NFPA 13D permits the omission of fire sprinklers in certain locations of a home.

Sprinklers shall not be required in bathrooms of 55 square feet or less.
Combustible fuel loading in most small bathrooms typically is low.

Sprinklers shall not be required in garages, open attached porches, carports, and similar structures.
Many are surprised to learn that NFPA 13D does not require sprinklers in garages. But, in fact, few deadly fires start in garages. A simple cost-benefit analysis can illustrate that the extra expense of placing sprinklers in garages does not provide an equal balance of protection due to the fact that most garages are not heated and the sprinkler system would need to be a dry system or an antifreeze system in many geographic regions. This cost-benefit analysis and the fact that most residential building codes require a one-hour fire resistance rating for the walls separating the garage and the remainder of the home led to this omission. While NFPA 13D does not require garages to be sprinklered, some authorities having jurisdiction requiring the installation in these areas.

Sprinklers shall not be required in clothes closets, linen closets, and pantries that meet all of the following conditions:
(1) The area of the space does not exceed 24 square feet.
(2) The walls and ceilings are surfaced with noncombustible or limited-combustible materials.

Small closets are usually impractical places to install sprinklers because of their relatively small size. When mechanical equipment or laundry machines are placed in the closet, the closet is no longer considered a clothes closet, linen closet, or pantry, so this exception is no longer valid and sprinklers must be installed.

Sprinklers shall not be required in attics with or without storage, penthouse equipment rooms, elevator machine rooms, concealed spaces dedicated exclusively to and containing only dwelling unit ventilation equipment, floor/ceiling spaces, elevator shafts, crawl spaces, and other concealed spaces that are not used or intended for living purposes.

The following are examples of attics that would typically be considered intended for living purposes and would need sprinkler protection:
• Attics for which a set of walk-up stairs has been constructed
• Attics that have been enclosed and are heated or air conditioned, even if not finished
• Attics that have been provided electrical, lighting, and heating or air conditioning

Typically, attics with only access hatches would not be considered as intended for living purposes,even if used for storage.

Sprinklers shall not be required in covered, unheated projections of the building at entrances/exits as long as the dwelling unit has another means of egress. 

Authorities having jurisdiction have allowed the omission of sprinklers in the following types of spaces:
• Mudrooms: unheated areas where shoes and coats are taken off and stored
• Bulkheads: areas leading from below grade basements to the exterior grade with an intervening door at the basement level

Sprinklers shall not be required for ceiling pockets that meet the following conditions:
(1) The total volume of all unprotected ceiling pockets in a compartment does not exceed 100 cubic feet.
(2) The entire floor under the unprotected ceiling pocket is protected by sprinklers at the lower ceiling elevation.
(3) The interior finish of the unprotected ceiling pocket excluding decorative treatments is noncombustible or limited-combustible material.
(4) Skylights not exceeding 32 square feet shall be permitted to have a plastic cover.

Sprinklers shall not be required in closets in garages and exterior closets (regardless of size) located on exterior balconies, exterior breezeways/corridors, or accessed from outdoors where the closet does not have doors or unprotected penetrations directly into the dwelling unit.

This provision, is consistent with the opinion that sprinklers should not be required in spaces subject to cold temperatures or spaces where statistics do not indicate a significant occurrence of fire or fatality. The assumption is that a barrier exists between the exterior closet and the dwelling unit and that openings and penetrations between the two are appropriately protected.

Reference: NFPA 13D, Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes