We are all working with OSHA's new Walking and Working Surfaces standards and trying to figure out how all the new design standards will apply to our workplaces and activities.  And in doing so, many of us have seen that OSHA has now "officially" endorsed the use of alternating tread stairs in 1910.25(f).  But there may be a trick in this for us.  OSHA's standard 1910.25(f) basically provides us a design spec for these types of stairs and we have to look at 1910.25(b)(8) to find any limitations on where/how they can be used.  

1910.25(b)(8) Spiral, ship, or alternating tread-type stairs are used ONLY when the employer can demonstrate that it is not feasible to provide standard stairs. (emphasis added by me)

However, that is only OSHA's limitation on where/how they can be used...

Recent editions of the International Building Code (which many states have adopted) limit alternating tread stairs in the following ways:


1009.10 Vertical rise. A flight of stairs shall not have a vertical rise greater than 12 feet (3658 mm) between floor levels or landings.


1. Aisle stairs complying with Section 1028.

2. Alternating tread devices used as a means of egress shall NOT have a rise greater than 20 feet (6096 mm) between floor levels or landings.


1009.13 Alternating tread devices. Alternating tread devices ARE LIMITED to an element of a means of egress in buildings of Groups F, H and S (see notes below) from a mezzanine NOT more than 250 square feet (23m2) in area AND which serves NOT MORE THAN five (5) occupants; in buildings of Group I-3 from a guard tower, observation station or control room not more than 250 square feet (23m2) in area and for access to unoccupied roofs.



Factory Industrial Group F occupancy includes, among others, the use of a building or structure, or a portion thereof, for assembling, disassembling, fabricating, finishing, manufacturing, packaging, repair or processing operations that are not classified as a Group H hazardous or Group S storage occupancy.

High-hazard Group H occupancy includes, among others, the use of a building or structure, or a portion thereof, that involves the manufacturing, processing, generation or storage of materials that constitute a physical or health hazard in quantities in excess of those allowed in control areas complying with Section 414, based on the maximum allowable quantity limits for control areas set forth in Tables 307.1(1) and 307.1(2). Hazardous occupancies are classified in Groups H-l, H-2, H-3, H-4 and H-5 and shall be in accordance with this section, the requirements of Section 415 and the International Fire Code. Hazardous materials stored, or used on top of roofs or canopies shall be classified as outdoor storage or use and shall comply with the International Fire Code.

Exceptions: The following shall NOT be classified as Group H, but shall be classified as the occupancy that they most nearly resemble.

1. Buildings and structures occupied for the application of flammable finishes, provided that such buildings or areas conform to the requirements of Section 416 and the International Fire Code.

2. Wholesale and retail sales and storage of flammable and combustible liquids in mercantile occupancies conforming to the International Fire Code.

3. Closed piping system containing flammable or combustible liquids or gases utilized for the operation of machinery or equipment.

4. Cleaning establishments that utilize combustible liquid solvents having a flash point of 140°F (60°C) or higher in closed systems employing equipment listed by an approved testing agency, provided that this occupancy is separated from all other areas of the building by 1-hour fire barriers constructed in accordance with Section 707 or 1-hour horizontal assemblies constructed in accordance with Section 71 1, or both.

5. Cleaning establishments that utilize a liquid solvent having a flash point at or above 200°F (93°C).

6. Liquor stores and distributors without bulk storage.

7. Refrigeration systems.

8. The storage or utilization of materials for agricultural purposes on the premises.

9. Stationary batteries utilized for facility emergency power, uninterruptable power supply or telecommunication facilities, provided that the batteries are provided with safety venting caps and ventilation is provided in accordance with the International Mechanical Code.

10. Corrosives shall not include personal or household products in their original packaging used in retail display or commonly used building materials.

11. Buildings and structures occupied for aerosol storage shall be classified as Group S-l, provided that such buildings conform to the requirements of the
International Fire Code.

12. Display and storage of nonflammable solid and nonflammable or noncombustible liquid hazardous materials in quantities not exceeding the maximum allowable quantity per control area in Group M or S occupancies complying with Section 414.2.5.

13. The storage of black powder, smokeless propellant and small arms primers in Groups M and R-3 and special industrial explosive devices in Groups B, F, M and S, provided such storage conforms to the quantity limits and requirements prescribed in the International Fire Code.


Storage Group S occupancy includes, among others, the use of a building or structure, or a portion thereof, for storage that is not classified as a hazardous occupancy.

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