Here is the 2015 Commentary:
[F] 903.2.7 Group M. An automatic sprinkler system shall
be provided throughout buildings containing a Group M
occupancy where one of the following conditions exists:
1. A Group M fire area exceeds 12,000 square feet (1115
m2).
2. A Group M fire area is located more than three stories
above grade plane.
3. The combined area of all Group M fire areas on all
floors, including any mezzanines, exceeds 24,000
square feet (2230 m2).
4. A Group M occupancy used for the display and sale of
upholstered furniture or mattresses exceeds 5,000
square feet (464 m2).
The sprinkler threshold requirements for Group M
occupancies are identical to those of Group F-1 and
S-1 occupancies (see commentary, Section 903.2.4).
The one exception is that Group M occupancies are
provided with an increased area for display of upholstered
furniture and mattresses of 5,000 square feet
(464 m2) versus 2,500 square feet (232 m2) required
for Group F-1 and S-1 occupancies. As noted in the
commentary for Group F-1 occupancies, upholstered
furniture and mattresses have the potential for rapidly
growing and high-heat-release fires. This hazard is
increased substantially when there are numerous
upholstered furniture items or mattresses on display.
Such fires put the occupants and emergency
responders at risk. This requirement exists regardless
of whether the upholstered furniture has passed
any fire-retardant tests.
The code does not specifically address what constitutes
upholstered furniture, but by simple dictionary
definition, upholstered furniture has seats covered
with padding, springs, webbing and fabric or leather
covers. The code does not make any distinction
between levels of padding and upholstery provided
on furniture, which was intentional. The proponent’s
reason statement for code change F135-07/08
stated, in part, “the American Home Furnishings Alliance
(AHFA) and the National Home Furnishings
Association (NHFA) have examined proposals for
exempting vendors of certain constructions of furniture
and concluded that such exemptions would be
impractical for local code officials to enforce. This is
the case because the internal construction of furniture
cannot be established reliably without deconstructing
it.”
Note that, as with Group F-1 occupancies, the criteria
is written such that any Group M occupancy, not
the fire area, over 5,000 square feet (464 m2) used for
the display and sale of upholstered furniture and mattresses
shall be sprinklered throughout. This is
regardless of the quantity of upholstered furniture and
mattresses actually available for purchase. The reason
these requirements were placed into the code
and the IFC was based on a large fire in Charleston,
South Carolina that killed nine fire fighters. The facility
was a combination furniture showroom and associated
storage area. The building did not provide an
automatic sprinkler system. See the commentary to
Section 903.2.9 for discussion of a formal interpretation
dealing with Group S-1 occupancies and applicability
to the code and the IFC.
Automatic sprinkler systems for mercantile occupancies
are typically designed for an Ordinary Hazard
Group 2 classification in accordance with NFPA
13. If high-piled storage (see Section 903.2.7.1) is
anticipated, additional levels of fire protection may be
required. Also, some merchandise in mercantile
occupancies, such as aerosols, rubber tires, paints
and certain plastic commodities, even at limited storage
heights, are considered beyond the standard
Class I through IV commodity classification assumed
for mercantile occupancies in NFPA 13 and may warrant
additional fire protection.