Sprinklers Req'd for 13R Non-combustible Porch?

6/28/2024

All - talk me off the ledge, I have overanalyzed the requirement of dry sidewalls on porches and now I can't sleep until I get this answered:

Initial design of an apartment complex (3 story) called for an NFPA 13 (2019 edition) fire sprinkler system. The apartment complex will be covered in a cementitious siding and trim (non-combustible).

Under NFPA 13 Section 8.15.7.2, sprinklers may be omitted from porches constructed with non-combustible or limited combustible materials in accordance with NFPA 703's requirements concerning non- and limited-combustible materials. The cementitious lap siding and trim exceeds the non-combustible requirements of NFPA 703.

The plot thickens - the apartment design was changed to incorporate an NFPA 13R (2019 edition) fire sprinkler system instead of NFPA 13. Under NFPA 13R Section 6.6.5.1 Where a roof or deck is provide 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.

The building construction Type is V-B but the porches are constructed of non-combustible materials - and this configuration/condition is not addressed in NFPA 13R.

NFPA 13R Section 6.6.8 "All situations regarding sprinkler location and position that are not directly discussed in NFPA 13R shall be in accordance with NFPA 13. NFPA 13R does not address exterior porches constructed of non-combustible materials - since this situation is not addressed directly in NFPA 13R it is addressed in NFPA 13 which is detailed above (NFPA 13 Section 8.15.7.2).

So based on the above - are sprinklers required on non-combustible porches in NFPA 13R systems?

In addition, if sprinklers are required on non-combustible porches in an NFPA 13R system, why would NFPA 13 allow them to be excluded - as NFPA 13 should be the more "conservative" standard?

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10 Comments

Brett

6/28/2024 06:31:40 am

13R doesn't delve into combustible vs noncombustible finishes in this case. If it's type V construction, then the patios get sprinklered. Additionally, if the IBC applies, see section 903.3.1.2.1 which mandates the same requirement and gives some additional requirements regarding the placement of the sidewall sprinkler deflectors.

Greg

6/28/2024 08:38:13 am

VB or not to VB, pondering the role of sprinklers in wood construction...I'm observing a great deal of VB construction in my area, where four and five stories are being built atop a commercial ground floor level. The stories that are VB are seemingly completely reliant on sprinkler performance within the interior spaces. I suppose there is draft block but alas, more wood. My sentiment is this, sprinklers can control and, in some instances, extinguish but is there too much faith in the successful initiation and water flow for the building's lifespan. To the question posed, I believe sprinklers are beneficial for patios and balconies, but does VB fall short in the situations where builders are achieving new heights?

Todd E Wyatt

6/28/2024 08:38:58 am

The scoping Code (e.g. IBC-2021) identifies WHERE an automatic sprinkler system (ASPS) is required based on the Occupancy Classification(s) (OC) assigned to the building.

The referenced ASPS standard (e.g. NFPA 13-2019 or NFPA 13R-2019) prescribes HOW a building’s ASPS is to be designed, installed, inspected, and maintained.

IBC-2021 does not reference “porches” but it does reference “balconies and decks” as it pertains to NFPA 13R (but not NFPA 13) :

Chapter 9 Fire Protection and Life Safety Systems
903.3 Installation Requirements
903.3.1 Standards
903.3.1.2 NFPA 13R Sprinkler Systems
903.3.1.2.1 Balconies and Decks
Sprinkler protection shall be provided for exterior balconies, decks and ground floor patios of dwelling units and sleeping units where either of the following conditions exists:
1. The building is of Type V construction, provided that there is a roof or deck above.
2. Exterior balconies, decks and ground floor patios of dwelling units and sleeping units are constructed in accordance with Section 705.2.3.1, Exception 3.
Sidewall sprinklers that are used to protect such areas shall be permitted to be located such that their deflectors are within 1 inch (25 mm) to 6 inches (152 mm) below the structural members and a maximum distance of 14 inches (356 mm) below the deck of the exterior balconies and decks that are constructed of open wood joist construction.

While your question did not identify the Occupancy Classification(s) (OC) assigned to the building, since NFPA 13 and NFPA 13R were both used, it implies that the OC is Group R - Residential meeting ALL (3) conditions :

Chapter 9 Fire Protection and Life Safety Systems
903.3 Installation Requirements
903.3.1 Standards
903.3.1.2 NFPA 13R Sprinkler Systems
Automatic sprinkler systems in Group R occupancies shall be permitted to be installed throughout in accordance with NFPA 13R where the Group R occupancy meets all of the following conditions:
1. Four stories or fewer above grade plane.
2. The floor level of the highest story is 30 feet (9144 mm) or less above the lowest level of fire department vehicle access.
3. The floor level of the lowest story is 30 feet (9144 mm) or less below the lowest level of fire department vehicle access.
The number of stories of Group R occupancies constructed in accordance with Sections 510.2 and 510.4 shall be measured from grade plane.

If the building meets ALL of these conditions, then NFPA 13R is “permitted” to be used … it is not “required” to be used however.

If NFPA 13 is to be used, only the below (6) + (1) Exempt Locations do not require an ASPS … “balconies and decks” are not listed here.

Chapter 9 Fire Protection and Life Safety Systems
903.3 Installation Requirements
903.3.1 Standards
903.3.1.1 NFPA 13 Sprinkler Systems
Where the provisions of this code require that a building or portion thereof be equipped throughout with an automatic sprinkler system in accordance with this section, sprinklers shall be installed throughout in accordance with NFPA 13 except as provided in Sections 903.3.1.1.1 and 903.3.1.1.2.
903.3.1.1.1 Exempt Locations
Automatic sprinklers shall not be required in the following rooms or areas where such rooms or areas are protected with an approved automatic fire detection system in accordance with Section 907.2 that will respond to visible or invisible particles of combustion. Sprinklers shall not be omitted from a room merely because it is damp, of fire-resistance-rated construction or contains electrical equipment.
1. A room where the application of water, or flame and water, constitutes a serious life or fire hazard.
2. A room or space where sprinklers are considered undesirable because of the nature of the contents, where approved by the fire code official.
3. Generator and transformer rooms separated from the remainder of the building by walls and floor/ceiling or roof/ceiling assemblies having a fire-resistance rating of not less than 2 hours.
4. Rooms or areas that are of noncombustible construction with wholly noncombustible contents.
5. Fire service access elevator machine rooms and machinery spaces.
6. Machine rooms, machinery spaces, control rooms and control spaces associated with occupant evacuation elevators designed in accordance with Section 3008.
903.3.1.1.2 Bathrooms
In Group R occupancies sprinklers shall not be required in bathrooms that do not exceed 55 square feet (5 m2) in area and are located within individual dwelling units or sleeping units, provided that walls and ceilings, including the walls and ceilings behind a shower enclosure or tub, are of noncombustible or limited-combustible materials with a 15-minute thermal barrier rating.

6/28/2024 08:46:35 am

I missed the reference to "apartment" so the OC would be Group R-2 :

IBC-2021
Chapter 3 Occupancy Classification and Use
310.1 Residential Group R
310.3 Residential Group R-2
Residential Group R-2 occupancies containing sleeping units or more than two dwelling units where the occupants are primarily permanent in nature, including:
Apartment houses

Chapter 9 Fire Protection and Life Safety Systems, Section 903 Automatic Sprinkler Systems does not include references to "R-2", just to "Group R".

6/28/2024 08:51:56 am

Here’s “705.2.3.1” as referenced by 903.3.1.2.1 :

IBC-2021
Chapter 7 Fire and Smoke Protection Features
Section 705 Exterior Walls
705.2 Projections
705.2.3 Projection Protection
705.2.3.1 Balconies and Similar Projections
Balconies and similar projections of combustible construction other than fire-retardant-treated wood shall be fire-resistance rated where required by Table 601 for floor construction or shall be of heavy timber construction in accordance with Section 2304.11. The aggregate length of the projections shall not exceed 50 percent of the building's perimeter on each floor.
Exceptions:
1. On buildings of Types I and II construction, three stories or less above grade plane, fire-retardant-treated wood shall be permitted for balconies, porches, decks and exterior stairways not used as required exits.
2. Untreated wood and plastic composites that comply with ASTM D7032 and Section 2612 are permitted for pickets, rails and similar guard components that are limited to 42 inches (1067 mm) in height.
3. Balconies and similar projections on buildings of Types III, IV and V construction shall be permitted to be of Type V construction and shall not be required to have a fire-resistance rating where sprinkler protection is extended to these areas.
4. Where sprinkler protection is extended to the balcony areas, the aggregate length of the balcony on each floor shall not be limited.

Pete H

6/28/2024 09:10:21 am

Unfortunately I'm in the camp of "13R doesn't address the change of construction of the noncombustible porch, just the building construction." so I'd just put the dryflex sidewalls in and charge the client an extra for changing the construction type from 13 to 13R.

That stated, you make a decent argument about this being addressed in 13 and not 13R and 13R Section 6.6.8. So if you want to really go "over and above", reach out to the AHJ that you'll be submitting the plans to, tell them the grey area you found and the interpretation you'd like to use (that you can do the porches as per 13 where they're directly addressed but not addressed in 13R as per 6.6.8.).

Worst they can do is say no, but your code reading has made it enough of a grey area that I'd say it is their call.

Jack G

6/28/2024 09:14:34 am

Agree on the most part however
Please review the Meyer fire cheat sheet in the tool box for NFPA13 r where it linexplisively maps out where sprinklers are required for 13r.
The apartments would require that protection would be required under the common walkways and the egress.

Jesse

6/28/2024 10:46:27 am

13R doesn't have the non-combustible verbiage that 13 does. Since the building is Type V, looks like you need to protect the porches.

Jon Nisja

6/28/2024 09:50:43 pm

Remember that in Type V construction, the porches, decks and balconies are often supported or cantilevered from the floor assembly. If the building has an NFPA 13R sprinkler system, this could mean that the deck or balcony (or porch, as mentioned in the original post) is being supported by structural members with no fire protection since NFPA 13R has no requirement for interstitial or concealed space protection. This may be the reason for differing requirements and exemptions between NFPA 13 and 13R.

Patrick Nelligan

7/1/2024 09:51:24 am

OP, the one section in NFPA 13, 2016, that several AHJs have negated the previous sections of 8.15.7 in residential construction is 8.15.7.5 Sprinklers shall be installed under exterior projections greater than 2 ft (600 mm) wide over areas where combustibles are stored. (I.E., Barbeques) They always ask if there is the potential of a BBQ. If yes, then you shall sprinkler the balconies. Do not know if that helps, just relaying experience I have had with several west coast AHJs.

Sprinklers Req'd for 13R Non-combustible Porch?

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