The only point you didn't take into consideration is the 3000sf has no
correlation to property protection. As I understand it, it was a WAG years
ago before the current emphasis on testing and data to make changes. There
is no experience or testing that I have heard of that justifies this
requirement. Seems to me there was a time in the mid 90's where some
lobbied to take it away. Of course they didn't have data or testing to show
it served little value either so it remains.
Let's face it for the most part we are talking about fire above a ceiling
above the sprinklers, right. Sprinklers don't spray up very well especially
through ceilings these days.
I was involved in a fire of this nature in a sprinklered building. My notes
from the day:
Occupant cutting away old pipes with torch. Noted a small hot
spot/fire in the fiber board ceiling. Occupant sprayed water on area.
14 hours later passer by noted smoke coming from roof. Fire all above
ceiling in joist space where no sprinklers are required nor present.
About 10 heads operated through the course of the fire. 4 in the
immediate area of the origin. The others in a sporadic fashion.
Sprinkler monitoring had been turned off for quite some time.
To gain control of the fire we had to shut the system off. It was rather
problematic to work through the ceiling while in the down pour of sprinkler
water. Granted this was a poor example in that there was not much to burn
on the floor. But either way there wasn't much drop down even had there
been stuff on the floor. As I saw it the only value of the sprinklers was
heat detector with water (vs. electrons) as the signal transfer medium based
fire alarm system. Go look for that in NFPA 72. I'm convinced had the
monitoring been present even with combustibles below this would have been a
1 or 2 head fire and we'd still have shut off the sprinklers to get at it.
Chris Cahill, P.E.
Fire Protection Engineer
Sentry Fire Protection, Inc.
763-658-4483
763-658-4921 fax
Email: [EMAIL PROTECTED]
Mail: P.O. Box 69
Waverly, MN 55390
Location: 4439 Hwy 12 SW
Waverly, MN 55390
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Ed Kramer
Sent: Friday, April 18, 2008 11:30 AM
To: [email protected]
Subject: RE: NFPA 13 Building with residential heads
I'll chime in with my opinion.
Does 13 REQUIRE the 3,000 sf DA? The section that requires the 3,000 sf DA
[11.2.3.1.4(3)] is part of section 11.2 "Occupancy Hazard Fire Control
Approach". Residential sprinkler design is a separate section (11.3.1) and
is not subject to the requirements of section 11.2.
SHOULD 13 require the 3,000 sf DA? The underlying premise of 13 is property
protection. Allowing residential sprinklers to be used in dwelling units
adds to the life safety aspect of the system, but its' still primarily a
property protection system. For that reason, I can't believe it's the
INTENT of 13 to not require the 3,000 sf DA. Property protection is
property protection, whether the sprinkler used is a SSP or residential.
That's the exact reason why a .10 gpm/sf density is required when using
residential sprinklers. So even though I don't think the 3,000 sf DA is
required, I think it should be.
Exit soapbox, stage right.
Ed Kramer
Littleton, CO
> NFPA 13 (07ed)
>
> I am designing a sprinkler system for a Hotel that falls under NFPA 13.
> The floors containing the residential units have a combustible concealed
> space
> that does not require sprinklers (8.15.1.2.6) but does not qualify for
> the 3000 sq ft
> exemption of 11.2.3.1.4 (4) for unsprinklered combustible concealed
> spaces.
> If I am using residential sprinklers, are they exempt from this rule
> because they are
> a specific application sprinkler and not an area/density or room design
> method?
> Thanks,
> Dewayne
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