# Area increase not allowed for 13R sprinkler system.



## BayPointArchitect (Dec 16, 2011)

Given:

Three story apartment building, Type VB construction.

The NFPA-13R sprinkler system.

An architect who reads 903.3.1.2 to say that the 13R residential sprinkler system is an equal substitute for a NFPA13 system only in R occupancies of four stories or less.

Now I have read IBC 504.2 several times over and my interpretation is that both height and area increases are allowed for the full NFPA-13 sprinkler system.  But the 13R sprinkler system is good for only the height increase.

Would you concur with my interpretation that the 13R system does not allow for area increase?

Thanks!


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## cda (Dec 16, 2011)

Appears you are correct

506.3 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 building area limitation in Table 503 is permitted to be increased by an additional 200 percent (Is = 2) for buildings with more than one story above grade plane and an additional 300 percent (Is = 3) for buildings with no more than one story above grade plane. These increases are permitted in addition to the height and story increases in accordance with Section 504.2.

Exception: The building area limitation increases shall not be permitted for the following conditions:

1. The automatic sprinkler system increase shall not apply to buildings with an occupancy in Group H-1.

2. The automatic sprinkler system increase shall not apply to the building area of an occupancy in Group H-2 or H-3. For buildings containing such occupancies, the allowable building area shall be determined in accordance with Section 508.4.2, with the sprinkler system increase applicable only to the portions of the building not classified as Group H-2 or H-3.

3. Fire-resistance rating substitution in accordance with Table 601, Note d.


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## mtlogcabin (Dec 16, 2011)

Would you concur with my interpretation that the 13R system does not allow for area increase? :agree


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## Coug Dad (Dec 16, 2011)

area increase not allowed for non NFPA 13 sprinkler systems


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## gbhammer (Dec 16, 2011)

does not count :agree


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## BayPointArchitect (Dec 16, 2011)

Thanks everyone.


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## brudgers (Dec 16, 2011)

For what is worth, compared with SBC the area increases are cooked into the table already when it comes to group R.


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## TJacobs (Dec 16, 2011)

:agree  with all of the above.  Area increase = NFPA 13 only.


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## Builder Bob (Dec 20, 2011)

Be careful as a building area is allowed to be increased - I can add an extra story.

Allowable Floor Area is not allowed to be modified by a 13 R system.

However, they can still do an floor area modification based on open area.......


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## brudgers (Dec 20, 2011)

Builder Bob said:
			
		

> Be careful as a building area is allowed to be increased - I can add an extra story.  Allowable Floor Area is not allowed to be modified by a 13 R system.  However, they can still do an floor area modification based on open area.......


  Only relevant if they are of type V construction because adding another story to buildings of other construction types will exceed the 4 story limit for 13R (and obviously, this is limited to residential occupancies).


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## jpranch (Dec 20, 2011)

Seen it, been there, done that. The trick is educating the design professional. You DO NOT get an area increase for 13-R. I would suggest having the design professional call the ICC  for a code opinion to confirm. If he or she is not a member of the ICC perhaps you could email the question to staff?


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