I don’t know what all the detail on your roof plan is supposed to be, so let me show you a simplified version. I take this to be a variation on the general problem of constructing a curving ramp. I’ll show you the manual method I have always used, although I expect you’ll also see how this can be done with several plugins.
I start by making sure that the curves are constructed with segments that are as close to uniform in length and number as possible. Then I connect corresponding pairs of endpoints with radial lines, raising these into a series of hoops, or “hurdles” as I call them, each consisting of two verticals and a cross member. In the back is a profile of the slope of the ramp, which determines the height of each hurdle crossbar. I raise each crossbar to the correct height, snapping to the height on the profile.
Finally, its just a matter of stiching over the framework to create the triangular surface faces, then softening/smoothing the mesh. A plugin like Curviloft could do that for you.
-Gully