from NFPA "13R" 2013 edition
6.6.5* Except as provided for in 6.6.5.1, sprinklers shall not be required in any porches, balconies, corridors, carports, porte cocheres, and stairs that are open and attached.
6.6.5.1 Where a roof or deck is provided above, sprinklers shall be installed to protect attached exterior balconies, attached exterior decks, and ground floor patios serving dwelling units in buildings of Construction Type V.
6.6.5.1.1 Where sidewall sprinklers are installed beneath decks or balconies constructed with open wood joists, sprinklers shall be permitted to be installed with deflectors not less than 1 in. (25 mm) or more than 6 in. (152 mm) below the structural members, provided that the deflector is not more than 14 in. (356 mm) below the underside surface of the deck.
FROM NFPA "13" 2013 edition
8.15.7* Exterior Projections.
8.15.7.1 Unless the requirements of 8.15.7.2, 8.15.7.3, or 8.15.7.4 are met, sprinklers shall be installed under exterior projections exceeding 4 ft (1.2 m) in width.
8.15.7.2* Sprinklers shall be permitted to be omitted where the exterior projections are constructed with materials that are noncombustible, limited-combustible, or fire retardant–treated wood as defined in NFPA 703.
8.15.7.3 Sprinklers shall be permitted to be omitted from below the exterior projections of combustible construction, provided the exposed finish material on the exterior projections are noncombustible, limited-combustible, or fire retardant–treated wood as defined in NFPA 703, and the exterior projections contain only sprinklered concealed spaces or any of the following unsprinklered combustible concealed spaces:
(1)
Combustible concealed spaces filled entirely with noncombustible insulation
(2)
Light or ordinary hazard occupancies where noncombustible or limited-combustible ceilings are directly attached to the bottom of solid wood joists so as to create enclosed joist spaces 160 ft3 (4.5 m3) or less in volume, including space below insulation that is laid directly on top or within the ceiling joists in an otherwise sprinklered attic [see 11.2.3.1.4(4)(d)]
(3)
Concealed spaces over isolated small exterior projections not exceeding 55 ft2 (5.1 m2) in area
8.15.7.4 Sprinklers shall be permitted to be omitted from exterior exit corridors when the exterior walls of the corridor are at least 50 percent open and when the corridor is entirely of noncombustible construction.
8.15.7.5* Sprinklers shall be installed under exterior projections greater than 2 ft (0.6 m) wide over areas where combustibles are stored.