Hi I am looking for some help regarding the angles for 2x2 timber and ply to cover the structure of my aviary roof please. I have attached an image to help give an idea off the shape. The peak of the roof only has to be 4 inches taller than the sides due too keeping the whole construction below 2 meters. The height of each panel is 6 foot 2 inches The back is 4 foot wide The 4 sides are 3 foot The door is 2 foot Hope this enough to work from any questions please ask My shape below This is the roof idea im looking to obtain.
if you can only go 4" higher than the sides, it's never going to look like the pic you hope it will. Getting that design on your structure is easy enough, but I feel it will look rubbish, you would be better of with a pent style roof, higher at the front sloping to the rear.
The higher the better 12" at a minimum. The design is straight forwards though it will involve some neat handy work with a saw on the plywood sheets.
use this website to help you to determine what the angle you need in relation to the pitch - http://www.pole-barn.info/roof-pitch.html or you can use trig to determine the angle you need.
If you want to have a serious lenght and angles and bevel types etc, download this software for Octagon planner http://www.easyrafters.com/octagon.htm or use this website for a hexagon (6 sided) http://www.blocklayer.com/gazebo.aspx to determine your angles etc.
I would lower the height of the side walls. If you compare it to a typical shed or greenhouse they might be 2m high at the apex but the side walls are considerably lower. In your case I'd probably go with 2m (6'8") at the apex and 1.7m (5'8") at the walls. That will give you a 30° slope on the roof which may look better and shed water more effectively.
Get a 4/5 inch round post ( king pin) and stick it the middle of the floor and run it to the height you want the finished roof to be. Take the corners off the walls where you will be running the rafters, so they seat properly. Offer your rafters up from the corners to the king pin and mark your angle, i wouldn't bother with cutting birds mouths on something like this. looking at your drawing the two running from the back should be the same as should the two from the front sides and the two above the door, so you will have 3 pairs…. Screw straight through your rafters in to the king pin and screw up through your walls header to the rafter to secure it at the bottom. Lay a sheet of ply over the rafters, mark from inside and add half the thickness of the rafter to either side of your markings. One bit for the back two sides and two front side sections should be the same and then the front bit Once the ply and tiles/felt are on, cut the king pin out Keep your rafters long so you can adjust the angle incase you don't get it right first cut and cut them plum or shape the tails when they are all fitted, before you cover it……….. Hope that makes sense
If you need to find real angle, try this http://myrooff.com/roof-pitch-calculator/ Most correct calculator