2.3.2 Additions to buildings of Groups other than R and I occupancies. When the combined height and area of the existing building and the addition exceeds the height or area allowed by Chapter 5 including any area increases permitted, the following shall be permitted:

1. A fire wall that complies with Section 706 shall be constructed between the existing building and the addition. When a fire wall is constructed to separate the existing building from the addition, the addition shall be considered a separate building.

2. A fire barrier that complies with Section 707 as required for separating fire areas shall be provided between the addition and the existing building. When a fire barrier is constructed to separate the existing building from the addition, all the following shall apply.

a. The combined height and area of the addition and existing building shall be used to determine the construction type and fire protection requirements for the addition.

b. The construction type of the existing building and the addition may differ.

c. Fire protection system is not required in the existing building when a fire protection system is required in the addition.

d. When calculating the allowable combined height and area of the existing building and the addition in accordance with Chapter 5, the tabular values corresponding to a building equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1 shall be used whether or not the existing building is provided throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

3. When the combined height and area of the existing building and the addition does not exceed the height and area allowed by Chapter 5, but the area of the existing building plus the new addition creates a fire area greater than the threshold limits of Chapter 9, one of the following shall be provided:

1. A fire barrier to limit the fire area; or

2. An automatic sprinkler system in the addition extends into the existing building to a barrier or partition.
 
We have been assuming Construction Type IIIB based on our assessment of the existing buildings. The south (non-sprinkelered building) is load-bearing masonry walls, and the north building is a block wall with bar joists warehouse.

We're right now working through the Ch. 34 Area calculations to determine how they will affect allowable area. I'm not experienced enough yet with Ch. 34 to understand how this will affect things, but if we are IIIB the addition plus north building, at about 25,000sf should be OK (based A-1, non-separated but 1 story and sprinkelered). The south building is over, I think (B allows 19,000 for non-sprinkelered, but S-2 is OK). We were hoping that between Ch. 34 and the fact that we are doing relatively minimal interventions in that building that we'd be OK, but that's one of the things I'm trying to figure out.
 
ETThompson said:
Thank you cda, that's helpful. We'd considered the south existing building (B, S-2, non-sprinkelered) to be one fire area, and the addition plus the north building to be the other fire area.

We didn't think we'd need a Fire Wall based on this from Ch. 34, item 2 below.

3412.2.3 Additions. Additions to existing buildings shall comply with the requirements of this section.
...
3412.2.3.2 Additions to buildings of Groups other than R and I occupancies. When the combined height and area of the existing building and the addition exceeds the height or area allowed by Chapter 5 including any area increases permitted, the following shall be permitted:

1. A fire wall that complies with Section 706 shall be constructed between the existing building and the addition. When a fire wall is constructed to separate the existing building from the addition, the addition shall be considered a separate building.

2. A fire barrier that complies with Section 707 as required for separating fire areas shall be provided between the addition and the existing building. When a fire barrier is constructed to separate the existing building from the addition, all the following shall apply.

a. The combined height and area of the addition and existing building shall be used to determine the construction type and fire protection requirements for the addition.

b. The construction type of the existing building and the addition may differ.

c. Fire protection system is not required in the existing building when a fire protection system is required in the addition.

d. When calculating the allowable combined height and area of the existing building and the addition in accordance with Chapter 5, the tabular values corresponding to a building equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1 shall be used whether or not the existing building is provided throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

3. When the combined height and area of the existing building and the addition does not exceed the height and area allowed by Chapter 5, but the area of the existing building plus the new addition creates a fire area greater than the threshold limits of Chapter 9, one of the following shall be provided:

1. A fire barrier to limit the fire area; or

2. An automatic sprinkler system in the addition extends into the existing building to a barrier or partition.
Click to expand...



Not my area

But to be considered two separate buildings

What is needed??


Not for area and height.
 
cda said:
Not my area

But to be considered two separate buildings

What is needed??


Not for area and height.
Click to expand...

Well, if we were trying to consider it as two separate buildings and reviewing it as new construction, we would need a Fire Wall, but we're trying to avoid that if possible. The language from Ch. 34 I quoted above seems to give us the option of a Fire Barrier instead, but we do have to then figure out if the rest of the Section 3412 analysis works.
 
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RLGA said:
One aspect missing from your description is the construction type for each existing building and the new addition. How does the building comply with allowable area requirements, since this particular provision in the Ohio Building Code applies to situations where the existing building plus the addition will exceed the allowable area?

The provision mentions "the existing building and the addition"--both singular references; but you have two existing buildings that you're connecting with an addition. Although I think you may be okay as you provided, you may want to have a meeting with the building department just to make sure everyone is on the same page and there are no surprises when it comes to plan review time.
Click to expand...

Yes, that is another issue that I'm wondering about. The language in 3412 says: d. When calculating the allowable combined height and area of the existing building and the addition in accordance with Chapter 5, the tabular values corresponding to a building equipped throughout with an automatic sprinkler system installed in accordance with Section 903.3.1.1 shall be used whether or not the existing building is provided throughout with an automatic sprinkler system in accordance with Section 903.3.1.1.

But if we consider this as non-separated, worst case (A-1) sprinkelered building, we're still over the allowable (34,000 allowed, we have about 60,000 total). But if we make the wall between the existing south building and the new addition a Fire Barrier, with fire shutters, at 2 hrs, that would seem to be an adequate separation. But I wouldn't think we could then look at the allowable for the overall...could we? Seems like we're going around in circles.
 
Option #1:
Chapter 5 allows us to consider a group of several buildings as a single non-separated building. The most restrictive provisions will need to be applied to the entire hodge-podge of structures with various types of construction, various type of occupancies, various smells and colors, etcetera.

Option#2:
Section 706 allows us to divide a single building into fire areas with horizontal and/or vertical fire walls in such a way that each side of the fire-rated assembly is a SEPARATE building. In other words, if the new addition (middle link) has roof framing that runs in the East-West direction and is not supported by the existing wall - after that wall is upgraded to a two-hour-rating, then we are done talking about the allowable area of all three portions combined. The allowable area for the North side of the 2 hour fire wall is calculated. The allowable area for the South side of the 2 hour fire wall is calculated.

Pick option #1 or #2.

Yes, there are alternatives to the wire glass window assemblies that cost $20 per square foot. There is always the fire rated glass assemblies manufactured by "SaftiFirst" for only $200 per square foot. Hmmm. Which option will you choose? How about filling in the existing window openings with solid brick for $50 per square foot?

Pick option A, B, C, or install new fire shutters.
 
Last edited:
BayPointArchitect said:
Option #1:
Chapter 5 allows us to consider a group of several buildings as a single non-separated building. The most restrictive provisions will need to be applied to the entire hodge-podge of structures with various types of construction, various type of occupancies, various smells and colors, etcetera.

Option#2:
Section 706 allows us to divide a single building into fire areas with horizontal and/or vertical fire walls in such a way that each side of the fire-rated assembly is a SEPARATE building. In other words, if the new addition has roof framing that runs in the East-West direction and is not supported by the existing wall - after that wall is upgraded to a two-hour-rating, then we are done talking about the allowable area of all three portions combined. The allowable area for the North side of the 2 hour fire wall is calculated. The allowable area for the South side of the 2 hour fire wall is calculated.

Pick option #1 or #2.
Click to expand...
For it to be a fire wall, it must be structurally independent. This is the number one tripping point I encounter in regards to fire walls.

706.2 Structural Stability
Fire walls shall be designed and constructed to allow collapse of the structure on either side without collapse of the wall under fire conditions. Fire walls designed and constructed in accordance with NFPA 221 shall be deemed to comply with this section.
​
Must also be mindful of horizontal continuity (706.5).
 
Right, but that is exactly why we are trying to avoid a Fire Wall, we do have the existing south building roof structure (large heavy timber trusses) bearing on this existing masonry wall (ie, runs N-S). It would also mean we'd need to brace the existing wall and probably add layers to the exterior side. We'd want to avoid adding layers to the interior side, because of the difficultly of framing around the trusses. We'd also definitely have to use rated glass for the clerestory (or abandon it), and finally the exterior side wall is a beautiful old brick wall which we'd like to have exposed. And all this is likely to add significant cost. That's why we're looking at Chapter 34 and a Fire Barrier.
 
A code-compliant fire sprinkler system in the entire structure solves may problems and maybe the most cost effective options. Then when the next change comes along you have the protection in place
 
TheCommish said:
A code-compliant fire sprinkler system in the entire structure solves may problems and maybe the most cost effective options. Then when the next change comes along you have the protection in place
Click to expand...

We know, but that is prohibitively expensive and not within our budget. We are doing minimal intervention in the south building, and not making it any less safe than it is now (the principle of Chapter 34), so we can't recommend to the owner that they do that. Worst case we will have to make the north wall of the south building a Fire Wall.
 
Yes, it may be, but our initial evaluation by the CM is that it would not be as much as the sprinkler system. We would probably have to build an independent freestanding wall to the north of the existing wall.

All of this is why we are trying so hard to avoid this and just use the Fire Barrier.
 
Maybe your budget is unrealistic, this is a construction saying that goes something like this Construction can be any 2 of the following list; inexpensive, fast, exceptionally good looking.

I would suggest you have the choice of 2 in this list; code compliant, easy to build, inexpensive
 
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