Roof job - FA Rope questions

I think I solved it!

Use 2 prusik loops, but with a regular prusik hitch on the upper loop, and a Petzl Tibloc on the lower loop. If I mistakenly grab the upper prusik hitch and it slips, I believe it will stop when it hits the Petzl Tibloc below (unlike a second, unloaded prusik hitch, which I believe would just slide along the rope ahead of the upper, grabbed prusik). And for ascending, IIRC, the Tibloc will just slide up the rope (one way only due to the teeth direction) without needing to be grasped, like the prusik hitch. (Need to check that b/c it's been a while since I've used the Tibloc.) That way, I'll have the best of both worlds -- on ascent, it'll be like using one prusik, plus I'll have the failsafe of the Tibloc to guard against panic grabbing the upper prusik in a fall...

Here's what the Tibloc looks like for those who haven't seen it:

petzl-tibloc-ascender-1.jpg


Does this sound reasonable? (I understand that I'll still need a fig-8 or munter or whatever to descend if I need to...)

JeffGu, what do you think? You've done this kind of roof work...
 
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The sliding Prusik might hit the Tibloc in such a way that it wouldn’t bite into the rope. Another type of device would be more reliable.
 
Woodwork said:
Thanks for all the replies, guys, I've been following along even if I don't respond to every reply.

If I did a "panic grab" on the prusik hitch in a fall, I wonder whether the friction of the rope sliding through my hand would burn me fast enough to make me release it in time not to hit the ground...
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I had a first time groundy drop the rope once on a fairly large piece lowered over edge if driveway adjacent to water meter whilst I was in the bucket.

After the cut all I could do was grab the tail with my hand and slow it as much as I could whilst the synthetic glove melted to my hand.

Different circumstance but when a priority becomes established pain isn’t such a big determining factor...
 
Well, now you guys have me bummed because I came THIS CLOSE to buying a Unicender when Sherrill had their big sale a month or two back...but money is real tight, so I didn't.

There's got to be a safe way to do this with webbing and/or rope loops or something fairly simple that I can tie or rig. How did they do it in the olden days before gadgets?

I've got the tiblocs, and a bunch of biners and a couple fig-8s and webbing and some micropulleys and a rack (heavy) but no gadgets to speak of...was hoping to do this without them.

Thanks again for all the advice.

Jeff
 
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There are hitches that can only be used to ascend the rope, it is extremely difficult to make them descend. Maybe one of those for the top hitch and use the bottom Prusik, or Klemheist for positioning and descending. Gary Storrick’s website has about a dozen that are ascent only.
 
Woodwork said:
Thanks Brocky and Tom, I'll look at Gary Storrick's website.
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When I was learning about rope ascent I spent many hours there. In the end I read his whole page and looked at all of the various tools. His 'letter' 'figure 8's are a hoot.

Looked the various bobbins. I think thats the tool for you since you'll be on your feet you can move up the rope pretty well.

I used a Hewbolt for a while. I good belay/rap tool. I sitll like it but don't have any application for it
 
Mowerr said:
Do u have really bad balance?
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Not bad balance, but it's a 12-pitch roof. Looks steep from below, but up there it feels vertical. You can't ascend without a rope. I'll have roof jacks, but still, one misstep and it's 20-30 ft to the ground at 10m/sec². (That's if you're lucky and don't bounce off the scaffolding on the way down.) And there will be lots of stuff to slip/trip on, like loose shingles, loose tarpaper, loose nails, sawdust, dew, air hoses, tools, etc etc., and I don't do this for a living so I'm not accustomed to it. (I'm also not a tree guy, unlike most of the folks here, I suspect.) Plus I'm in my mid-50s.

Maybe I'm just paranoid, but I know of multiple people who have either been killed or wheelchaired falling from roofs...
 
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Woodwork said:
Not bad balance, but it's a 12-pitch roof. Looks steep from below, but up there it feels vertical. You can't ascend without a rope. I'll have roof jacks, but still, one misstep and it's 20-30 ft to the ground at 10m/sec². (That's if you're lucky and don't bounce off the scaffolding on the way down.) And there will be lots of stuff to slip/trip on, like loose shingles, loose tarpaper, loose nails, sawdust, dew, air hoses, tools, etc etc., and I don't do this for a living so I'm not accustomed to it. (I'm also not a tree guy, unlike most of the folks here, I suspect.) Plus I'm in my mid-50s.

Maybe I'm just paranoid, but I know of multiple people who have either been killed or wheelchaired falling from roofs...
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Doubt they were reaching for a hitch on their way down. And I doubt you will too. I bet your going to reach out towards where ever you heading. Maybe if u did do trees for a living and had that burned into your instincts. I bet you'd dig your fingernails into the plywood or shingles but id be surprised if you grabbed a prussik and rode it all the way down. I think the best way is to use stopper knots below you when doing something sketchy. But better safe than sorry...good luck
 
Mowerr said:
Doubt they were reaching for a hitch on their way down. And I doubt you will too. I bet your going to reach out towards where ever you heading. Maybe if u did do trees for a living and had that burned into your instincts. I bet you'd dig your fingernails into the plywood or shingles but id be surprised if you grabbed a prussik and rode it all the way down. I think the best way is to use stopper knots below you when doing something sketchy. But better safe than sorry...good luck
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When doing rescue or storm work with prusiks on static line it is mandatory to tie a stopper where the fall risk point is on the rope where you are working so you are ‘safe’ hands free.

The other concern is pendulum, whereby you don’t actually bounce to get injured but swing into another part of the structure. So corners of roof present the largest danger of this...
 
Thanks, Mowerr and Chaplain242. I guess you can tell I don't know what I'm doing by my not thinking of a stopper knot...Duh! (That largely solves the issue, it seems to me, assuming I tend my slack on the prusik.)

And you're probably right -- if I fell, I wouldn't be grabbing for the hitch -- I'd be grabbing for something to hold onto. My carpenter brother said he stopped a slide once with the claw of his framing hammer...though not on 12 pitch!

Sorry if I'm overthinking this guys. Just new to it and want not to make any rookie mistakes, and appreciate your patience in explaining it to a newbie.

I'm sure I'll have more questions as I go along, but will try not to belabor it. Thanks.
 
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Wait till it rains, I tried to finish a new roof with silicone before rain came down and ended up flying down a 50’ roofing sheet. Only thing saved me was I was travelling so fast I skipped across the ground instead of landing vertically...
 
Brocky said:
The dynamic rope would be better if slack is anticipated.
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Brocky - I had kind of decided to use my stretchy rope (Bluewater Accelerator 10.5mm
Specs: Impact Force: 8.0 kN • UIAA Falls Held: 11 • Static Elongation: 7.2% • Dynamic Elongation: 31.8%) on your comment above, but I'm also thinking that since I'll be using the rope for WP as well as fall safety, my non-stretchy tree rope (Yale XTC Fire 12mm) might be better, so I can avoid fighting the springy-ness of the dynamic rope when work positioning.

I guess the question is, how much slack am I safe falling on, on the non-stretchy rope, if I use that? Would I need to tend it religiously, or could I safely work on 3-4' of slack in the prusik loop? (The specs of the Yale XTC Fire are: 12mm (1/2”) • 16-strand • 6,200 ABS • 1.4% elongation at 10% ABS • 7.5 lb per 100')

For example, when standing on the roof jacks, I wouldn't need the rope for WP, so I could have slack there. But if I climbed up above the roof jacks, I would need the rope to hold me in place there while I worked, if that makes sense.

I found and saved a web page that showed "Fall Factors" and talked about what was survivable or whatever, but I don't really understand that. Is it the number of Gs you pull that harms a person, or is it an issue of your guts tearing loose from their moorings? It seems like they're talking about how suddenly you stop, and thus how many G forces you experience, as a result of various falls.
 
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Unless you’re at the edge, a slip would cause you to fall on the roof and then start sliding, causing friction to slow you down some.
 
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