Use NFPA 13D for 2 Apartments Above a Garage?

1/31/2025

I have a project with two existing 900 sqft apartments above a non-sprinklered marine repair garage. Only the apartments are required to be sprinklered.

Can I sprinkler the two apartments per NFPA 13D, or do I have to do per NFPA 13R?

I know the definition of dwellings says no more than two dwelling units in 13D. Thank you.

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5 Comments

Anthony L. Crispo

1/31/2025 06:52:37 am

I think you'll be at full 13 due to the repair garage underneath the apartments unless there is an IBC 510 exception. Get a full code path from the architect if there is one on your project.

Dan Wilder

1/31/2025 07:40:13 am

I'm not even sure of the code path that would allow this partial sprinkler installation in the first place....?

The appendix of 13D 1.1 states the below info which leads me to think that 13R would be a better application...:

This standard is appropriate for protection against fire hazards only in one- and two-family dwellings and manufactured homes. A one- and/or two-family dwelling that is used as a rental property could still be appropriate to be protected with a system installed in accordance with NFPA 13D. Residential portions of any other type of building occupancy or within mixed occupancies should be protected with sprinklers in accordance with NFPA 13 or NFPA 13R. Nonresidential portions of such buildings should be protected in accordance with NFPA 13 or NFPA 13R as appropriate for areas outside the dwelling unit.

Chad

1/31/2025 11:49:48 am

With the proper fire separation you could have a partial sprinklered building, correct?

Assuming this is all existing and now being caught

I agree it would be a full 13, although I have also seen some AHJ's allow 13D for one and two families above retail, as a compromise to get the resi sprinklered (with proper fire separation)

Brett

1/31/2025 12:15:30 pm

If the IBC applies then generally, yes, if buildings are separated by fire walls or in some cases if occupancies are separated by fire barriers and/or horizontal assemblies then you can partially sprinkler areas. In the case of a residential occupancy, if sprinklers are required then they are required for the entire building (903.2.8). Horizontal building separations can be done in accordance with IBC section 510, but the lower building is required to be sprinklered (510.2(6)).

It's hard to say what's required for the project that's being asked without knowing what the applicable codes are. Ignoring the part about the lower level not being sprinklered (I don't know of a code path that allows this unless the upper level sprinkler system is voluntary), then if the occupancies are properly separated then the upper level sprinkler system could certainly be 13R or 13D. It's impossible to say if it should be 13R or 13D without knowing the occupancy classification.

Jack G

1/31/2025 10:55:43 am

A marine repair garage is classified as OH-2, unless there is quantities of flammable liquids or cleaning solvents ( 5 liters or less. ) fuel in fuel tanks are permitted but not storage tanks ( becomes NFPA 30 domain), otherwise the garage becomes an H occupancy. Unless above conditions are met ( no tank storage over 5 liters)
That being said, if the garage is not required to be protected than the 2 occupancies must be separated with a 2 hour fire separation.
( making them in essence 2 buildings) .
Depending on how the building is constructed ( construction type )
the 1800 sq feet of apartments above because if the mixed use the apartment becomes an nfpa13 system. See Meyer Fire 13, 13r, 13 d, cheat sheet.

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Use NFPA 13D for 2 Apartments Above a Garage?

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