Sorry for the confusion - 13 R system installed under the 2007 13 R
4.3 Basic Requirements.
4.3.1 The requirements for spacing, location, and position of
sprinklers shall be based on the following principles:
(1) Sprinklers shall be installed throughout the premises.
(2) Sprinklers shall be located so as not to exceed maximum
protection area per sprinkler.
(3) Sprinklers shall be positioned and located so as to provide
satisfactory performance with respect to activation time
and distribution.
(4) Sprinklers shall be permitted to be omitted from areas
specifically allowed by this standard (see Section 6.9).
(5) When sprinklers are specifically tested and test results demonstrate
that deviations from clearance requirements to
structural members do not impair the ability of the sprinkler
to control or suppress a fire, their positioning and locating
in accordance with the test results shall be permitted.
(6) Clearance between sprinklers and ceilings exceeding the
maximums specified in this standard shall be permitted,
provided that tests or calculations demonstrate comparable
sensitivity and performance of the sprinklers to
those installed in conformance with these sections.
Exception # 4 pushes you to section 6.9
6.9 Location of Sprinklers.
6.9.1 Sprinklers shall be installed in all areas except where
omission is permitted by 6.9.2 through 6.9.7.
6.9.2* Sprinklers shall not be required in bathrooms where
the bathroom area does not exceed 55 ft2 (5.1 m2).
6.9.3 Except where specified in 6.9.4, sprinklers shall not be
required in clothes closets, linen closets, and pantries within
dwelling units that meet all of the following conditions:
(1) The area of the space does not exceed 24 ft2 (2.2 m2).
(2) The least dimension does not exceed 3 ft (0.91 m).
(3) The walls and ceilings are surfaced with noncombustible
or limited-combustible materials as defined by NFPA 220,
Standard on Types of Building Construction.
6.9.4 Sprinklers shall be installed in any closet used for heating
and air-conditioning equipment.
6.9.5 Sprinklers shall not be required in any porches, balconies,
corridors, and stairs that are open and attached.
6.9.6* Sprinklers shall not be required in attics, penthouse
equipment rooms, elevator machine rooms, concealed spaces
dedicated exclusively to and containing only dwelling unit
ventilation equipment, crawl spaces, floor/ceiling spaces,
noncombustible elevator shafts where the elevator cars comply
with ANSI A17.1, Safety Code for Elevators and Escalators, and
other concealed spaces that are not used or intended for living
purposes or storage and do not contain fuel-fired equipment.
6.9.7 Sprinklers shall not be required in closets on exterior
balconies, regardless of size, as long as there are no doors or
unprotected penetrations from the closet directly into the
dwelling unit.
and item 6.9.6 seems to indicate that it not required since the utility closet (riser room) since it is not intended for living space and not used for storage.
or you can use:
6.9.7 Sprinklers shall not be required in closets on exterior
balconies, regardless of size, as long as there are no doors or
unprotected penetrations from the closet directly into the
dwelling unit.
The only return on a pdf searchable document for 13 R for riser is protection from mechanical damage -
What Says thee.....