Roof access

[Sifu]

2018 IBC/IMC Less than 3 story, no stairway to the roof. Access provided by a permanent ladder to the roof on the 3rd floor. Is there a minium size required for the access opening? I can't find one anywhere. I thought there were discussions about this, but in the 2018 I can't find anything. If it isn't prescribed, what good would a permanent ladder be if the opening isn't large enough to climb through?

 

[steveray]

Not great but...IMC 306.5

7.
Climbing clearance. The distance from the centerline of the rungs to the nearest permanent object on the climbing side of the ladder shall be not less than 30 inches (762 mm) measured perpendicular to the rungs. This distance shall be maintained from the point of ladder access to the bottom of the roof hatch. A minimum clear width of 15 inches (381 mm) shall be provided on both sides of the ladder measured from the midpoint of and parallel with the rungs except where cages or wells are installed.

 

[Sifu]

Thats all I could find as well. So wherever the ladder is the opening at the top must allow 30" behind the climber and 30" from the center line.

 

[Yikes]

I think this was discussed recently on another thread. Although it is not building or mechanical code, OSHA 1910.23(d)(2) and 1910.23(d)(13)(ii) effectively requires 30" wide x 37" deep, which is not a manufacturer's standard size. By the time you get through adding deflectors, blocking out the trusses for the opening, and considering how often roofs need to be accessed for additional equipment, solar PV cleaning, etc., best practice is just to buy a standard 48"x48" hatch.

 

[Sifu]

I think this was discussed recently on another thread. Although it is not building or mechanical code, OSHA 1910.23(d)(2) and 1910.23(d)(13)(ii) effectively requires 30" wide x 37" deep, which is not a manufacturer's standard size. By the time you get through adding deflectors, blocking out the trusses for the opening, and considering how often roofs need to be accessed for additional equipment, solar PV cleaning, etc., best practice is just to buy a standard 48"x48" hatch.

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YES, I knew I had seen this. Thanks. The original plan was 2 4'x4' hatches. Framing restrictions have created a problem and they asked if they could reduce it, which I say yes but wanted to find them a minimum to stay within. I just told them to follow IMC 306.5 for ladders.