My old man was replacing his timber garage last year and employed the services of two local alcoholics to do the job.
(He has this amazing habit of trying to save a couple of quid and ending getting completely shafted)
I suggested that, to save tearing the roof up, they should prop it up and then remove and replace one side at a time, since the new sides were sitting in the drive.
Simple, I would have thought!
I returned later to find this incredibly heavy roof held up by one side of the shed and 'floating' a foot lower than it should be on a collection of 2x2's propped at crazy angles all the way around the other three and then turned to me and said that they couldn't get the other sides on now!

No Shit Sherlock!!!

There was nothing else for it, I told them to knock the props outs and get to fuck, then spent the next 4 days building the thing and roofing it myself.

(a couple of months later the old bastard demanded that I get the bike out of there (just as winter was hitting) so he could park his car in it, so I arranged storage for the bike and a week later his car was being left on the drive again since it was such a tight fit he'd dented the car 3 times getting it in and out of it..something I had pointed out to him previously.)