i know the basics if you question yourself dont do it… i was doing a mock inspection on my mothers home, as i walked on the roof, which i had done as a child, it felt very soft, my mother said she saw parts of the roof bend in where i was walking, but it felt safe… basiclly when is a roof not worth going on? How much is too much weight of a person on a 20 year old roof? it was only weathered, with a small leak (or stained leak) near a skylight, but nowhere near where i was when it felt as soft as it did…
Adam, if the dwelling is old and questionable, personally I would do the attic inspection first and look for signs of age, leaks, rot from poor ventilation, bathroom exhaust, dryervents, and anything that could possibly contribute moisture, and also look at the framing, spacing, truss chords missing etc.
Then I would inspect the roof exterior.
I think that would help in determining soft spots.
Hope this helps a little.
Marcel 
Adam, no offense meant, but what is the size differnece between yourself now, and yourself 20 years ago? (retorical question :mrgreen:)
A 250 pound man will cause the sheeting to bend a lot more than a 90 pound boy.
lol, i knew someone was gonna be a smart ***… lol… i actually am about 265 and see i know about checking the attic first too, but the probelm was this roof was above the livingroom addition with no space to get near it without cutting… im just asking so i know for future inspections when the roof should not be attempted, anyone have any pics of roofs that look safe but werent? what gauge do ya’ll go by?
I’m in the …ahem… 265 range and I walk roofs every day. They bend. As said, if I’m unsure I do the attic first.
Most roofs these days are sheathed with 7/16" ply with trusses 24" oc. Step in the middle and it’ll bend. If it’s bad, step in the middle and you’ll hear a sound you won’t soon forget! 
lol, thanks… but on the same topic how good can the report or inspection be if say, its a 3 level roof, and all 3 are unsafe so theres no way your getting to the 3rd? how good can one of the most inportant things to inspect doesnt get inspected besides by a camera with zoom or binoculars… how often does this happen?
(sorry to go off topic)
There are a whole plethora of things to consider when walking a roof, not just if it is safe. Yes, that is one of the major considerations before you even step foot on it. Another is will you cause damage that was not there before you got on it. Shingles can easily “smudge” if you walk on them on a hot day, clay tiles, concrete tiles, etc. can be easily broken if you do not know how to walk those. The type of shoe or boot makes a huge difference both for your own personal safety as well as causing damage. Metal roofs can become slicker than snot on a doorknob.
I tend to stay close to areas of the roof I know are structurally going to be more sound and firm. On a steep roof I will almost always use the valley to go up to where I need to go. I do not nor need to get too close to the edges. If I slip down, I do not have time to react and try to avoid that sudden exhilaration of free falling followed by the hard and painful landing. I do not stay on the roof any longer than absolutely necessary. I do not fetch things on the roof thrown up on the roof by the kids, it ain’t my problem and I would hate to get injured retrieving some kids Frisbee or hula hoop (yeah, they still make them).
People will often tell you it is a “new” roof. If you can, get them to show you the sales receipt. New to them often turns out to be anywhere from a couple of months to several years. New roof most often means new shingles. I could retire now if I had a dollar for every new shingle job I have seen over old broken, rotted wood. Many roofers will only replace a couple of sheets of sheathing if it is written into the contract and will skip out on that if they can. Ive seen sheet metal covering large holes; sometimes with nails driven thru the metal and sometimes roofing bull (tar) being the only thing holding that patch of shingles on. Its already been said, go into the attic first to see what is going to be holding you up. I know there is a lot more but I don’t want to hog the thread.
To answer that; I can tell a whole lot more from inside that attic than I can on the roof especially with shingles.
Alright Adam, you did not tell me all that stuff.
Now that I know you are a big boy like that, don’t wallk the roofs, the warranty does not cover it. Ha. Ha. LOL
Geeze, I stuck with a bunch of big guys, I better get out.
I must be lucky, I am still middle weight class, well at least for now.
Marcel
big and tall my friend, big and tall… thanks alot for all the info guys… also what do you mean just dont go on the roofs? but then how good can a report be?
Adam, I have been wrong before, and maybe a man of your size, can fly like a butterfly and sting like a bee.
Well, he was a heavy weight wasn’t he. ha. ha. But I don’t think he walked roofs.
Marcel 
and doug feel free to hog my threads as much as you want, you are one of few who actually go out of there way to help me understand your world a bit more, it is much needed and appriciated, and i thank you sir…
You are welcome. Glad I could help.
I would have thought OC would be closer to 18" or 16" in an area subject to hurricanes and tornadoes. Here in San Diego, we seem to prefer 18", perhaps because of both earthquakes and high Santa Ana winds.
Well I’m sure glad to hear someone else other than me say that.
That statement might be true but part of the job entails bells and whistles and not only does it look good but I suggest you get on where you can, since moisture intrution is most likely what gets us sued when we miss it.
If you can see cracked or badly installed flashing from the ground count your blessings.
Ladders, binoculars, zoom cameras, first-floor looksee from second-floor windows, and a good looksee from surrounding properties also help.
However, what I’ve found most effective in my area, due to its 11 months of hot, dry sunshine and Santa Ana winds, is to teach my Clients how to easily and inexpensively take care of their roofs. Roofing contractors here appreciate my efforts and my referrals to them, which puts them into my “Power Partners” network.
After 4/12 I agree Russ ,but remember I have ice on those suckers
Ice? That belongs in a margarita glass. :margarit:
Get a big glass, hehe
Inspect your ladder(s)/equipment and the attic stairs before you use them to inspect any attic/roof!
Around here some fairly large (bigger than both of my feet) pieces of 20-25 gauge sheet metal are used for “professional” patches. I make a mental note of where these or other patches are, from the attic, before treading any roof. Usually try to stay at least 18-24" away from any penetrations/flashings even after attic review, just my method.
Height has never been an issue for me but I have gotten up only to realize I may not be as able or comfortable coming down. It goes with the territory. You’ll lean what your body/nerves are capable of very quickly.
Everyone be safe out there. Your livelihood or life are at risk.