I'd make a wager that every single one of the roof raise projects you see on the skoolie site and elsewhere use techniques similar to that of the original manufacture. That is to say, sheet metal skin with clamping force fasteners at regular intervals.
The structural component, the ribs, are extended in a method generally accepted for building up structural components when made from steel, which is to say welding layers of structural reinforcement to a core.
If you prefer to retain a one-piece-virgin-part approach, then you'll be replacing each of those ribs with a new one, which would necessitate rebuilding the entire coach from scratch.
I am curious to know how you plan on constructing a better mousetrap here. The two generally accepted methods of constructing vehicles that I can think of are either:
1) unibody design - full presentation shaped components fused together with adhesive, spotwelds, or a combination thereof to form a resilient engineered unit
2) sheet on frame - structural subframe designed to carry compressive loads, with sheet fastened or adhered to resist shear and tension loads.
These two approaches comprise about every vehicle I can think of driving by when I look out the window.
Other methods, like a monocoque seem neat and exotic, but expensive to construct.
Originally Posted by jake_blue
I simply don't know how resilient that fastening method would prove in an accident, IE a decade of road vibration and flexation followed by a rollover in which the loads and stresses suddenly shift to the roof or more accurately laterally against the roof. I think we've all seen the pictures of school buses rolled over and how you'd be hard pressed to tell they even rolled after they've been righted. The same is not true of RVs and motorcoaches. I think in such an event the shock/stress would trigger failure if not in the weld itself than in the surrounding structure and would travel along the weld creating greater failure than a riveted seam. Bolted/riveted fastening can distort and the most stressed points can fail but as the fastening 'gives' it releases the kinetic force of the impact and then at some point the rivets distort but don't fail entirely until the force is completely dissipated. You can end up with a bent bus but not a collapsed bus. At least that's how I'm looking at it. I don't want to see a raised-roof skoolie turned into a convertible in a rollover and I definitely don't want to be in one.
FWIW though, the engineered solution I'm working on would lend itself pretty easily to welding or bolting/riveting. So perhaps there is a value to each method and the end result could be a stronger and more resilient product. If this is something a pro-welder would like to explore with me, I am serious about the idea of raising a roof just to roll it over and prove my solution is comparable in rigidity to the OE design.