# Mixed use - Construction Type analysis



## Jay (Jun 15, 2018)

Hello all,

I had been discussing this building project in another thread with regard to fire separation distance...I am now here looking for some guidance with regard to construction type.  Mentioning in case this project looks familiar to some.  

Essentially, my question is this:  With a mixed use building, does one look at each use individually in order to analyze maximum floor areas and heights per Table 506.2 or is there another method, like adding up all floor areas for each use, and then using the most stringent condition (floor area) to determine Construction Type per Table 506.2?

New 11,000 s.f. two-story, mixed use building will connect to an existing 1,800 s.f. building.  No access between buildings, they just connect primarily for aesthetic reasons.   Same lot, same owner.  This is a non-public catering facility first floor with private offices on second floor.

Total new floor area is 11,000 s.f. as follows, total of both floors:
"F1" use - 3,400 s.f.
"B" use - 6,000 s.f.
"S2" use - 1,600 s,f,

If I add the existing building in order to analyze them as one building that adds 1,800 s.f. of "B" use, still below the requirements to classify this as 5B and not need a sprinkler system, from what I can tell.  For example, non sprinklered B use is max 9,000 s.f. for 5B construction and I have 7,800 s.f.

As you can see from the areas above, I am below what seems to be the most stringent requirements of table 506.2 if I am in fact looking at the most stringent use, and also below the height limitation as this building is about 33 feet tall.

I realize I will need some rated walls where connecting to the existing building and also adjacent to a new exterior exit access stair from the second floor to grade.

Thus, it would seem I am ok with looking at this entire assembly as one building and ok with no sprinklers. In particular, the Fire Protection Systems chapter mentions some exceptions for sprinklers in F1 under 903.2.4 (Sprinklers needed if floor area exceeds 12,000 sf) . Same for other uses in that chapter.

Appreciate your insight.
Thanks


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## cda (Jun 15, 2018)

http://www.specsandcodes.com/articl...lding Classification Part 1 - Occupancies.pdf


http://www.specsandcodes.com/articl...lassification Part 2 - Construction Types.pdf


http://www.specsandcodes.com/articl... Applying the Building Code during Design.pdf



http://www.specsandcodes.com/articles/default.html


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## Builder Bob (Jun 15, 2018)

it depends - separated or non -separated -


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## Jay (Jun 15, 2018)

I'm looking at this as non separated.

cda, that is a wealth of info.  Thanks.


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## cda (Jun 16, 2018)

Jay said:


> I'm looking at this as non separated.
> 
> cda, that is a wealth of info.  Thanks.




Thank rgla!!!

And he is a great author

https://www.barnesandnoble.com/w/applying-the-building-code-ronald-l-geren/1124180145

money well spent


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## RLGA (Jun 16, 2018)

cda said:


> Thank rgla!!!
> 
> And he is a great author
> 
> ...


Thanks, dca 

If nonseparated, use the most restrictive occupancy group for height and area.


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## Jay (Jun 16, 2018)

Thanks Ron.  I sent you a private email btw, hope it came through.

I'll be plugging my criteria into your Fire Station sample to see what I come up with.

In the meantime, by most restrictive, are you referring to max. floor area per the construction type I am looking for?

Meaning....
B use, 5B non sprinklered = max 9,000 sf
F1 use, 5B, non sprinklered = max 8,500 s.f.
S2 use, 5B, non sprinklered = max 13,500 s.f.

Thus F1 is the most restrictive at 8,500 s.f. floor area so that would be the maximum area per floor if I want to use 5B and no sprinklers.   
With my first floor at 6,000 s.f. total I appear ok.


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## RLGA (Jun 16, 2018)

Just to make sure I understand, the new building is 6,000 sq. ft. on the first story (Group B) and 5,000 sq. ft. on the second story (Groups F-1 and S-2). An existing building, to which the new building is attached, is 1,800 sq. ft., thus making the first story (if considering new and existing as one building) 7,800 sq. ft. You want to use Type VB construction and have nonseparated occupancies.

If the above is correct, then you don’t have a problem with allowable area, but you do have a problem with allowable height. Group F-1 may allow 8,500 sq. ft. per story, but it also only allows a single story building. Thus, you’ll have to install a sprinkler system to get the one story increase for height or change your construction to Type VA, which allows Group F-1 to have two stories.


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## cda (Jun 16, 2018)

Jay said:


> Thanks Ron.  I sent you a private email btw, hope it came through.
> 
> I'll be plugging my criteria into your Fire Station sample to see what I come up with.
> 
> ...





S-2 do not normally fly to often !!!

Unless you are storing non combustible materials


So what is your S-2???

Or is it a parking garage?


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## Jay (Jun 16, 2018)

Ron, that's almost correct.  

F1 is actually on the first floor, along with some B use.  Second floor is all B use.  

CDA, first floor also includes some S2 which in reality is storage for food products, some paper goods, glassware, etc...all things the catering company needs.  As I look back at S1 I see that it does in fact include paper items.  Good looking out!  I need to get some better specifics from client on what exactly will be in there.  

Here's a monkey wrench for ya.....the first floor storage space of about 1,000 s.f. is actually going to be the full height of the building (2 stories tall).  They don't want a second floor there because they plan to store things tall, on shelves.  I'll need to research if there is a height limit on "one story".

More importantly, can you foresee any possibility of getting the F1 use in this 2 story building with VB construction type without having to sprinkler the building?  Perhaps by isolating the first floor as a separated space?  If I have to go to VA so be it, will probably be more cost effective to use VA construction than sprinkler the building.

Thanks gents. And Happy Fathers Day to all the Dad's out there!


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## cda (Jun 17, 2018)

So the main business is

Catering??

Could possibly be a “B”. And not F-1


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## RLGA (Jun 17, 2018)

Jay said:


> Ron, that's almost correct.
> 
> F1 is actually on the first floor, along with some B use.  Second floor is all B use.
> 
> ...


To use Type VB, you’ll need to separate the Group S-2 from the Group B with a 2-hour horizontal assembly per Table 508.4. This means that the walls supporting the 2-hour horizontal assembly will need to be of 2-hour construction, as well. It’s probably better to just go with Type VA construction, which only requires 1-hour construction throughout, except for interior non load-bearing walls.


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## Jay (Jun 17, 2018)

cda said:


> So the main business is
> 
> Catering??
> 
> Could possibly be a “B”. And not F-1



Hmmmm, that's interesting.  The first floor actually contains 2,400 s.f. of primary food processing area for the owners (not including a 300 s.f. "scullery", which I believe will ultimately be included as part of the food processing thus the total primary kitchen / catering is 2,700 s.f.  Then there is a secondary, first floor rental kitchen around 800 s.f. which they will rent out for other caterers.  The rental kitchen is only accessed from a separate exterior entrance.

I have been looking at the first floor F1 use as the total kitchen / food processing (not including scullery at this time) area of 2,400 + 800 = 3,200 s.f......over the 2,500 s.f. maximum for B use.

I am not as familiar with commercial work, still digging through the codes and reading up on Ron's articles, but perhaps there is some avenue of looking at these two kitchens separately to obtain the B use status which allows 2 stories and VB construction?


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## Jay (Jun 17, 2018)

RLGA said:


> To use Type VB, you’ll need to separate the Group S-2 from the Group B with a 2-hour horizontal assembly per Table 508.4. This means that the walls supporting the 2-hour horizontal assembly will need to be of 2-hour construction, as well. It’s probably better to just go with Type VA construction, which only requires 1-hour construction throughout, except for interior non load-bearing walls.



If this were standard construction I would have no hesitation to use VA from the get go.  What I failed to mention is these clients are considering the building shell be built as a pole barn structure with truss roof.  The exterior walls consist of structural posts and horizontal 2x framing supporting a possible steel siding.  Not much there.  This is why I have been trying to work with VB if possible.  Sorry for withholding this info, it's early in design and no firm decisions have been made as of yet.  There will be some detailing involved to get this exterior wall assembly 1-hour rated.  Again, weighing the costs of doing all that versus possible sprinklered building.

The storage area (S1 or S2 tbd) is in the back corner of the building and as mentioned, two stories tall.  Does the 2-hour fire separation apply to the roof structure, thereby applying to the two outside exterior walls supporting that roof structure as well?


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## Jay (Jun 17, 2018)

Jay said:


> If this were standard construction I would have no hesitation to use VA from the get go.  What I failed to mention is these clients are considering the building shell be built as a pole barn structure with truss roof.  The exterior walls consist of structural posts and horizontal 2x framing supporting a possible steel siding.  Not much there.  This is why I have been trying to work with VB if possible.  Sorry for withholding this info, it's early in design and no firm decisions have been made as of yet.  There will be some detailing involved to get this exterior wall assembly 1-hour rated.  Again, weighing the costs of doing all that versus possible sprinklered building.
> 
> The storage area (S1 or S2 tbd) is in the back corner of the building and as mentioned, two stories tall.  Does the 2-hour fire separation apply to the roof structure, thereby applying to the two outside exterior walls supporting that roof structure as well?



I recall reading, and now see again from Ron's article on Fire Resistive Construction, that the horizontal separation applies to floors and roofs.


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## cda (Jun 17, 2018)

If it works for you, you can always submit to the ahj and see if it fly’s or crashes



*304.1Business Group B.*
Business Group B occupancy includes, among others, the use of a building or structure, or a portion thereof, for office, professional or service-type transactions, including storage of records and accounts. Business occupancies shall include, but not be limited to, the following:


Food processing establishments and commercial kitchens not associated with restaurants, cafeterias and similar dining facilities not more than 2,500 square feet (232 m2) in area


Some how break up the kitchen to get under

Storage room or other


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## RLGA (Jun 17, 2018)

Jay said:


> I recall reading, and now see again from Ron's article on Fire Resistive Construction, that the horizontal separation applies to floors and roofs.


Don’t confuse horizontal assembly and horizontal separation. Although not defined in the IBC, *separation* is used when describing the construction between spaces for various purposes, and typically does not include the roof. A horizontal *assembly* includes both floors and roofs, and the fire-resistance rating is determined by Table 601. When a floor is used as an occupancy separation, then the fire-resistance rating is determined by Table 508.4. If not for an occupancy separation, a floor may also have a fire-resistance if used for a horizontal allowance per Section 510.2, dwelling/sleeping unit separation per Section 420.3, incidental uses per Section 509.4.1, control areas per Section 414.2.1, and fire areas per Section 711.2.4.2. If a floor serves as a separation for two or more of the purposes listed above, then the most restrictive (i.e., highest) fire-resistance rating must be used.


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## RLGA (Jun 17, 2018)

cda said:


> If it works for you, you can always submit to the ahj and see if it fly’s or crashes
> 
> 
> 
> ...


Or, consider your storage as Group S-1. Per Table 508.4, there is no requirement to separate Groups B, F-1, and S-1; and as long as the Group F-1 is located on the first story, then you can classify the building as Type VB with separated occupancies, because the required separation between the occupancies is “N” (no separation requirement).


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## Jay (Jun 19, 2018)

Thanks for that Ron.

Am I understanding you correctly in that there is a possibility of getting F1 use to be allowed in this two story, VB, non sprinklered building?


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