I would like to attach an eyebolt to the ridgeline of my metal roof. I can then attach a rope to that when I need to work on the roof. I am a climber and have the knowledge and gear to secure myself. The rope is mainly to allow me to get up the 10/12 central part of the roof (the ridgeline of which I'll mount the eye-bolt), and not slide off the adjacent 5/12 portions of the roof. It will not be subject to dynamic loading (catching falls); the biggest loads it will sustain are when I haul on it to get up the 10/12 roof (it's impossible otherwise, very slippery).
Since the ridge cap is just a fairly flimsy piece of galvalume, the eyebolt must be secured without reliance on it (and RTV silicon caulked to it). My plan is to drill a hole through the ridge cap, the eyebolt will come through that, and then be attached to the rafters with two u-bolts. Since this is the ridge, it's where the rafters meet. So additionally, I will reinforce the rafters with two triangular shaped steel plates (one on each side of the area where the rafters meet); these will be bolted through the rafter with 2-3 bolts, and then the u-bolts will go through them as well.
This picture shows the detail.
Best Answer
If I may suggest an alternative since putting a hole in any roof is better avoided.
I have a 10/12 pitched roof and I use an extension ladder with a stand-off stabilizer to reach the peak.
The ladder is laid flat on the roof with the stabilizer pointing skyward. Extend the section and slide upward towards the peak and then flip the ladder so the stabilizer hooks over the peak.
Climb up the rungs which offer both hand and footholds. Once you’re at the peak, tie off your safety line, hoist a plank to lay on the opposite side of the peak and insert through the top rung. Lash it off or use pipe clamps and you’ve reinforced the setup. I have used it to rebuild chimneys, antenna work, placing hundreds of pounds of brick, etc... on it.