Replies

1. 
   jlyda | Apr 23, 2020 07:50am | #1

   The math is quite easy actually, it’s just a lot more work on the tools. Figure out your pitch, run, rise and diagonal just like any common rafter. You will need extra wide stock to create an arched rafter. This usually requires laminating plywood together by gluing and screwing 2 pieces of plywood together. Unless you have a very small curve, you can trim out of large lumber stock. Layout the wide width rafter on a piece of plywood in a similar fashion as you would any rafter. Then layout an arc on the rafter. There’s a lot of resources available to show you how to make an arc. Cut the rafter and use it as a template for all the others. If installing an arched hip roof it gets a lot more complex. For the sheathing use bender board or skip sheathing. The tighter the arc the smaller the width of skip sheathing.

2. 
   calvin | Apr 23, 2020 07:55am | #2

   Easy answer,
   Go to a box store and root through their pile.

   Or

   Layout and cut plywood arcs on the flat, infill with 2x well fitted end to end then recut the 2x waste beyond your plywood. Make it so you sandwich and glue the infill to the ply. Nail the crap out of it as you would a header or beam.

   Edit: 2 minds run roughly in the same ditch.

3. 
   florida | Apr 23, 2020 10:12am | #3

   I would frame it as if there were no curves and then eyeball the curve you like on a 2 X 6 or 2 X 8, cut the curve and nail the curved piece on top of the standard framing.

4. 
   Plumb13 | Apr 23, 2020 09:39pm | #4

   Unless your lumberyard sells 2x20s, you'll have to frame the roof normally, then apply a curved facade.

   This is an interesting project in terms of design, but it's going to be tedious work and take a lot of creative swearing. Good luck!