Suggestions for odd curved roof

[Christina_Girerd 59]

I'm have a hard time trying to create the roof shown in the attached photos - one plan, one mostly elevation.  This roof is on an octagonal structure.  So far, I am not having much success, despite spending a lot of time playing around with the angles at eave and ridge for the curved roof plane.  I know I need multiple roof planes, and have used a flat piece of roof for the first 25' or so of the roof with about a 1:12 pitch.  Then I start a second roof plane that is curved.  It seems that if I can get a steep enough slope up toward the ridge to match the actual roof line, then the lower part of the roof has a negative curve and goes below the first roof plane, which is no good.  I'm wondering if I need to have more than 2 roof planes per segment to get this particular roof shape...  

 

The third image is the best attempt so far, and that is with one flat roof plane and one curved plane.  But I'm hoping to get closer to the actual roof.  Any suggestions?  This is my first time working with curved roof planes

[glennw 761]

Christina,

 

Can you post some details of the geometry like pitches, heights, radii, sizes, etc?

[rlackore 355]

Here is my attempt. The proportions are probably all wrong. Basically, I used three roof planes for each octagon side to achieve a reasonably smooth transition. The trick is to draw each plane along the ridge of the lower one, set the overall pitch to achieve the new ridge height you're after, then curve the plane.

 

 

steeple.plan

[Christina_Girerd 59]

Thanks Robert - that was very helpful!  I realized one of my problems was that on the innermost steeply curved roof plane, I was only adjusting the angles for the curve at roof and eave, and as I was trying to figure out why I couldn't get mine to do what yours did, I saw your curved plane also adjusted the roof pitch.  Duh!  Somehow I had thought that part was no longer applicable when I was dealing with the curved angles.  Anyway - now I know!

 

Glen - I don't know any of those details - I am only doing this based on photos, the ever helpful google earth shots and a landscaping site plan.  Just trying to get it to look right for large scale 3D views and that pitch adjustment was the missing piece.  Thanks for asking though. 

[MarkMc 431]

Here's one with two roofs-I think getting the eave angle to match the lower pitch creates a smooth(er) transition- just realized that after fiddling for a while- these angles are close but not exact. I just like trying the odd ones.

 

swooproof.plan