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IBC Section 509.4

If the S2 parking is Type IA construction for a closed garage would the horizontal separation be 1-Hr as well? (S2 to R2 per Table 508.4)
 
If the question is can you use two separate methods of compliance for each portion of the building. The answer is yes if the building is separated by 3-hours fire wall.

Each portion of a building separated by fire wall(s) is considered a separate building and is evaluated for compliance with height, area and story individually. Also, I think 2-hours as shown will be required for the horizontal separation between Garage and R-2.
 
SAT said:
If the question is can you use two separate methods of compliance for each portion of the building. The answer is yes if the building is separated by 3-hours fire wall.Each portion of a building separated by fire wall(s) is considered a separate building and is evaluated for compliance with height, area and story individually. Also, I think 2-hours as shown will be required for the horizontal separation between Garage and R-2.
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The building is being classified as a Type IIIB for height and area purposes. My allowable area is 55,840 sf per floor while my actual is only 13,870 sf. The allowable height of 75 feet also exceeds my actual of 65 feet (at left side of diagram).

The question is can Table 503.1 be used for one side (producing a 5 story building with a basement) while using Section 509.4 on the other (producing a 5 story R2 over and S2 garage as indicated) so long as both the horizontal separation and vertical separations are maintained. My understanding from the code commentary is that while a 2 hour separation is required, it can be reduced to one hour by the mandatory sprinkler requirement for the R use and providing sprinkler protection in the garage.
 
I believe you can. Each side evaluated separately is in compliance.

What code Section are you referencing for the reduction from 2-hours to 1-hour? I am using 2009 IBC
 
+ & +



annoyitated,

Which code section(s) provide the most restrictive application

to your question [ RE: Section 102.1, `12 IBC ] ?

Also, ...which code \ standard & edition are you using ?

FWIW, ...I agree with **Skip Harper** Section 509 is for

Incidental Uses [ in the `12 IBC ] and would not apply to

your particular application.

+ & +
 
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I am using 2009 IBC. As far as I can see 509.4 doesn't mention Incidental Uses - it is titled "Parking beneath Group R".

Table 508.4 is referenced in the commentary of 509.4 allowing the reduction to 1 hour if both the R and S uses are protected with sprinklers.
 
1-Hr horizontal separation is required between S2 and R-2. Type IA construction requires 2-Hr. floor construction I think most restrictive rules.
 
SAT said:
1-Hr horizontal separation is required between S2 and R-2. Type IA construction requires 2-Hr. floor construction I think most restrictive rules.
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Per 509.4 it only needs to be Type I. If I use IB would it not be 1 hour, i.e. as the roof of the IB structure? Again, I am only going by the code commentary provided by IBC.

Just as a side note, I do not have an issue with both the horizontal and vertical separations staying at 2 hours. I just would like clarification to what I am reading in the code commentary which doesn't even mention Table 601. The bigger question is can you use the concept of 509.4 for only part of the building that has parking below it.
 
I see your note about the 2009 code annoyitated-I thought if a building required sprinklers then you could not claim an increase however I am still searching to backup my statement.
 
The horizontal separation I was considering it as a floor assembly and using Type IA or IB requires 2-Hrs. Also I think, Table 601 is mentioned by specifying construction type. My thoughts.
 
I think this limits it to a 4 story:504.2 Automatic sprinkler system increase. Where a building is equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1, the value specified in Table 503 for maximum building height is increased by 20 feet (6096 mm) and the maximum number of stories is increased by one. These increases are permitted in addition to the building area increase in accordance with Sections 506.2 and 506.3. For Group R buildings equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.2, the value specified in Table 503 for maximum building height is increased by 20 feet (6096 mm) and the maximum number of stories is increased by one, but shall not exceed 60 feet (18 288 mm)or four stories, respectively.
 
Not sure how you came up with the allowable sf per floor but see 506.4 the aggregate area of all stories limited to the sum of 3 stories above grade.
 
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Skip has the 4 story max, now that I look at it, and FV brings up a good point but it might be moot if you have to lose a story...(16,000X3 + frontage increase+?)
 
skipharper said:
I think this limits it to a 4 story:504.2 Automatic sprinkler system increase. Where a building is equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1, the value specified in Table 503 for maximum building height is increased by 20 feet (6096 mm) and the maximum number of stories is increased by one. These increases are permitted in addition to the building area increase in accordance with Sections 506.2 and 506.3. For Group R buildings equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.2, the value specified in Table 503 for maximum building height is increased by 20 feet (6096 mm) and the maximum number of stories is increased by one, but shall not exceed 60 feet (18 288 mm)or four stories, respectively.
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But if I elect to use NFPA 13 (903.3.1.1) I can go to 5 stories, correct?
 
I think that is fine so long as table 601 note d is not a issue. If you do not use the sprinkler system to protect the exterior walls it could give you the increase using a 13 as opposed to 13R
 
Not my intent to sidetrack the OP but footnote d was deleted in the 2015 based upon the misuse and extremely limited use. It was intended that a building utilizing the automatic fire-sprinkler system as a substituion for 1 hour fire-resistance-rated construction still be classified as a Type IIA, IIIA or VA building. However the building of respective Type B provided height and area advantage not using footnote b.

See Sigificant Changes to the 2015 IBC for further details.
 
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