The occupancies that permit spiral stairs are asfollows:
1.Assembly occupancies (12.2.2.3.2.2, 13.2.2.3.2.2)
2.Detention and correctional occupancies (22.2.2.3.2,23.2.2.3.2)
3.One- and two-family dwellings (24.2.5.5)
4.Apartment buildings (30.2.2.3.3, 31.2.2.3.3)
5.Mercantile occupancies (36.2.2.3.2, 37.2.2.3.2)
6.Business occupancies (38.2.2.3.2, 39.2.2.3.2)
7.Industrial occupancies (40.2.2.3.2)
8.Storage occupancies (42.2.2.3.2)
| OCCUPANCY TYPE (new building)
|
CODE REF. |
SPIRAL STAIRS
|
| AMBULATORY |
(chapter 20) |
Not Permitted? |
| ASSEMBLY |
(12.2.2.3.2.2 and 7.2.2.2.3) |
Permitted in Lighting and access catwalks, galleries and gridlines |
| BUSINESS |
(38.2.2.3.2 and 7.2.2.2.3) |
Permitted |
| HEALTHCARE |
(chapter 18) |
Not Permitted? |
| EDUCATIONAL |
(chapter 14) |
Not Permitted? |
| ONE & TWO FAMILY DWELLINGS
|
(chapter 24) |
Not Permitted? |
| HOTELS AND DORMITORIES |
(chapter 28) |
Not Permitted? |
| APARTMENTS |
(chapter 30) |
Not Permitted? |
| MERCANTILE |
(36.2.2.3.2 and 7.2.2.2.3) |
Permitted |
| STORAGE |
(42.2.2.3.2 and 7.2.2.2.3) |
Permitted |
| INDUSTRIAL
|
(40.2.2.3.2 and 7.2.2.2.3) |
Permitted |
Notes:
- Code Reference used is NFPA-101 2012 edition unless otherwise noted.
- These information is not complete and intended to be used as quick references only, always refer to NFPA or your local codes for complete information.
7.2.2.2.3 Spiral Stairs.
7.2.2.2.3.1 Where specifically permitted for individual occupancies by Chapters 11 through 43, spiral stairs shall be permitted as a component in a means of egress in accordance with 7.2.2.2.3.2 through 7.2.2.2.3.4.
7.2.2.2.3.2 Spiral stairs shall be permitted, provided that the following criteria are met:
- (1) Riser heights shall not exceed 7 in. (180 mm).
- (2) The stairway shall have a tread depth of not less than 11in. (280 mm) for a portion of the stairway width sufficient to provide egress capacity for the occupant load served in accordance with 7.3.3.1.
- (3) At the outer side of the stairway, an additional 101/2in.(265 mm) of width shall be provided clear to the other handrail, and this width shall not be included as part of the required egress capacity.
- (4) Handrails complying with 7.2.2.4 shall be provided on both sides of the spiral stairway.
- (5) The inner handrail shall be located within 24 in. (610mm), measured horizontally, of the point where a tread depth of not less than 11 in. (280 mm) is provided.
- (6) The turn of the stairway shall be such that the outer handrail is at the right side of descending users.
7.2.2.2.3.3 Where the occupant load served does not exceed three, spiral stairs shall be permitted, provided that the following criteria are met:
(1) The clear width of the stairs shall be not less than 26 in.(660 mm).
(2) The height of risers shall not exceed 91/2in. (240 mm).
(3) The headroom shall be not less than 6 ft 6 in. (1980 mm).
(4) Treads shall have a depth not less than 71/2in. (190 mm)at a point 12 in. (305 mm) from the narrower edge.
(5) All treads shall be identical.
(6) Handrails shall be provided on both sides of the stairway.
7.2.2.2.3.4 Where the occupant load served does not exceed five, existing spiral stairs shall be permitted, provided that the requirements of 7.2.2.2.3.3(1) through (5) are met.
Spiral stairs can be used only where expressly permit-ted by the appropriate occupancy chapter. Some occu-pancy chapters establish additional limitations. For example, in assembly occupancies, spiral stairs arepermitted only from lighting and access catwalks, gal-leries, and gridirons. In apartment buildings, spiralstairs are permitted only within a dwelling unit, not within the common spaces and egress paths servingmultiple dwelling units.
The occupancies that permit spiral stairs are as follows:
1.Assembly occupancies (12.2.2.3.2.2, 13.2.2.3.2.2)
2.Detention and correctional occupancies (22.2.2.3.2,23.2.2.3.2)
3.One- and two-family dwellings (24.2.5.5)
4.Apartment buildings (30.2.2.3.3, 31.2.2.3.3)
5.Mercantile occupancies (36.2.2.3.2, 37.2.2.3.2)
6.Business occupancies (38.2.2.3.2, 39.2.2.3.2)
7.Industrial occupancies (40.2.2.3.2)
8.Storage occupancies (42.2.2.3.2)
The requirement of 7.2.2.2.3.2 is significant in that it in-cludes a spiral stair geometry that can be used withouta prespecified maximum occupant limit. The numberof occupants permitted to use a spiral stair depends onhow much egress width is provided. The term egresswidthhas a specific meaning in this instance. It ex-cludes the narrow part of the tapered tread that hasless than 11 in. (280 mm) of tread depth. It also ex-cludes the outer 101/2 in. (265 mm) of tread width. Notethat handrails are required at both sides. Also, the turnof the stairway must be such that the outer handrail isavailable to descending users at their right side. Thesecriteria are depicted in Exhibit 7.30. An additional cri-terion is that the riser height not exceed 7 in. (180 mm),as is required for traditional stairs in accordance withTable 7.2.2.2.1.1(a).
The requirement of 7.2.2.2.3.3 retains the dimen-sional criteria for spiral stairs from earlier editions ofthe Codebut changes the maximum number of occu- pants served by the stair from five to three and requiresthat handrails be provided at both sides of the stair.
The requirement of 7.2.2.2.3.4 applies to existingspiral stairs. The traditional five-person limit and therequirement that a handrail be at the open side havebeen retained.
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Exhibit 7.30Spiral stair tread dimensional criteriareflecting the requirements of 7.2.2.2.3.2.