How big is it?

We just did some sections on a 10,000 sq ft house pre built on the ground. We had different sections being built at the same time. I don't think building a replica of the house is going to save you any money. Frankly it'd be a waste of time. Just get some masonry blocks and run some 2x4 across them. Square it up. Level it as best as you can and then go to town. Make sure the math works everywhere. We were talking about what the fastest way to do this was. One section we took the time and leveled the platform squared it up. Pulled layout on it and built the roof. The other section we didn't square or level anything. Just pulled all the dimensions. Ran sub fascia. Squared the hip jacks eave jacks etc and they both came out perfect. As long as you're constantly checking your dimensions and using geometry you should be fine.

We've done them both inside on the slab and out in the dirt. I'd pre build a few sections rather than try to build the whole roof. As long as you're confident with all of you dimensions, add all of the bracing etc. it's much faster on the ground.

It's pretty small 22x42 I ended up figuring it out (at least I'll find out on crane day) I maybe spent more time leveling than I needed to but it worked out. thanks mike, do you ever sheet part of your roof on the ground? I had a friend suggest it. Seems pretty sketchy to me.(guess I don't trust myself enough.)Also how would you do your insulation stops in your attic space?

We sheathed the overhang in the one pictured above just to get everything squared up. We've also left off the first run on another project and sheathed above it so that we could still get all of the embedded tie down on and twisted over the tops of the trusses.

Last house we just did had sections of trusses. 44' long. Built them in the middle of the road. Braced them well enough to lift in a pack of 7 trusses. Other section was a 28' length by 18' wide we did in another lift. These were both groups of the same trusses though no over framing involved.
For cottage roofs, we generally build them on the first floor deck and lift them off. Could sheet them this way if you really wanted. Generally we don't sheet before hand. Some day I will do it.

Our post frame buildings are mostly simple rectangles. We build four trusses at a time four foot on center for a sixteen foot by 30 foot roof section for example.

We finish all the framing on the ground except for the diagonals so we can square things up once the roof section is set on top of the wall.

We have found it is much faster to make minor adjustments once the roof section is set than building the sections on uneven ground and then locking it all in with the diagonal bracing.

We set the roof section up on the wall, true things up and then install the bracing to lock it square.

We have tried it both ways and prefer to leave the diagonals off and adjust if needed then lock it down with diagonals.

When I did framing I worked with some guys that would sheet the whole roof. They would build the 1st deck, then 2nd, followed by the roof; all on top of one another. They would build it in the parking lot. Crane set up the 1st deck. everyone would throw up the prefab walls. then followed by 2nd deck. so on....
They did this mostly on town homes or apps. I didn't like it personaly.
You ran your but off on crane day getting everything up. If you ran into problems it was a mess. plus a lot of patch work.

We have also put all the cornish on the walls before standing them.
Just build a ladder to match overhang. Get the distance down, layout ladder blocks to match truss (so they can be nailed to truss tails).Just be careful when setting the truss, if they sit down on the blocks it can tear off the cornish.
This worked good. Only thing to do off ladders is the returns.

We've Done porches like this as well. put them on the wall, before standing them. It makes the wall heavy as....

The only few times I've ever pre-built something of this nature was dormers. However, I could see it helping in some cases, but not by no long shot.

I remember a time we were thinking about pre-building a section of the roof on the ground, because it was a couple stories higher than any floor level below.(Kinda like a 14'x14' wide cupola) We finally decided to just ladder climb the material up to the installer.

Sorry, I don't see the benefit in this situation. To me, it's just so accessible from the ground to hand up and frame. But, I'm not saying it's a bad idea.
By the way, how much time would you compare in the difference?

knucklehead said:

http://s252.photobucket.com/user/tompirch/media/IMAG0784.jpg.html

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http://s252.photobucket.com/user/tompirch/media/IMAG0784.jpg.html

First off you can avoid every single trip up the ladder. Also having to move the ladder and or walk the wall / beam. I'd venture to say on the last one we did it cut our labor time by as much as half. But. To each their own. The majority of roofs we build are 30+ feet bearing elevations so safety is also a large concern.

ObuckiO said:

Sorry, I don't see the benefit in this situation. To me, it's just so accessible from the ground to hand up and frame. But, I'm not saying it's a bad idea. By the way, how much time would you compare in the difference?

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although they are close to the ground, framing porch roofs on the ground is super convenient, because you can do all the beam work too. And they are really easy to set, at least in the situations i've experienced

The roof you have in the pics are complicated enough that I can agree with your method. I've just never really took the time to get in the habit of doing them down on the ground. It's also hard to say if we've ever had many good spots to do them on the ground, either.

I would like to test an easy one someday.

mikecocozza said:

First off you can avoid every single trip up the ladder. Also having to move the ladder and or walk the wall / beam. I'd venture to say on the last one we did it cut our labor time by as much as half. But. To each their own. The majority of roofs we build are 30+ feet bearing elevations so safety is also a large concern.

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I think it a lot easier. We've also done sun decks like that.
We did some SD's that were double stacks. IMO it was a ton easier.
I don't know why I didn' take pictures back then. I guess it was because no one had a cell phone with a cam. Heck, no one had a cell phone.

mikecocozza said:

First off you can avoid every single trip up the ladder. Also having to move the ladder and or walk the wall / beam. I'd venture to say on the last one we did it cut our labor time by as much as half. But. To each their own. The majority of roofs we build are 30+ feet bearing elevations so safety is also a large concern.

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Got one more section hiding on the side of the house. A group of 6 38' span trusses.