Just my thoughts! I do think you need the heads in the dormers, because a
fire could burn out of control there, and thru the roof and spread across
the asphalt shingles, to involve the entire roof structure. Many times these
dormers are attic ventilation feature's and would spread the fire outside of
the structure very easily.
The Central Animated Attic Sprinkler presentation I've seen shows the water
at the underside of the roof decking/plywood. I believe that in this
application the water spray's down the underside of the plywood roof deck,
and then falls to the ceiling framing below. Wetting the underside of the
plywood and trusses/joist, cooling the hot products of combustion as they
rise up the roof slope, to control the spread of the fire.
(I hear that the same guy's that make this animation, are now working on
Srek 6, "Winonna's revenge")
Thom McMahon
Firetech, Inc.
2560 Copper Ridge Dr
Steamboat Springs, CO 80488-2136
Tel: 970-879-7952
Fax: 970-879-7926
----- Original Message -----
From: "Chris Cahill" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Tuesday, May 22, 2007 12:18 PM
Subject: Attic applications
This is a theoretical question based on a real situation and an odd idea I
had this morning. Got a single ridge line, wood attic, less than 60' wide,
no hips. A perfect application for attic heads. There are very small
dormers off the main attic. The ridge of the dormers is only ½ as high as
the main ridge. The attic heads will easily cover the floor space under the
dormer. Assuming the roof sheathing is mostly left off the area under the
dormer do I really need heads near the peak of the dormer? Now if the
sheathing of the main roof runs fully under the dormer to the eave then of
course I need to cover the concealed space of the dormer.
Isn't the goal of sprinkler installation to cover the floor area with spray
while being conscious of activation time, 8.1.1 (3) of the '07? With that
premise the floor is covered as well as if the dormers didn't exist, check,
got that part covered. The activation time might be impacted but IMHO not
significantly. I'm not a master of the computer models to handle this and
don't have any spare matches to run a test.
Looking at the cut sheets really doesn't get me too far. B-6 bottom diagram
is the best picture of what I'm trying to describe. Detail B-5 and B-6 are
the closest. B-6 has the note dormer built on top of roof or sheathing
which kind of implies heads are needed. But from the title of the section
this would apply to situations where the sheathing is complete.
What if the dormer was a bit bigger like when they bump out the plane of the
roof slope adding a 3-4 ridge running perpendicular to the main ridge but
below the main ridge? Sorry I don't know all my roof terms.
Chris Cahill, P.E.
Fire Protection Engineer
Sentry Fire Protection, Inc.
763-658-4483
763-658-4921 fax
Email: <mailto:[EMAIL PROTECTED]> [EMAIL PROTECTED]
Mail: P.O. Box 69
Waverly, MN 55390
Location: 4439 Hwy 12 SW
Waverly, MN 55390
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