Design ideas for a NFPA 13 Residential Occupancy
Design ideas for a NFPA 13 Residential Occupancy
(OP)
I am running into some issues on a somewhat unique design for an apartment complex in SLC. Due to the close proximity of adjacent buildings in the area. The builder cannot provide FD access within 150' of all portions of the structure per the IFC. The AHJ has requested, as an alternate means of fire protection, that the design densities in the fire suppression system to be increased a level. Therefore, parking areas will be designed with a .2 design density and residential areas with a .15 design density.
This is not so much of an issue in the parking garage but it is in the apartment areas. The contractor is requesting concealed flat plate pendents in all areas. with a residential head I will have a 4.9 k-factor head of a 5.6 factor head from Reliable. If I use a 16x16 spacing my end head pressure will be (.15*256/4.9)^2=61.41 psi or (.15*256/5.6)^2=47.02 psi respectively. Along with highest outlets being at 50' above the flow test point, adding an additional 21.65 psi to the required pressure for the system. That is even before I start adding friction loss in the pipe so I'm sure you can see my dilemma. A simulated fire flow for the area was 106 Static and 20 psi @ 3000 gpm. I will know the actual numbers next week.
Our hope is to do all residential areas in CPVC and to obviously keep pipe sizes as small as possible. My question is what are some design ideas that I may use to achieve the best and cheapest design possible? I thought about using a commercial head instead of a residential head. That way I can use a most demanding room design approach which would still have me calculating 4 heads in a unit (+2 in coordinator). This would allow me to avoid flowing 4 sprinklers on one branch line and would instead push me to where each compartment has a max of 2 heads on a single branch line. Higher k factors would also help the end head pressure.
I also thought about looping each floor using another standpipe, that would add another floor control assembly for each floor.
Does anybody have any other ideas I may be overlooking or any advice for me on this kind of design? Thanks
This is not so much of an issue in the parking garage but it is in the apartment areas. The contractor is requesting concealed flat plate pendents in all areas. with a residential head I will have a 4.9 k-factor head of a 5.6 factor head from Reliable. If I use a 16x16 spacing my end head pressure will be (.15*256/4.9)^2=61.41 psi or (.15*256/5.6)^2=47.02 psi respectively. Along with highest outlets being at 50' above the flow test point, adding an additional 21.65 psi to the required pressure for the system. That is even before I start adding friction loss in the pipe so I'm sure you can see my dilemma. A simulated fire flow for the area was 106 Static and 20 psi @ 3000 gpm. I will know the actual numbers next week.
Our hope is to do all residential areas in CPVC and to obviously keep pipe sizes as small as possible. My question is what are some design ideas that I may use to achieve the best and cheapest design possible? I thought about using a commercial head instead of a residential head. That way I can use a most demanding room design approach which would still have me calculating 4 heads in a unit (+2 in coordinator). This would allow me to avoid flowing 4 sprinklers on one branch line and would instead push me to where each compartment has a max of 2 heads on a single branch line. Higher k factors would also help the end head pressure.
I also thought about looping each floor using another standpipe, that would add another floor control assembly for each floor.
Does anybody have any other ideas I may be overlooking or any advice for me on this kind of design? Thanks





RE: Design ideas for a NFPA 13 Residential Occupancy
I have dealt with similar in SLC. I would try some things with your sprinkler coverages.
1 - The way to determine area of coverage (assuming the compartments meet small room criteria) is to take area of compartment divided by number of sprinklers. You then apply the 0.1 density or the sprinkler listing, whichever is greater. I would see if you can get the AHJ to allow you to apply the 0.15 and compare to the listing.
For example, if you have a 600 sq ft compartment and it is covered by 4 sprinklers, the sq ft per sprinkler would be 150 sq ft. At 0.15 density, that is 22.5 gpm. You could compare that the sprinkler listed flow for your spacing. Obviously the 22.5 is greater than 20gpm for 20' spacing. So, you could have your sprinklers spaced at 10' off walls and still be OK. Also, your end head pressure would be a lot less than your 47 psi above.
This should be OK since the space is still light hazard no matter how much water the AHJ is requiring. You are following the criteria for determining area of coverage when utilizing residential sprinklers.
2 - As you mentioned, you can use the commercial extended coverage sprinkler. I can't recall if there is a flat plate concealer at 20' spacing. I think you can get some at 135°F instead of the typical 155. That could be an option, but flows will be a lot bigger. In the example I mentioned above, 4 commercial ex cov would be just over 150 gpm vs 4 residential at just under 100 gpm flows.
3 - I would avoid interconnecting the standpipes unless absolutely necessary because you will need another floor control assembly (minus flow switch and drain) and it is a real maintenance issue to have to shut two valves to work on a floor.
Shoot me an email or give me a call if you need any other ideas. These are always fun projects with the extra requirements that make sense, but the little details don't get thought through all the way as you are finding out.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
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RE: Design ideas for a NFPA 13 Residential Occupancy
What does upping the density in an apartment get you???
Is the attic going to be sprinkled??
If not offer that, sprinkle all enclosures, breeze ways/ corridors,
See if that makes them happy
RE: Design ideas for a NFPA 13 Residential Occupancy
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Design ideas for a NFPA 13 Residential Occupancy
Does he want to drive the truck around the building? NFPA #13 allows us to not provide the FDC when the building is remotely located.
Beefing the density does nothing. Sprinklering the Entire building does as cda mentioned.
For an example, do the major cities where high rises sit close together up the density?
The sprinkler effectiveness is about speed. The flowing water is secondary. Hooking up to the FDC is like 4th or something..
R/
Matt
RE: Design ideas for a NFPA 13 Residential Occupancy
It was clearly noted at bid time in the specifications that the densities were to be increased. I don't remember if the AHJ was mandating everything to be classified as OH1 as a minimum. If they classify as OH1, then cpvc is also out. But, I believe it was just the density increase.
It's always fun when you are dealing with places where things are just done arbitrarily because it is thought to be a good idea, but no one has gone through all of the minutia and how it impacts everything else.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Design ideas for a NFPA 13 Residential Occupancy
OP had classified it as unique problem with a suggested resolution.
I am all for it if defined and is a level playing field.
R/
Matt
RE: Design ideas for a NFPA 13 Residential Occupancy
They are definitely set in the ways they work. That particular jurisdiction is like military. They are very strict and implicit what they require. They are also good to work with.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Design ideas for a NFPA 13 Residential Occupancy
That does lead me to a question though. The upper lever of these apartments have a loft that sits above the kitchens and looks out onto the living room area. From my understanding, that entire area loft +kitchen & living area would be considered one compartment. Is that correct? The floor area of the compartment isn't larger than 800 ft squared but would the fact that there are two ceiling levels in the compartment make it ineligible for a "small room" under the opening requirements?
Matthew - As Travis said, this is typical for this jurisdiction. In fact, All but one of the projects we have done in this jurisdiction have used this alternative method because a certain aspect of the IFC couldnt not be satisfied due the close proximity of surrounding buildings. Like Travis said, they are very particular in what they want and as far as understanding NFPA and its application, they know their stuff better than most jurisdictions. There is only one person in particular that I dislike dealing with. Otherwise they are pretty good to work with.
RE: Design ideas for a NFPA 13 Residential Occupancy
I would definitely try to get them on the phone after you do some more calcs to see the impact of everything. You will want to make sure they are on board with these options prior to getting the full design done and finding they say NO!
My biggest concern you have is if they are classifying it all as OH1 instead of just mandating an increase in density. You can do light hazard and be above the minimum density without issue. However, if they are trying to call the areas ordinary hazard, I don't believe you can use residential sprinklers. Also, you will not be able to use CPVC as the continuous spaces will exceed 800 sq ft, which eliminates the use of CPVC. I would clarify that ASAP. It could really be a game changer on that project.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Design ideas for a NFPA 13 Residential Occupancy
I actually went through and ran a bunch of calcs and it seems I am able to get them all to work. More 1 1/2" on branch lines than we usually like on these type of jobs, but we knew that before bidding so it should be fine. I have requested information from the AHJ for the design areas. I believe they will be designed under their true hazard classifications with only a density increase. That's what the approved Alternate Means and methods for states. I am going to make sure first though.
Travis, thanks for your help. Do you do a lot of work in Utah? I have actually ran across your plans a few times on projects and they are always well done. Glad to have you on the forum to share your expertise.
RE: Design ideas for a NFPA 13 Residential Occupancy
That is great about the increase in density and not an increase in classification. Hopefully the AHJ will agree and you guys can have a nice, profitable project.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Design ideas for a NFPA 13 Residential Occupancy
A lot of this comes down to MEP engineers not knowing $hit when it comes to the fire protection design issues in these buildings and the owner gets to pay for that when it takes me 4 plan reviews to get the plans corrected to a point where I can comfortable issue a permit to proceed.
As to the OH-G1 density in the dwelling sleeping units, this was most likely part of the Alternative Method of Compliance (AMOC) I suspect. The architect said, yeah sure just give me the permit, and off to the races he went. I would hope the architect submitted the AMOC in writing because if he did, you need a copy because other requirements may have been imposed.
Sorry for your pain but welcome to Cities in A Box.
RE: Design ideas for a NFPA 13 Residential Occupancy
Besides the parking garage, what other requirements have you put on them ?
We are getting an apartment with the parking garage in the middle, but I do not think anything else.
Are you dividing the building up with fire walls?
Any other sprinkler requirements??
RE: Design ideas for a NFPA 13 Residential Occupancy
We actually helped with the Alternate means and methods in the design build process. It is presented before a committee and needs approval. This is typically the only thing that they will buy off on in my experience. We have tried other things with no luck.
I don't blame the FD department at all. We definitely knew it going into the project and planned for it in our bids. It should be a great project for us. I was just seeking ideas that would help the design to not get too crazy since I was running into some problems. Not really trying to complain about the AHJ as they are just doing their job.
RE: Design ideas for a NFPA 13 Residential Occupancy
These buildings of lightweight construction do scare me to have guys running into them when they are smoke filled and limited to zero visibility. It would be interesting to see some fire modeling of the benefits of increasing the density to some other alternative means of protection.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Design ideas for a NFPA 13 Residential Occupancy
One option is truss sprinklers, but again, the architect needs to understand up front this means draft stopping. The architect correctly understands that draft stopping is not required IBC Chapter 7 when a NFPA 13 system is employed doesn't understand that it is required to ensure successful sprinkler operation.
Travis, the performance sprinklers in conjunction with light weight construction (or as I call it math versus mass construction) has been well documented by UL in a number of fire tests. Reliability of the valve is paramount. I would advocate a chain & lock with electric supervision, especially when floor control valves are located in stairs.
RE: Design ideas for a NFPA 13 Residential Occupancy
I'm glad to hear that the sprinklers and lightweight construction has done well in fire testing.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Design ideas for a NFPA 13 Residential Occupancy
Fire flow reduction,
What per centage have you been allowing in this type of building set up?
RE: Design ideas for a NFPA 13 Residential Occupancy
But it is damn refreshing seeing intelligent conversation on these topics....
R/
Matt
RE: Design ideas for a NFPA 13 Residential Occupancy
One other thing: I hate trash chutes. After Dallas FD had the firefighter LODD last year in the apartment building where the waste and debris in the chute was a contributing factor, we've started looking at these much closer. They take a beating so the required shaft opening protectives and the shaft itself requires continuous scrutiny.
RE: Design ideas for a NFPA 13 Residential Occupancy
Thanks, we may have a fire flow problem where they want to put this.
And yes I have pictures of trash chute/ laundry chute doors that do not close or proped open
RE: Design ideas for a NFPA 13 Residential Occupancy
If you do have a fire flow problem, go full NFPA 13 and further stipulate the combustible concealed spaces require AS protection. When the shop drawings arrive, make sure you have the correct details for the truss sprinklers. I require the shop drawings to illustrate the draft stop locations, the area boundary within each draft stopped bay, and the manufacturer design detail. Make darn sure the inspector's cannot accept a sprinkler substitution. There are small but very important differences between the various Truss sprinkler manufacturers.
RE: Design ideas for a NFPA 13 Residential Occupancy
I am getting lost in the truss sprinkler and draft stop issue
Can you give me a ref in 13
Do you mean the floor ceiling assembly protection?
If so I do know about that.
RE: Design ideas for a NFPA 13 Residential Occupancy
Also, be away that if you have TJI and specially listed sprinklers, TJI space must be fully insulated and it has to be wired in place.
These sprinklers have very specific requirements that must be adhered to in order to be in compliance with listings. For example, if you use cpvc, the piping must be held low and you have to sprig up to the sprinklers.
Travis Mack
MFP Design, LLC
www.mfpdesign.com
"Follow" us at https://www.facebook.com/pages/MFP-Design-LLC/9221...
RE: Design ideas for a NFPA 13 Residential Occupancy