sloped rafter onto circular wallturre

huangyhg

sloped rafter onto circular wall/turret
i have this sloping rafters that intersect a circular wall (turret).  i cant think of a way to frame this easily.  if i create a builtup ledger made out of thin plywood to but around the wall, then it has to be 3 dimensional curve (parabolic equation probably?).  i think that will be too much to ask the framer to do.  do you guys have any idea how to support the rafters intersecting this curved wall?
never, but never question engineer's judgement
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you need to make the top plate supporting the rafters into a tension ring by adding continuos metal strapping around the plate of sufficient strength to take the tension ring load.  bear the rafters flat on the plate, notching them forflat bearing, and add metal side clips to take the horizontal kick into the tension ring.  depending on the number of rafters you have and the size of the turret (diameter) simpson may have a connecting clip for the rafters at the peak.  may have to cut some rafters short and head them off into the adjoining rafters.  
basically real simple construction for the roof.  cutting the curved wall plates, top and bottom, should not be a challenge for a good framer.
mike mccann
mccann engineering
i think u missed my question.  i am not talking about the turret roof.  i have lower sloped roof intersecting a circular wall.  thinking about how to support the lower roof onto that wall.
never, but never question engineer's judgement
ok.  i'll try again here.  hope i understand this time.  
how about monotrusses that nail off to and intersect top and bottom to each wall stud (extend top and bottom chords 3.5 to 5.5")?  wrap metal strap around stud if needed.  block below if needed for bearing.  could space studs closer together to keep plywood to 24" max span at the outboard end of the trusses.  or could use thicker plywood and go to 48" at the outboard.  size the wall studs for the tension/comp load from the trusses.  roof plane would not be curved, but consist of many planes.  the more trusses, the more planes and the closer to looking curved.
mike mccann
mccann engineering
heh.. i think you completely missed my question.  it is 2x rafters from a gable roof that is sloping 5:12.  in the middle of this 5:12 plane you have a circular wall cutting trough the plane.  how do you hang/bear the 5:12 joists onto this circular/curved wall?
never, but never question engineer's judgement
can they bear on straight blocking between the turret studs, or some similar variation of this?
ucfse.. i think thats what i am going to do.  at first i thought they were going to build the turret first and put exterior sheating, then maybe they should not put the plywood until they build the lower roof with blocking then put plywood.  thx.
never, but never question engineer's judgement
in that it appears you have already solved your problem, and i have already blown it twice, i think i'll stop when i'm behind.  maybe next time?  cheers...
mike mccann
mccann engineering