What's The Best Way To Create These Objects And Match Them To Another Object (References Inside) Primary

I have created some beams that are next to each other.  I have not been able line them up exactly to my standards.

How can I match the shape to the size of the vertical post and have it rest against the post without it clipping? How can I match the shape to the size of the vertical post and have it rest against the post without it clipping?

Secondary

I'm currently following a Stylized Well Tutorial and the homework before part 2 is to create the wooden structure that goes around the well, not including the rope, roof tile, or the ground below. 

It looks like I can get it all done with just using cubes, but I started with the roof supports and I'm having a bit of trouble. 

I will post photos below to supplement my explanation. So I started by stretching my cube (G) and adding a slight bevel. I then inserted a loop cut in the middle and pulled it down to bend the shape. I then lined it up with the vertical posts and grabbed the corners of the face up against the post to match the width. I then rotated the shape downward and moved it back against the post, rotating the face to sit flat with the vertical post. However, I can't seem to line them up perfectly as they look crooked and keep clipping into the vertical posts.

Am I creating these shapes in the most efficient way? How can I match the shape to the size of the vertical post and have it rest against the post without it clipping?

Photos
There probably  isn't a best way, but sometimes it's easier to start this kind of thing in the flat, to keep things simple early on.

Using that approach, with Pivot set to 'Active Element', Vertex Mode, starting with a plane. and the right vertex active. Numpad7 Looking orthographically down Z


ShiftDRZ rotate a copy of the plane out to the desired angle.
K with C and Z cut through with a constraint to the vertical
Face Mode, X delete the unwanted triangle
E extrude all the remaining faces
Edge Mode, all selected, CtrlB bevel the edges