Replies

1. 
   BillBrennen | Jun 08, 2005 12:40am | #1

   Maydell,

   Yurts have radial roofs, and they typically have a rope or cable running around the tops of the exterior walls to contain the rafters' outward forces. If you frame a conical roof sheathed in multiple layers of thin plywood, then the ply will restrain the rafters, but an inspector will likely want to see a dedicated system...what if some future owner puts in a long skinny skylight? This would gut the plywood's integrity.

   bill

2. 
   Piffin | Jun 09, 2005 05:45am | #2

   As a matter of correction - Collar ties do not prevent wall thrust/leanout in any system. Rafter ties do. Collar ties are in the upper third of you rroof frame system and are to prevent upward hinge action from high winds.

   In a radial roof, both are done with hardware. A restraining cabel encircles the top plate or wall just like it does as mentioned with yurts or with barrels, or silos

   at top, a metal plate or connector is fabricated for that peak junction

    

    

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1. 
   Sawdaddy | Jun 11, 2005 04:58pm | #4

   Hi Guys,

    

   Thanks for the replies.

   I sure didn't think of a cable retainer around the perimeter. I was thinking something like a tension ring on top of the wall plates or something. That cable retainer is a good idea if I ever do one of these.

    

    Piffin, when I said collar ties , I was just using sort of a generic term. I should have said, maybe ceiling joists or something. Whatever keeps the rafters from pushing out the walls on a more standard roof frame.  But, you figured out the gist of the question I think.

    

   Some time ago, I saw a pic of a small round building with a cathedral ceiling inside right to the peak. (Or maybe it had a hub, I don't remember exactly.) Anyway, I was thinking about that and just wondered, How'd dey do dat?

   Cable retainer...Ahhhh!

    

   Maydell

3. 
   DanH | Jun 09, 2005 07:31pm | #3

   You need a circular retaining cable or "hurricane" hardware at the framing joints to hold the top of the outer wall together. For concrete you'd use extra rebar up there. Otherwise, you need radial joists to hold things together.