Unnoccupied Spaces

[admiralArchArch]

We are proposing a space underneath 5 stories of IIIB residential construction. Due to grades and cost of backfilling, we are proposing to basically create a building on "stilts" but surrounded with walls (a crawl space if you will). The next story up (level 2) will connect to the building at the level. It's rather confusing but look at my previous post to see the layout.

Now, we will consider this a story and provide a 3-hr horizontal separation of IA construction. However, we want to consider this space unoccupied and believe we can omit sprinklers in this space 903.3.1.1.1 #4. A minimal door would be provided for maintenance only.

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.

4. Rooms or areas that are of noncombustible construction with wholly noncombustible contents.

Do we have grounds to omit sprinklers based on that?

 

[Yankee Chronicler]

Is it a crawlspace, or a story? What's the height of this "unoccupied" space?

 

[admiralArchArch]

Is it a crawlspace, or a story? What's the height of this "unoccupied" space?

The height of the space is about 18 ft to the story above. Per IBC definition it is story since the floor above is floor above is more than 6' above grade plane. The finish floor of this space will be anywhere from 3 ft to 10ft below adjacent grade. Crawlspace isn't defined in the IBC but I'm assuming it's not due to the height above.

 

[Yankee Chronicler]

At 18 feet high, it's a story -- a story below grade (a basement).

IBC definitions:

[BG] STORY. That portion of a building included between
the upper surface of a floor and the upper surface of the floor
or roof next above (see “Basement,” “Building height,”
“Grade plane” and “Mezzanine”). A story is measured as the
vertical distance from top to top of two successive tiers of
beams or finished floor surfaces and, for the topmost story,
from the top of the floor finish to the top of the ceiling joists
or, where there is not a ceiling, to the top of the roof rafters.

Commentary:

All levels in a building that conform to this description
are stories, including basements. A mezzanine is considered
part of the story in which it is located. See
Chapter 5 for code requirements regarding limitations
on the number of stories in a building as a function of
the type of construction.

The height of the finished floor above the grade plane doesn't define what is a story. That defines what is a story above grade and what is a basement.

 

[admiralArchArch]

At 18 feet high, it's a story -- a story below grade (a basement).

IBC definitions:



Commentary:


The height of the finished floor above the grade plane doesn't define what is a story. That defines what is a story above grade and what is a basement.

But the definition of basement is "a story that is not above grade plane". See image and the definition of a story above grade plane.

 

[mtlogcabin]

Rooms or areas are not clearly defined. Depending on the sq ft of the "area" and determining if it is a story above or below Grade Plane would aid in making a decision if exemption # 4 is applicable or not.

I believe 903.2.11.1 is more specific and the exception would not apply.

[BG] STORY. That portion of a building included between the upper surface of a floor and the upper surface of the floor or roof next above (see “Basement,” “Building height,” “Grade plane” and “Mezzanine”). A story is measured as the vertical distance from top to top of two successive tiers of beams or finished floor surfaces and, for the topmost story, from the top of the floor finish to the top of the ceiling joists or, where there is not a ceiling, to the top of the roof rafters.

[F] 903.2.11.1 Stories without openings.
An automatic sprinkler system shall be installed throughout all stories, including basements, of all buildings where the floor area exceeds 1,500 square feet (139.4 m2) and where the story does not comply with the following criteria for exterior wall openings:

[BG] GRADE PLANE. A reference plane representing the average of finished ground level adjoining the building at exterior walls. Where the finished ground level slopes away from the exterior walls, the reference plane shall be established by the lowest points within the area between the building and the lot line or, where the lot line is more than 6 feet (1829 mm) from the building, between the building and a point 6 feet (1829 mm) from the building.

 

[admiralArchArch]

Rooms or areas are not clearly defined. Depending on the sq ft of the "area" and determining if it is a story above or below Grade Plane would aid in making a decision if exemption # 4 is applicable or not.

I believe 903.2.11.1 is more specific and the exception would not apply.

[BG] STORY. That portion of a building included between the upper surface of a floor and the upper surface of the floor or roof next above (see “Basement,” “Building height,” “Grade plane” and “Mezzanine”). A story is measured as the vertical distance from top to top of two successive tiers of beams or finished floor surfaces and, for the topmost story, from the top of the floor finish to the top of the ceiling joists or, where there is not a ceiling, to the top of the roof rafters.

[F] 903.2.11.1 Stories without openings.
An automatic sprinkler system shall be installed throughout all stories, including basements, of all buildings where the floor area exceeds 1,500 square feet (139.4 m2) and where the story does not comply with the following criteria for exterior wall openings:

[BG] GRADE PLANE. A reference plane representing the average of finished ground level adjoining the building at exterior walls. Where the finished ground level slopes away from the exterior walls, the reference plane shall be established by the lowest points within the area between the building and the lot line or, where the lot line is more than 6 feet (1829 mm) from the building, between the building and a point 6 feet (1829 mm) from the building.

Ok so I read 903.2.1.1.1 but was confused by it because why wouldn't that be included somewhere in 903.3? If you go to 903.2.8 Group R, it states in accordance with 903.3. Is it because 903.2 precedes 903.3?

 

[mtlogcabin]

903.2.11​

In all occupancies other than Group U, an automatic sprinkler system shall be installed for building design or hazards in the locations set forth in Sections 903.2.11.1 through 903.2.11.6.

[F] 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.
The exempt locations in 903.3.1.1 is applicable to the NFPA 13 Standard "throughout" location requirements not the IBC areas located in 903.2.11 through 903.2.11.6

 

[Yankee Chronicler]

But the definition of basement is "a story that is not above grade plane". See image and the definition of a story above grade plane.

Yes. Your point?

It's a story. It's not above grade, so it's below grade. It's a basement story.