pre-building a shop roof

[blacktruck]

i'm building a 40wx60Lx16H shop on the farm, ive heard some people talk about framing the roof, then getting a crane to place it on top of the walls in one piece. Anyone ever do this? Is it even safe? To me it seems like a lot of stress on the roof to be picked up like that, but it also would be alot easier to build it on ground level instead of 16ft in the air. BTW the materials package for the shop includes engineered trusses.

[bkrahmer]

If you were building a roof that had a ridge beam, or even a substantial enough ridge board, AND you had a completely flat area big enough to frame the roof like you are suggesting, you could do what you are talking about with the appropriate load-spreader and a crane. It seems like a lot of trouble to me, though. You'd save some time aligning the trusses to their spacing, but that's about it. It's easy enough to frame up platforms and have your sheathing hoisted up to your roof, felt is easy enough to handle. If you're using metal roofing, and had to drag them up a ladder, they'd be a lot easier to handle if you do the metal in two courses.

[Roy J.]

I've got to see this crane.

[Rich]

I saw it done last summer. They built a 30x60 roof in 2 sections and craned into place. I didn't get to see them crane it but did see them framing it on the ground off from some temp beams. I don't know if I would attempt it. I think in about the same amount of crane time to pick and place several sections of roof I could set the trusses and have them fully braced.