Guard opening limitations

[Codegeek]

I'm dealing with a guard assembly on a roof which would fall under the provisions of 1013.5 in the 2009 IBC. Guards are to be constructed so as to prevent the passage of a sphere 21 inches in diameter. The IBC Commentary has this illustrated as shown. If the purpose of the guard is to keep someone from falling through, would not vertical rails be required as well? What's to keep someone from falling through a 21 inch opening that would extend for several feet? Just asking for curiosity sake more than anything. Thanks.

View attachment 1902

View attachment 1902

/monthly_2013_08/guard.PNG.d7c6f401a485966cc9b0efdde638921f.PNG

 

[fatboy]

I would guess that the assumption is if there is a 21" limitation, whether it is vertical OR horizontal, it is sufficient to prevent passage.

 

[Inspector Gift]

IMHO, a horizontal guard runs "across" the natural path of a fall, and is more effective in blocking the fall.

 

[Codegeek]

Inspector Gift and Fatboy, I appreciate both of your responses. I may have someone arguing with me so I wanted to play devil's advocate to see if it was warranted.

 

[north star]

( + + + )

Codegeek,

By the shape of a sphere, ...the 21 inch dimension will apply to both

the vertical and the horizontal planes......Vertical guard railing will

be required !........Also, ...the vertical guard railing will [ typically ]

be part of the designed load bearing capacity of the overall railing

system [ RE: Section 1607.7, `06 IBC ].

( + + + )

 

[Codegeek]

( + + + )Codegeek,

By the shape of a sphere, ...the 21 inch dimension will apply to both

the vertical and the horizontal planes......Vertical guard railing will

be required !........Also, ...the vertical guard railing will [ typically ]

be part of the designed load bearing capacity of the overall railing

system [ RE: Section 1607.7, `06 IBC ].

( + + + )

That picture comes directly from the 2009 IBC Commentary. I used it as an example since it doesn't show the vertical member.

 

[GBrackins]

good question, do we interpret the 4" sphere for balusters on a residential deck the same way?

 

[tbz]

I'm dealing with a guard assembly on a roof which would fall under the provisions of 1013.5 in the 2009 IBC. Guards are to be constructed so as to prevent the passage of a sphere 21 inches in diameter. The IBC Commentary has this illustrated as shown. If the purpose of the guard is to keep someone from falling through, would not vertical rails be required as well? What's to keep someone from falling through a 21 inch opening that would extend for several feet? Just asking for curiosity sake more than anything. Thanks.

View attachment 1840

First off 1013.5 is not for only roofs it is for Mechanical equipment in areas that are not accessed by the public or by anyone other than service personel for doing service, just like the guards around the raised platforms in an industrial building like on large presses or in closed warehouses.

So the 21" sphere is based on half of the 42" high required guard. Thus this area is not intended to be visited by just anyone, and truly not kids, think of the A/C unit on a flat roof that is only accessed by a ladder. Protection for the service personel. There are balconies that may have equipment and no door access, these to would fall under this provision and this section is not just limited to exterior, but also covers areas with interior mechanical equipment also.

Look at it as a base protection for someone that had no protection for many years.

1013.5 Mechanical equipment. Guards shall be provided where appliances, equipment, fans, roof hatch openings or other components that require service are located within 10 feet (3048 mm) of a roof edge or open side of a walking surface and such edge or open side is located more than 30 inches (762 mm) above the floor, roof or grade below. The guard shall be constructed so as to prevent the passage of a sphere 21 inches (533 mm) in diameter. The guard shall extend not less than 30 inches (762 mm) beyond each end of such appliance, equipment, fan or component.