Bay window hip roof, wall cleat backing angle
Posted: Sat Jun 04, 2016 8:56 am
Hi everyone,
I am currently building a small hip roof for a bay window. It is a standard 45 degree window with about a 20" projection. I have build one hip roof like this before without trouble, so I decided to give this one a bit of a flare. I played around with different slopes and curves, and ended up settling on a 12/12 pitch, with the radius of curvature on the common rafters set at phi times the rise. I had a hard time finding info on the traditional curves on these roofs, so just went with what looked good.
My first head scratcher came when I had to transfer the common curve to the hips and wall cleats. I know I could have just built it and scribed the curves, but I wanted to understand the geometry. After some research I found this method. http://sbebuilders.blogspot.com/2015/07 ... fters.html This worked beautifully, so now I was left with just cutting the backing angles. I calculated them as I would with straight rafters, but the wall cleat did not come out as anticipated. It appears that the backing angle changes along the span of the cleat. In the end, I just cut it at the calculated angle, then tuned it up with a spokeshave. It is rough, but then again it is rough framing. I would love to do this sometime with an exposed rafter system where it must look good. Does anyone have experience with this?
I am currently building a small hip roof for a bay window. It is a standard 45 degree window with about a 20" projection. I have build one hip roof like this before without trouble, so I decided to give this one a bit of a flare. I played around with different slopes and curves, and ended up settling on a 12/12 pitch, with the radius of curvature on the common rafters set at phi times the rise. I had a hard time finding info on the traditional curves on these roofs, so just went with what looked good.
My first head scratcher came when I had to transfer the common curve to the hips and wall cleats. I know I could have just built it and scribed the curves, but I wanted to understand the geometry. After some research I found this method. http://sbebuilders.blogspot.com/2015/07 ... fters.html This worked beautifully, so now I was left with just cutting the backing angles. I calculated them as I would with straight rafters, but the wall cleat did not come out as anticipated. It appears that the backing angle changes along the span of the cleat. In the end, I just cut it at the calculated angle, then tuned it up with a spokeshave. It is rough, but then again it is rough framing. I would love to do this sometime with an exposed rafter system where it must look good. Does anyone have experience with this?