Single Story Roof Access

[glzath]

A client wants to replace an exterior roof access ladder with an exterior access stair. The roof height is ~16' with no parapet and is unoccupied. Access will be for maintenance, only.

Checking IBC 2009 I can not find anything definitive regarding the stair design needing to meet chapter 10 riser/tread requirements. There is info regarding alternating tread devices, ships ladders, roof hatches, 4-story building roof access penthouses, etc. There is the "outdoor conditions" requirement regarding water collecting, but this would not be an issue as the stairs would be constructed out of open grating.

Due to space considerations, we would like to design an OSHA complaint stair where the treads/risers would not conform to the IBC, but would meet OSHA requirements. Note that we will have guards extending out 10' from either side of where the stairs meet the roof.

 

[mtlogcabin]

I believe an OSHA compliant stair would be acceptable

Chapter 10 deals with "Means of Egress"

1003.1 Applicability.

The general requirements specified in Sections 1003 through 1013 shall apply to all three elements of the means of egress system, in addition to those specific requirements for the exit access , the exit and the exit discharge detailed elsewhere in this chapter.

MEANS OF EGRESS. A continuous and unobstructed path of vertical and horizontal egress travel from any occupied portion of a building or structure to a public way . A means of egress consists of three separate and distinct parts: the exit access , the exit and the exit discharge .

The roof is not an occupied portion of the building nor is it part of the means of egress as defined in the 3 distinct parts

Therefore Chapter 10 is not applicable in this scenario.

The code recognizes that the placement of equipment and access to it is limited to service personnel and traditionally is not located within a "Means of Egress". Section 505.5 comes to mind along with attic access and roofs allowed to be accessed by ladders.

Talk with the AHJ.

Section 104.10 is also an option since space constraints are effecting the design

A real stretch would be to call it a Fire Escape under 3406

3406.1.3 New fire escapes.

New fire escapes for existing buildings shall be permitted only where exterior stairs cannot be utilized due to lot lines limiting stair size or due to the sidewalks, alleys or roads at grade level. New fire escapes shall not incorporate ladders or access by windows.

3406.4 Dimensions.

Stairs shall be at least 22 inches (559 mm) wide with risers not more than, and treads not less than, 8 inches (203 mm) and landings at the foot of stairs not less than 40 inches (1016 mm) wide by 36 inches (914 mm) long, located not more than 8 inches (203 mm) below the door.

 

[Gregg Harris]

209 IBC

1209.3 Mechanical appliances. Access to mechanical appliances installed in under-floor areas, in attic spaces and on roofs or elevated structures shall be in accordance with the International Mechanical Code.

While not directly pointing to a code article. equipment access on roofs is specified under IMC Section 306 and while ladders are specifically addressed to access a roof indirectly are stairs in the highlighted section. I have this noted as a code proposal change to ad to 306

SECTION 306 (IFGC)

ACCESS AND SERVICE SPACE

[M] 306.1 Access for maintenance and replacement. Appliances shall be accessible for inspection, service, repair and replacement without disabling the function of a fire-resistance-rated assembly or removing permanent construction, other appliances, or any other piping or ducts not connected to the appliance being inspected, serviced, repaired or replaced. A level working space at least 30 inches deep and 30 inches wide (762 mm by 762 mm) shall be provided in front of the control side to service an appliance.

[M] 306.5.1 Sloped roofs. Where appliances, equipment, fans or other components that require service are installed on a roof having a slope of 3 units vertical in 12 units horizontal (25-percent slope) or greater and having an edge more than 30 inches (762 mm) above grade at such edge, a level platform shall be provided on each side of the appliance or equipment to which access is required for service, repair or maintenance. The platform shall be not less than 30 inches (762 mm) in any dimension and shall be provided with guards. The guards shall extend not less than 42 inches (1067 mm) above the platform, shall be constructed so as to prevent the passage of a 21-inch-diameter (533 mm) sphere and shall comply with the loading requirements for guards specified in the International Building Code. Access shall not require walking on roofs having a slope greater than 4 units vertical in 12 units horizontal (33-percent slope). Where access involves obstructions greater than 30 inches (762 mm) in height, such obstructions shall be provided with ladders installed in accordance with Section 306.5 or stairs installed in accordance with the requirements specified in the International Building Code in the path of travel to and from appliances, fans or equipment requiring service.