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Two story apartment NFPA 13R and sprinklers in the attic.

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SprinklerDesigner2

Mechanical
Nov 30, 2006
1,251
I have a 2 story apartment building that appears to have a problem but on the good side the problem is not mine.

Remember here my job is to lay out the fire sprinkler system in accordance what the architect or project professional engineer tells me to do. If a a professional engineer or architect signs and seals drawings that he gives out telling the design is per NFPA #13R that is exactly what I will do. For me to do otherwise is folly in my opinion.

On drawing A-1 "Gross project area" is 14,360 sq ft..

Applicable codes are 2012 NFPA 101 and 2012 IBC.

Occupancy Classification is R2

Type of Construction VB

Max. Allowable Area Per Floor 7,000 SF 7,180 SF/FLR (W/Area Increase)

As you know Table 503 appears to limit floor area to 7,000 SF but the building is 7,180 SF which tells me the architect used frontage or something other than sprinkler to allow a larger foot print. Whatever he did it's not my problem.

There is a sprinkler drawing sealed by a professional engineer that has:

30w7zn8.jpg


2" riser makes it obvious, or should be anyway, that sprinklers in the attic were never intended. As well NFPA #13R is clearly called out.

Pretty simple, we bid the job, got it and just finished up the drawings today with hope of turning them in tomorrow. If I don't know the local plan examiner I usually try to make contact to ask if there is "anything special" he wants as a courtesy call.

#1 FDC out by curb. Ok, not a problem the engineer of record showed in on the drawings so it's a change order or someone else can install it.

#2 (This is a biggie) Fire sprinklers are required in the attic. Typical wood attic with 5 in 12 bitch the whole nine yards. Water supply was 59 static, 24 residual flowing 768 gpm. Bottom of the roof rafters is 18' above grade. Having to maintain a minimum 10 psi "safety factor" in accordance with Georgia fire marshal requirements there's a bit of a problem here.

I asked why sprinklers where required in the attic and was told the required fire separation between units was not adhered to. I didn't see any drywall partitions separating dwelling units in the attic (the building is already up) and on the first floor I didn't see what I would normally see as far as fire separation between dwelling units.

The only thing mentioned was the attic but I have a feeling there's a big problem with the interstitial space between floors. 2"x4" wood web joists 16" OC.

OK, I get it... definitely not my call (I wouldn't call this if you paid me) but my question is would sprinklers solve the problem of separation between dwelling units?

I am not going to use or share what I learn here outside the group... I guess I am more curious than anything.
 
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My comment doesn't really relate to your issue at hand, but:

"Typical wood attic with 5 in 12 bitch the whole nine yards" made my day. That's generally how I refer to attics as well.

R M Arsenault Engineering Inc.
 
I agree that we should be able to do what the Professional of Record states on the drawing. However, I was taught basic reading comprehension early in my schooling, so I don't mind asking a question of the POR in cases where something sends up a red flag for me.

I am no IBC expert by any means. But, it may have to do with draft stopping not being provided.

If you look at IBC (2003 edition) 717.4.2 it talks about draft stopping and R2 occupancies.

It is not required if equipped with sprinklers per 903.3.1.1 (NFPA 13)

In R2 <4 stories, draft stops every 3000 sq ft or above every 2 dwelling units whichever is smaller. If the architect did not show draft stopping, then 13R is out the door.

Lastly, exception #4 states draft stopping not required with 903.3.1.2 (13R) if you have sprinklers in concealed combustible spaces.

These excerpts were from the 2003 IBC. It is very similar in IBC 2012 (718.3). Basically, draft stopping is going to be required in this attic unless you put sprinklers in there.

This is one of my major pet peeves. Design professionals take sprinkler tradeoffs, but don't get into the full implication of them. Everyone on the project called out NFPA 13R. You as the contractor should be bidding per NFPA 13R. Sprinkler contractors are guys that deal with standards from NFPA. Sprinkler contractors should not be required to be building code experts as well. However, we are often the only ones that seem to catch this crap. It is obviously a change order to you because everyone stated NFPA 13R on the contract documents. I would just make the change order so freaking high cost, that it is obviously less expensive to put the draft stops in the attic. If they don't, that exception #4 is going to kill you. I read that as ALL concealed combustible spaces - between floors as well. This is going to mean specially listed sprinklers and they will likely need draft curtains for the sprinklers unless the space is already compartmentalized to 1000 sq ft. Also, that attic is likely a dry system, so you are looking at a design area of 2535 sq ft. Due to over discharge and such, you are looking at about 500 gpm demand for the attic with hose. Try pushing that through a 2" fire line with the pressures you described. I think it is time for an intervention for the design professionals on the job.

Sorry if I sound a bit jaded on this today. I have literally dealt with this 3 times this week where the design professional has prescribed the incorrect standard because of building trade-offs or something else. In one case, the POR called a steel and concrete R-2 occupancy job Type VA construction. All of the details show steel structure, metal joists, sheet rock, etc...not a damn piece of combustible construction. He then used the sprinkler increase (and called it 13 system) to get the area - at least he applied that correctly. But, after we questioned his construction type, it turns out it was not VA. They didn't need the area increase and a 13R system would be acceptable for the project. The architect thanked us for bringing the question and it was able to save a fair bit on the project. But, that is stuff that we shouldn't even be looking at. We should be able to read a code analysis that says 13 or 13R and do our job.

Travis Mack
MFP Design, LLC
"Follow" us at
 
skdesigner.

OMG! My spelling checker said it was good to go so... but yeah, in many cases an appropriate description.

Travis,

The wood framing is 100% completed and I felt it a bit odd not to see any drywall between the dwelling units but I just figured it was something they would do later.

Like you said our job is not to review the entire project to insure draft stopping is in accordance with codes and standards.

Jaded, looked at one today involving a two story classroom building similar to the one you describe, not a bit of combustible material in it. Second floor is 14' above grade so no standpipe is required Water supply is 56 static, 45 residual flowing 900 gpm and for the life of me I can not figure out why there's a 750 gpm 80 psi fire pump with a 40 hp motor specified. I know I could lay this out without a pump (worst case is OH1) and easily give a 15 psi safety factor so why the pump?

 
I don't think you have a problem under the 2012 IBC as it relates to allowable area. I don't have a site plan but I am pretty sure the architect took an area increase based on the location of the building in relation to exposure buildings or its frontage separation from property lines. See IBC Section 506.1.

Travis is correct that draft stopping is required, and this is a commonly missed IBC requirement.

Maybe what I should do for you folks is post my matrix of IBC requirements based on a building being protected by either a NFPA 13, 13R or 13D sprinkler system.
 
stookey: Yes Please.

It isn't our job. However; we must also consider "due diligence". It can bite us because we are hired as professionals.
If there is a doubt, or even if we are sure, that the bid documents are incorrect, I feel we should at least put forth the effort.
On this very topic I have lost a job and even gotten the job solely because I was the one to bring it up.
When it is not possible or probable to bring it up beforehand, I include an Option #1 on the bid to provide a 13 compliant system, with the words "If Required".
Due diligence done.

R/
Matt
 
Stookey,

I wasn't concerned about the 7,180 sq ft because the building is separated all the way around with parking lot in front, four tennis courts in back at 31' at each end. I figured he knew what he was doing and increased his building area by clearance.

Matrix! Matrix! Matrix!
 
Matthew,

If I spot something I will always bring it up outlining what I think but including the phrase to the effect "this advice is worth exactly what you are paying for it which is nothing" followed by a strong recommendation that they get together with their building design professional who is responsible for the project.

Due diligence where I can.
 
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