Despite what someone claimed above about a deck screw holding their weight, the static weight of you suspended from a rope is not the same as the acceleration, and momentum force of arresting your fall. Yeah, you'll get a sudden jerk and pause as you fall, then when the anchor on the roof fails, you'll keep falling to the ground.
It's a lot more force than you'd think and some screws thru the roof to the joists/decking on your roof are not designed to withstand that kind of sudden force. EDIT to add: Learned this in my OSHA 10hr Class ~20-years ago.
If you're that uncertain getting on your roof, hire someone. I guess you need to decide what your life and/or health is worth to you and your family.
I pay someone $120 two times a year to clean my gutters b/c I hate ladders and have zero desire to lug a 30-foot ladder around my house scared out of my mind about falling to the ground.
My wife's senior year in Aero at A&M, one of her professors fell off a ladder while working on his house and was paralyzed from the waste down. He did come back and continue to teach at A&M and I believe past away a few years ago.
A friends 80+ yr old father was forever a DIY guy fell off his gazebo, a mere 8-feet off the ground, last year and severed his spinal cord at the neck. After 2-days in the ICU, he communicated thru blinking to let him go. He was in otherwise good health.
