NFPA 13R permits sprinklers to be excluded from certain exterior open features in low-rise residential buildings. Section 6.6.5.1 establishes a specific condition under which that exclusion no longer applies, and in Type V construction, that condition is common.
Type V Construction refers to a building classification in which all structural elements, including walls, arches, floors, and roofs, are made of wood or other approved materials. It is the most common construction type used in residential building.
NFPA 13R: A Quick Review
NFPA 13R applies to sprinkler systems in low-rise residential occupancies, buildings up to four stories, not exceeding 60 feet in height above grade plane. Apartment buildings, condominiums, hotels, and motels typically fall under this standard.
What 6.6.5.1 Requires
Section 6.6.5.1 of the 2025 edition states:
Where a roof, deck, or balcony greater than 4 ft (1.2 m) wide is provided above, sprinklers shall be installed to protect attached exterior balconies, attached exterior decks, and ground floor patios directly serving dwelling units in buildings of Type V construction.
If the building is Type V construction and overhead coverage greater than 4 feet wide is present, sprinklers are required on those exterior spaces.
What Determines if NFPA 13R 6.6.5.1 Applies
Type V applies to the building, not the balcony. The construction type classification is building wide. A non-combustible balcony on a Type V wood-frame building still triggers the requirement.
Only spaces directly serving individual dwelling units. Shared exterior corridors and breezeways that serve as a means of egress fall under Section 6.6.5.2. Applying the wrong section to the wrong space is a common plan review error.
The 4-foot trigger is the width of the overhead coverage. A roof overhang less than 4 feet wide does not trigger 6.6.5.1.
The Risk 6.6.5.1 Is Designed to Address
There is a documented history of fires originating on exterior balconies in Type V buildings, traveling upward through successive unprotected levels, and breaching the attic. In many NFPA 13R buildings, the attic is not protected with sprinklers, making that fire path a serious concern. Section 6.6.5.1 exists to interrupt it.
The requirement is also reflected in two parallel provisions: IBC (2024) Section 903.3.1.2.1 and NFPA 13 (2025) Section 9.3.20.1, the latter of which was added for the first time in the 2022 edition. All three point to the same outcome for Type V construction. Designers working across these standards need to recognize the requirement regardless of which document they are working from.
Installation Requirements
When sidewall sprinklers are used to protect these areas, deflectors must be positioned 1 in. to 6 in. below structural members, with a maximum of 14 in. below the deck of exterior balconies constructed of open wood joist construction. In climates subject to freezing, dry sidewall sprinklers are typically required. Per NFPA 25, dry sprinklers have defined testing and replacement intervals, this should be documented and communicated to the building owner at project closeout.
Designing to NFPA 13R 6.6.5.1
Section 6.6.5.1 is a precise, conditional requirement with direct life safety implications. For any Type V low-rise residential project under NFPA 13R, confirming compliance at the design stage, not at inspection, is the standard of care.
